We can disable debug_pagealloc processing even if the code is compiled
with CONFIG_DEBUG_PAGEALLOC. This patch changes the code to query
whether it is enabled or not in runtime.
[akpm@linux-foundation.org: clean up code, per Christian]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Takashi Iwai <tiwai@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As CONFIG_DEBUG_PAGEALLOC can be enabled/disabled via kernel parameters
we can optimize some cases by checking the enablement state.
This is follow-up work for Christian's Optimize CONFIG_DEBUG_PAGEALLOC:
https://lkml.org/lkml/2016/1/27/194
Remaining work is to make sparc to be aware of this but it looks not
easy for me so I skip that in this series.
This patch (of 5):
We can disable debug_pagealloc processing even if the code is complied
with CONFIG_DEBUG_PAGEALLOC. This patch changes the code to query
whether it is enabled or not in runtime.
[akpm@linux-foundation.org: update comment, per David. Adjust comment to use 80 cols]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently /proc/kpageflags returns nothing for "tail" buddy pages, which
is inconvenient when grasping how free pages are distributed. This
patch sets KPF_BUDDY for such pages.
With this patch:
$ grep MemFree /proc/meminfo ; tools/vm/page-types -b buddy
MemFree: 3134992 kB
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000000000400 779272 3044 __________B_______________________________ buddy
0x0000000000000c00 4385 17 __________BM______________________________ buddy,mmap
total 783657 3061
783657 pages is 3134628 kB (roughly consistent with the global counter,)
so it's OK.
[akpm@linux-foundation.org: update comment, per Naoya]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Show how much memory is allocated to kernel stacks.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Show how much memory is used for storing reclaimable and unreclaimable
in-kernel data structures allocated from slab caches.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, tree_{stat,events} helpers can only get one stat index at a
time, so when there are a lot of stats to be reported one has to call it
over and over again (see memory_stat_show). This is neither effective,
nor does it look good. Instead, let's make these helpers take a
snapshot of all available counters.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Slab pages are charged in two steps. First, an appropriate per memcg
cache is selected (see memcg_kmem_get_cache) basing on the current
context, then the new slab page is charged to the memory cgroup which
the selected cache was created for (see memcg_charge_slab ->
__memcg_kmem_charge_memcg). It is OK to bypass kmemcg charge at step 1,
but if step 1 succeeded and we successfully allocated a new slab page,
step 2 must be performed, otherwise we would get a per memcg kmem cache
which contains a slab that does not hold a reference to the memory
cgroup owning the cache. Since per memcg kmem caches are destroyed on
memcg css free, this could result in freeing a cache while there are
still active objects in it.
However, currently we will bypass slab page charge if the memory cgroup
owning the cache is offline (see __memcg_kmem_charge_memcg). This is
very unlikely to occur in practice, because for this to happen a process
must be migrated to a different cgroup and the old cgroup must be
removed while the process is in kmalloc somewhere between steps 1 and 2
(e.g. trying to allocate a new page). Nevertheless, it's still better
to eliminate such a possibility.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When the OOM killer scans tasks and encounters a PF_EXITING one, it
force-selects that task regardless of the score. The problem is that if
that task got stuck waiting for some state the allocation site is
holding, the OOM reaper can not move on to the next best victim.
Frankly, I don't even know why we check for exiting tasks in the OOM
killer. We've tried direct reclaim at least 15 times by the time we
decide the system is OOM, there was plenty of time to exit and free
memory; and a task might exit voluntarily right after we issue a kill.
This is testing pure noise. Remove it.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge first patch-bomb from Andrew Morton:
- some misc things
- ofs2 updates
- about half of MM
- checkpatch updates
- autofs4 update
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (120 commits)
autofs4: fix string.h include in auto_dev-ioctl.h
autofs4: use pr_xxx() macros directly for logging
autofs4: change log print macros to not insert newline
autofs4: make autofs log prints consistent
autofs4: fix some white space errors
autofs4: fix invalid ioctl return in autofs4_root_ioctl_unlocked()
autofs4: fix coding style line length in autofs4_wait()
autofs4: fix coding style problem in autofs4_get_set_timeout()
autofs4: coding style fixes
autofs: show pipe inode in mount options
kallsyms: add support for relative offsets in kallsyms address table
kallsyms: don't overload absolute symbol type for percpu symbols
x86: kallsyms: disable absolute percpu symbols on !SMP
checkpatch: fix another left brace warning
checkpatch: improve UNSPECIFIED_INT test for bare signed/unsigned uses
checkpatch: warn on bare unsigned or signed declarations without int
checkpatch: exclude asm volatile from complex macro check
mm: memcontrol: drop unnecessary lru locking from mem_cgroup_migrate()
mm: migrate: consolidate mem_cgroup_migrate() calls
mm/compaction: speed up pageblock_pfn_to_page() when zone is contiguous
...
Migration accounting in the memory controller used to have to handle
both oldpage and newpage being on the LRU already; fuse's page cache
replacement used to pass a recycled newpage that had been uncharged but
not freed and removed from the LRU, and the memcg migration code used to
uncharge oldpage to "pass on" the existing charge to newpage.
Nowadays, pages are no longer uncharged when truncated from the page
cache, but rather only at free time, so if a LRU page is recycled in
page cache replacement it'll also still be charged. And we bail out of
the charge transfer altogether in that case. Tell commit_charge() that
we know newpage is not on the LRU, to avoid taking the zone->lru_lock
unnecessarily from the migration path.
But also, oldpage is no longer uncharged inside migration. We only use
oldpage for its page->mem_cgroup and page size, so we don't care about
its LRU state anymore either. Remove any mention from the kernel doc.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rather than scattering mem_cgroup_migrate() calls all over the place,
have a single call from a safe place where every migration operation
eventually ends up in - migrate_page_copy().
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a performance drop report due to hugepage allocation and in
there half of cpu time are spent on pageblock_pfn_to_page() in
compaction [1].
In that workload, compaction is triggered to make hugepage but most of
pageblocks are un-available for compaction due to pageblock type and
skip bit so compaction usually fails. Most costly operations in this
case is to find valid pageblock while scanning whole zone range. To
check if pageblock is valid to compact, valid pfn within pageblock is
required and we can obtain it by calling pageblock_pfn_to_page(). This
function checks whether pageblock is in a single zone and return valid
pfn if possible. Problem is that we need to check it every time before
scanning pageblock even if we re-visit it and this turns out to be very
expensive in this workload.
Although we have no way to skip this pageblock check in the system where
hole exists at arbitrary position, we can use cached value for zone
continuity and just do pfn_to_page() in the system where hole doesn't
exist. This optimization considerably speeds up in above workload.
Before vs After
Max: 1096 MB/s vs 1325 MB/s
Min: 635 MB/s 1015 MB/s
Avg: 899 MB/s 1194 MB/s
Avg is improved by roughly 30% [2].
[1]: http://www.spinics.net/lists/linux-mm/msg97378.html
[2]: https://lkml.org/lkml/2015/12/9/23
[akpm@linux-foundation.org: don't forget to restore zone->contiguous on error path, per Vlastimil]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reported-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pageblock_pfn_to_page() is used to check there is valid pfn and all
pages in the pageblock is in a single zone. If there is a hole in the
pageblock, passing arbitrary position to pageblock_pfn_to_page() could
cause to skip whole pageblock scanning, instead of just skipping the
hole page. For deterministic behaviour, it's better to always pass
pageblock aligned range to pageblock_pfn_to_page(). It will also help
further optimization on pageblock_pfn_to_page() in the following patch.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
free_pfn and compact_cached_free_pfn are the pointer that remember
restart position of freepage scanner. When they are reset or invalid,
we set them to zone_end_pfn because freepage scanner works in reverse
direction. But, because zone range is defined as [zone_start_pfn,
zone_end_pfn), zone_end_pfn is invalid to access. Therefore, we should
not store it to free_pfn and compact_cached_free_pfn. Instead, we need
to store zone_end_pfn - 1 to them. There is one more thing we should
consider. Freepage scanner scan reversely by pageblock unit. If
free_pfn and compact_cached_free_pfn are set to middle of pageblock, it
regards that sitiation as that it already scans front part of pageblock
so we lose opportunity to scan there. To fix-up, this patch do
round_down() to guarantee that reset position will be pageblock aligned.
Note that thanks to the current pageblock_pfn_to_page() implementation,
actual access to zone_end_pfn doesn't happen until now. But, following
patch will change pageblock_pfn_to_page() so this patch is needed from
now on.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We define struct memblock_type *type in the memblock_add_region() and
memblock_reserve_region() functions only for passing it to the
memlock_add_range() and memblock_reserve_range() functions. Let's
remove these variables and will pass a type directly.
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After one of bugfixes to freeze_page(), we don't have freezed pages in
rmap, therefore mapcount of all subpages of freezed THP is zero. And we
have assert for that.
Let's drop code which deal with non-zero mapcount of subpages.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_fault() assumes that PAGE_SIZE is the same as PAGE_CACHE_SIZE. Use
linear_page_index() to calculate pgoff in the correct units.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several users that nest lock_page_memcg() inside lock_page()
to prevent page->mem_cgroup from changing. But the page lock prevents
pages from moving between cgroups, so that is unnecessary overhead.
Remove lock_page_memcg() in contexts with locked contexts and fix the
debug code in the page stat functions to be okay with the page lock.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that migration doesn't clear page->mem_cgroup of live pages anymore,
it's safe to make lock_page_memcg() and the memcg stat functions take
pages, and spare the callers from memcg objects.
[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Changing a page's memcg association complicates dealing with the page,
so we want to limit this as much as possible. Page migration e.g. does
not have to do that. Just like page cache replacement, it can forcibly
charge a replacement page, and then uncharge the old page when it gets
freed. Temporarily overcharging the cgroup by a single page is not an
issue in practice, and charging is so cheap nowadays that this is much
preferrable to the headache of messing with live pages.
The only place that still changes the page->mem_cgroup binding of live
pages is when pages move along with a task to another cgroup. But that
path isolates the page from the LRU, takes the page lock, and the move
lock (lock_page_memcg()). That means page->mem_cgroup is always stable
in callers that have the page isolated from the LRU or locked. Lighter
unlocked paths, like writeback accounting, can use lock_page_memcg().
[akpm@linux-foundation.org: fix build]
[vdavydov@virtuozzo.com: fix lockdep splat]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cache thrash detection (see a528910e12 "mm: thrash detection-based
file cache sizing" for details) currently only works on the system
level, not inside cgroups. Worse, as the refaults are compared to the
global number of active cache, cgroups might wrongfully get all their
refaults activated when their pages are hotter than those of others.
Move the refault machinery from the zone to the lruvec, and then tag
eviction entries with the memcg ID. This makes the thrash detection
work correctly inside cgroups.
[sergey.senozhatsky@gmail.com: do not return from workingset_activation() with locked rcu and page]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For per-cgroup thrash detection, we need to store the memcg ID inside
the radix tree cookie as well. However, on 32 bit that doesn't leave
enough bits for the eviction timestamp to cover the necessary range of
recently evicted pages. The radix tree entry would look like this:
[ RADIX_TREE_EXCEPTIONAL(2) | ZONEID(2) | MEMCGID(16) | EVICTION(12) ]
12 bits means 4096 pages, means 16M worth of recently evicted pages.
But refaults are actionable up to distances covering half of memory. To
not miss refaults, we have to stretch out the range at the cost of how
precisely we can tell when a page was evicted. This way we can shave
off lower bits from the eviction timestamp until the necessary range is
covered. E.g. grouping evictions into 1M buckets (256 pages) will
stretch the longest representable refault distance to 4G.
This patch implements eviction buckets that are automatically sized
according to the available bits and the necessary refault range, in
preparation for per-cgroup thrash detection.
The maximum actionable distance is currently half of memory, but to
support memory hotplug of up to 200% of boot-time memory, we size the
buckets to cover double the distance. Beyond that, thrashing won't be
detectable anymore.
During boot, the kernel will print out the exact parameters, like so:
[ 0.113929] workingset: timestamp_bits=12 max_order=18 bucket_order=6
In this example, there are 12 radix entry bits available for the
eviction timestamp, to cover a maximum distance of 2^18 pages (this is a
1G machine). Consequently, evictions must be grouped into buckets of
2^6 pages, or 256K.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Per-cgroup thrash detection will need to derive a live memcg from the
eviction cookie, and doing that inside unpack_shadow() will get nasty
with the reference handling spread over two functions.
In preparation, make unpack_shadow() clearly about extracting static
data, and let workingset_refault() do all the higher-level handling.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a compile-time constant, no need to calculate it on refault.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These patches tag the page cache radix tree eviction entries with the
memcg an evicted page belonged to, thus making per-cgroup LRU reclaim
work properly and be as adaptive to new cache workingsets as global
reclaim already is.
This should have been part of the original thrash detection patch
series, but was deferred due to the complexity of those patches.
This patch (of 5):
So far the only sites that needed to exclude charge migration to
stabilize page->mem_cgroup have been per-cgroup page statistics, hence
the name mem_cgroup_begin_page_stat(). But per-cgroup thrash detection
will add another site that needs to ensure page->mem_cgroup lifetime.
Rename these locking functions to the more generic lock_page_memcg() and
unlock_page_memcg(). Since charge migration is a cgroup1 feature only,
we might be able to delete it at some point, and these now easy to
identify locking sites along with it.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zone_reclaimable_pages() is used in should_reclaim_retry() which uses it
to calculate the target for the watermark check. This means that
precise numbers are important for the correct decision.
zone_reclaimable_pages uses zone_page_state which can contain stale data
with per-cpu diffs not synced yet (the last vmstat_update might have run
1s in the past).
Use zone_page_state_snapshot() in zone_reclaimable_pages() instead.
None of the current callers is in a hot path where getting the precise
value (which involves per-cpu iteration) would cause an unreasonable
overhead.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Suggested-by: David Rientjes <rientjes@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some new MADV_* advices are not documented in sys_madvise() comment. So
let's update it.
[akpm@linux-foundation.org: modifications suggested by Michal]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, on shrinker registration we clear SHRINKER_NUMA_AWARE if
there's the only NUMA node present. The comment states that this will
allow us to save some small loop time later. It used to be true when
this code was added (see commit 1d3d4437ea ("vmscan: per-node
deferred work")), but since commit 6b4f7799c6 ("mm: vmscan: invoke
slab shrinkers from shrink_zone()") it doesn't make any difference.
Anyway, running on non-NUMA machine shouldn't make a shrinker NUMA
unaware, so zap this hunk.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, all newly added memory blocks remain in 'offline' state
unless someone onlines them, some linux distributions carry special udev
rules like:
SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"
to make this happen automatically. This is not a great solution for
virtual machines where memory hotplug is being used to address high
memory pressure situations as such onlining is slow and a userspace
process doing this (udev) has a chance of being killed by the OOM killer
as it will probably require to allocate some memory.
Introduce default policy for the newly added memory blocks in
/sys/devices/system/memory/auto_online_blocks file with two possible
values: "offline" which preserves the current behavior and "online"
which causes all newly added memory blocks to go online as soon as
they're added. The default is "offline".
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Arm and arm64 used to trigger this BUG_ON() - this has now been fixed.
But a WARN_ON() here is sufficient to catch future buggy callers.
Signed-off-by: Mika Penttilä <mika.penttila@nextfour.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
VM_HUGETLB and VM_MIXEDMAP vma needs to be excluded to avoid compound
pages being marked for migration and unexpected COWs when handling
hugetlb fault.
Thanks to Naoya Horiguchi for reminding me on these checks.
Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Signed-off-by: Gavin Guo <gavin.guo@canonical.com>
Suggested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: SeongJae Park <sj38.park@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the useless #undef, since the corresponding #define has already
been removed.
Signed-off-by: Wang Xiaoqiang <wangxq10@lzu.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the return value of memory_failure() is not passed to
userspace when madvise(MADV_HWPOISON) is used. This is inconvenient for
test programs that want to know the result of error handling. So let's
return it to the caller as we already do in the MADV_SOFT_OFFLINE case.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can now print gfp_flags more human-readable. Make use of this in
slab_out_of_memory() for SLUB and SLAB. Also convert the SLAB variant
it to pr_warn() along the way.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
By default, page poisoning uses a poison value (0xaa) on free. If this
is changed to 0, the page is not only sanitized but zeroing on alloc
with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
corruption from the poisoning is harder to detect. This feature also
cannot be used with hibernation since pages are not guaranteed to be
zeroed after hibernation.
Credit to Grsecurity/PaX team for inspiring this work
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Page poisoning is currently set up as a feature if architectures don't
have architecture debug page_alloc to allow unmapping of pages. It has
uses apart from that though. Clearing of the pages on free provides an
increase in security as it helps to limit the risk of information leaks.
Allow page poisoning to be enabled as a separate option independent of
kernel_map pages since the two features do separate work. Because of
how hiberanation is implemented, the checks on alloc cannot occur if
hibernation is enabled. The runtime alloc checks can also be enabled
with an option when !HIBERNATION.
Credit to Grsecurity/PaX team for inspiring this work
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since bad_page() is the only user of the badflags parameter of
dump_page_badflags(), we can move the code to bad_page() and simplify a
bit.
The dump_page_badflags() function is renamed to __dump_page() and can
still be called separately from dump_page() for temporary debug prints
where page_owner info is not desired.
The only user-visible change is that page->mem_cgroup is printed before
the bad flags.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page_owner mechanism is useful for dealing with memory leaks. By
reading /sys/kernel/debug/page_owner one can determine the stack traces
leading to allocations of all pages, and find e.g. a buggy driver.
This information might be also potentially useful for debugging, such as
the VM_BUG_ON_PAGE() calls to dump_page(). So let's print the stored
info from dump_page().
Example output:
page:ffffea000292f1c0 count:1 mapcount:0 mapping:ffff8800b2f6cc18 index:0x91d
flags: 0x1fffff8001002c(referenced|uptodate|lru|mappedtodisk)
page dumped because: VM_BUG_ON_PAGE(1)
page->mem_cgroup:ffff8801392c5000
page allocated via order 0, migratetype Movable, gfp_mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY)
[<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230
[<ffffffff811b40c8>] alloc_pages_current+0x88/0x120
[<ffffffff8115e386>] __page_cache_alloc+0xe6/0x120
[<ffffffff8116ba6c>] __do_page_cache_readahead+0xdc/0x240
[<ffffffff8116bd05>] ondemand_readahead+0x135/0x260
[<ffffffff8116be9c>] page_cache_async_readahead+0x6c/0x70
[<ffffffff811604c2>] generic_file_read_iter+0x3f2/0x760
[<ffffffff811e0dc7>] __vfs_read+0xa7/0xd0
page has been migrated, last migrate reason: compaction
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During migration, page_owner info is now copied with the rest of the
page, so the stacktrace leading to free page allocation during migration
is overwritten. For debugging purposes, it might be however useful to
know that the page has been migrated since its initial allocation. This
might happen many times during the lifetime for different reasons and
fully tracking this, especially with stacktraces would incur extra
memory costs. As a compromise, store and print the migrate_reason of
the last migration that occurred to the page. This is enough to
distinguish compaction, numa balancing etc.
Example page_owner entry after the patch:
Page allocated via order 0, mask 0x24200ca(GFP_HIGHUSER_MOVABLE)
PFN 628753 type Movable Block 1228 type Movable Flags 0x1fffff80040030(dirty|lru|swapbacked)
[<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230
[<ffffffff811b6325>] alloc_pages_vma+0xb5/0x250
[<ffffffff81177491>] shmem_alloc_page+0x61/0x90
[<ffffffff8117a438>] shmem_getpage_gfp+0x678/0x960
[<ffffffff8117c2b9>] shmem_fallocate+0x329/0x440
[<ffffffff811de600>] vfs_fallocate+0x140/0x230
[<ffffffff811df434>] SyS_fallocate+0x44/0x70
[<ffffffff8158cc2e>] entry_SYSCALL_64_fastpath+0x12/0x71
Page has been migrated, last migrate reason: compaction
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page_owner mechanism stores gfp_flags of an allocation and stack
trace that lead to it. During page migration, the original information
is practically replaced by the allocation of free page as the migration
target. Arguably this is less useful and might lead to all the
page_owner info for migratable pages gradually converge towards
compaction or numa balancing migrations. It has also lead to
inaccuracies such as one fixed by commit e2cfc91120 ("mm/page_owner:
set correct gfp_mask on page_owner").
This patch thus introduces copying the page_owner info during migration.
However, since the fact that the page has been migrated from its
original place might be useful for debugging, the next patch will
introduce a way to track that information as well.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_PAGE_OWNER attempts to impose negligible runtime overhead when
enabled during compilation, but not actually enabled during runtime by
boot param page_owner=on. This overhead can be further reduced using
the static key mechanism, which this patch does.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The information in /sys/kernel/debug/page_owner includes the migratetype
of the pageblock the page belongs to. This is also checked against the
page's migratetype (as declared by gfp_flags during its allocation), and
the page is reported as Fallback if its migratetype differs from the
pageblock's one. t This is somewhat misleading because in fact fallback
allocation is not the only reason why these two can differ. It also
doesn't direcly provide the page's migratetype, although it's possible
to derive that from the gfp_flags.
It's arguably better to print both page and pageblock's migratetype and
leave the interpretation to the consumer than to suggest fallback
allocation as the only possible reason. While at it, we can print the
migratetypes as string the same way as /proc/pagetypeinfo does, as some
of the numeric values depend on kernel configuration. For that, this
patch moves the migratetype_names array from #ifdef CONFIG_PROC_FS part
of mm/vmstat.c to mm/page_alloc.c and exports it.
With the new format strings for flags, we can now also provide symbolic
page and gfp flags in the /sys/kernel/debug/page_owner file. This
replaces the positional printing of page flags as single letters, which
might have looked nicer, but was limited to a subset of flags, and
required the user to remember the letters.
Example page_owner entry after the patch:
Page allocated via order 0, mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY)
PFN 520 type Movable Block 1 type Movable Flags 0xfffff8001006c(referenced|uptodate|lru|active|mappedtodisk)
[<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230
[<ffffffff811b4058>] alloc_pages_current+0x88/0x120
[<ffffffff8115e386>] __page_cache_alloc+0xe6/0x120
[<ffffffff8116ba6c>] __do_page_cache_readahead+0xdc/0x240
[<ffffffff8116bd05>] ondemand_readahead+0x135/0x260
[<ffffffff8116bfb1>] page_cache_sync_readahead+0x31/0x50
[<ffffffff81160523>] generic_file_read_iter+0x453/0x760
[<ffffffff811e0d57>] __vfs_read+0xa7/0xd0
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It would be useful to translate gfp_flags into string representation
when printing in case of an OOM, especially as the flags have been
undergoing some changes recently and the script ./scripts/gfp-translate
needs a matching source version to be accurate.
Example output:
a.out invoked oom-killer: gfp_mask=0x24280ca(GFP_HIGHUSER_MOVABLE|GFP_ZERO), order=0, om_score_adj=0
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It would be useful to translate gfp_flags into string representation
when printing in case of an allocation failure, especially as the flags
have been undergoing some changes recently and the script
./scripts/gfp-translate needs a matching source version to be accurate.
Example output:
stapio: page allocation failure: order:9, mode:0x2080020(GFP_ATOMIC)
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the new printk format strings for flags, we can get rid of
dump_flags() in mm/debug.c.
This also fixes dump_vma() which used dump_flags() for printing vma
flags. However dump_flags() did a page-flags specific filtering of bits
higher than NR_PAGEFLAGS in order to remove the zone id part. For
dump_vma() this resulted in removing several VM_* flags from the
symbolic translation.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In mm we use several kinds of flags bitfields that are sometimes printed
for debugging purposes, or exported to userspace via sysfs. To make
them easier to interpret independently on kernel version and config, we
want to dump also the symbolic flag names. So far this has been done
with repeated calls to pr_cont(), which is unreliable on SMP, and not
usable for e.g. sysfs export.
To get a more reliable and universal solution, this patch extends
printk() format string for pointers to handle the page flags (%pGp),
gfp_flags (%pGg) and vma flags (%pGv). Existing users of
dump_flag_names() are converted and simplified.
It would be possible to pass flags by value instead of pointer, but the
%p format string for pointers already has extensions for various kernel
structures, so it's a good fit, and the extra indirection in a
non-critical path is negligible.
[linux@rasmusvillemoes.dk: lots of good implementation suggestions]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In tracepoints, it's possible to print gfp flags in a human-friendly
format through a macro show_gfp_flags(), which defines a translation
array and passes is to __print_flags(). Since the following patch will
introduce support for gfp flags printing in printk(), it would be nice
to reuse the array. This is not straightforward, since __print_flags()
can't simply reference an array defined in a .c file such as mm/debug.c
- it has to be a macro to allow the macro magic to communicate the
format to userspace tools such as trace-cmd.
The solution is to create a macro __def_gfpflag_names which is used both
in show_gfp_flags(), and to define the gfpflag_names[] array in
mm/debug.c.
On the other hand, mm/debug.c also defines translation tables for page
flags and vma flags, and desire was expressed (but not implemented in
this series) to use these also from tracepoints. Thus, this patch also
renames the events/gfpflags.h file to events/mmflags.h and moves the
table definitions there, using the same macro approach as for gfpflags.
This allows translating all three kinds of mm-specific flags both in
tracepoints and printk.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the generic read paths the kernel looks up a page in the page cache
and if it's up to date, it is used. If not, the page lock is acquired
to wait for IO to complete and then check the page. If multiple
processes are waiting on IO, they all serialise against the lock and
duplicate the checks. This is unnecessary.
The page lock in itself does not give any guarantees to the callers
about the page state as it can be immediately truncated or reclaimed
after the page is unlocked. It's sufficient to wait_on_page_locked and
then continue if the page is up to date on wakeup.
It is possible that a truncated but up-to-date page is returned but the
reference taken during read prevents it disappearing underneath the
caller and the data is still valid if PageUptodate.
The overall impact is small as even if processes serialise on the lock,
the lock section is tiny once the IO is complete. Profiles indicated
that unlock_page and friends are generally a tiny portion of a
read-intensive workload. An artificial test was created that had
instances of dd access a cache-cold file on an ext4 filesystem and
measure how long the read took.
paralleldd
4.4.0 4.4.0
vanilla avoidlock
Amean Elapsd-1 5.28 ( 0.00%) 5.15 ( 2.50%)
Amean Elapsd-4 5.29 ( 0.00%) 5.17 ( 2.12%)
Amean Elapsd-7 5.28 ( 0.00%) 5.18 ( 1.78%)
Amean Elapsd-12 5.20 ( 0.00%) 5.33 ( -2.50%)
Amean Elapsd-21 5.14 ( 0.00%) 5.21 ( -1.41%)
Amean Elapsd-30 5.30 ( 0.00%) 5.12 ( 3.38%)
Amean Elapsd-48 5.78 ( 0.00%) 5.42 ( 6.21%)
Amean Elapsd-79 6.78 ( 0.00%) 6.62 ( 2.46%)
Amean Elapsd-110 9.09 ( 0.00%) 8.99 ( 1.15%)
Amean Elapsd-128 10.60 ( 0.00%) 10.43 ( 1.66%)
The impact is small but intuitively, it makes sense to avoid unnecessary
calls to lock_page.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_read_cache_page and __read_cache_page duplicate page filler code when
filling the page for the first time. This patch simply removes the
duplicate logic.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 031bc5743f ("mm/debug-pagealloc: make debug-pagealloc
boottime configurable") CONFIG_DEBUG_PAGEALLOC is by default not adding
any page debugging.
This resulted in several unnoticed bugs, e.g.
https://lkml.kernel.org/g/<569F5E29.3090107@de.ibm.com>
or
https://lkml.kernel.org/g/<56A20F30.4050705@de.ibm.com>
as this behaviour change was not even documented in Kconfig.
Let's provide a new Kconfig symbol that allows to change the default
back to enabled, e.g. for debug kernels. This also makes the change
obvious to kernel packagers.
Let's also change the Kconfig description for CONFIG_DEBUG_PAGEALLOC, to
indicate that there are two stages of overhead.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Calculation of dirty_ratelimit sometimes is not correct. E.g. initial
values of dirty_ratelimit == INIT_BW and step == 0, lead to the
following result:
UBSAN: Undefined behaviour in ../mm/page-writeback.c:1286:7
shift exponent 25600 is too large for 64-bit type 'long unsigned int'
The fix is straightforward - make step 0 if the shift exponent is too
big.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function is getting full of weird tricks to avoid word-wrapping.
Use a goto to eliminate a tab stop then use the new space
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Xeon E7 v3 based systems supports Address Range Mirroring and UEFI BIOS
complied with UEFI spec 2.5 can notify which ranges are mirrored
(reliable) via EFI memory map. Now Linux kernel utilize its information
and allocates boot time memory from reliable region.
My requirement is:
- allocate kernel memory from mirrored region
- allocate user memory from non-mirrored region
In order to meet my requirement, ZONE_MOVABLE is useful. By arranging
non-mirrored range into ZONE_MOVABLE, mirrored memory is used for kernel
allocations.
My idea is to extend existing "kernelcore" option and introduces
kernelcore=mirror option. By specifying "mirror" instead of specifying
the amount of memory, non-mirrored region will be arranged into
ZONE_MOVABLE.
Earlier discussions are at:
https://lkml.org/lkml/2015/10/9/24https://lkml.org/lkml/2015/10/15/9https://lkml.org/lkml/2015/11/27/18https://lkml.org/lkml/2015/12/8/836
For example, suppose 2-nodes system with the following memory range:
node 0 [mem 0x0000000000001000-0x000000109fffffff]
node 1 [mem 0x00000010a0000000-0x000000209fffffff]
and the following ranges are marked as reliable (mirrored):
[0x0000000000000000-0x0000000100000000]
[0x0000000100000000-0x0000000180000000]
[0x0000000800000000-0x0000000880000000]
[0x00000010a0000000-0x0000001120000000]
[0x00000017a0000000-0x0000001820000000]
If you specify kernelcore=mirror, ZONE_NORMAL and ZONE_MOVABLE are
arranged like bellow:
- node 0:
ZONE_NORMAL : [0x0000000100000000-0x00000010a0000000]
ZONE_MOVABLE: [0x0000000180000000-0x00000010a0000000]
- node 1:
ZONE_NORMAL : [0x00000010a0000000-0x00000020a0000000]
ZONE_MOVABLE: [0x0000001120000000-0x00000020a0000000]
In overlapped range, pages to be ZONE_MOVABLE in ZONE_NORMAL are treated
as absent pages, and vice versa.
This patch (of 2):
Currently each zone's zone_start_pfn is calculated at
free_area_init_core(). However zone's range is fixed at the time when
invoking zone_spanned_pages_in_node().
This patch changes how each zone->zone_start_pfn is calculated in
zone_spanned_pages_in_node().
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLUB already has a redzone debugging feature. But it is only positioned
at the end of object (aka right redzone) so it cannot catch left oob.
Although current object's right redzone acts as left redzone of next
object, first object in a slab cannot take advantage of this effect.
This patch explicitly adds a left red zone to each object to detect left
oob more precisely.
Background:
Someone complained to me that left OOB doesn't catch even if KASAN is
enabled which does page allocation debugging. That page is out of our
control so it would be allocated when left OOB happens and, in this
case, we can't find OOB. Moreover, SLUB debugging feature can be
enabled without page allocator debugging and, in this case, we will miss
that OOB.
Before trying to implement, I expected that changes would be too
complex, but, it doesn't look that complex to me now. Almost changes
are applied to debug specific functions so I feel okay.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When debug options are enabled, cmpxchg on the page is disabled. This
is because the page must be locked to ensure there are no false
positives when performing consistency checks. Some debug options such
as poisoning and red zoning only act on the object itself. There is no
need to protect other CPUs from modification on only the object. Allow
cmpxchg to happen with poisoning and red zoning are set on a slab.
Credit to Mathias Krause for the original work which inspired this
series
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLAB_DEBUG_FREE allows expensive consistency checks at free to be turned
on or off. Expand its use to be able to turn off all consistency
checks. This gives a nice speed up if you only want features such as
poisoning or tracing.
Credit to Mathias Krause for the original work which inspired this
series
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 19c7ff9ecd ("slub: Take node lock during object free
checks") check_object has been incorrectly returning success as it
follows the out label which just returns the node.
Thanks to refactoring, the out and fail paths are now basically the
same. Combine the two into one and just use a single label.
Credit to Mathias Krause for the original work which inspired this
series
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This series takes the suggestion of Christoph Lameter and only focuses
on optimizing the slow path where the debug processing runs. The two
main optimizations in this series are letting the consistency checks be
skipped and relaxing the cmpxchg restrictions when we are not doing
consistency checks. With hackbench -g 20 -l 1000 averaged over 100
runs:
Before slub_debug=P
mean 15.607
variance .086
stdev .294
After slub_debug=P
mean 10.836
variance .155
stdev .394
This still isn't as fast as what is in grsecurity unfortunately so there's
still work to be done. Profiling ___slab_alloc shows that 25-50% of time
is spent in deactivate_slab. I haven't looked too closely to see if this
is something that can be optimized. My plan for now is to focus on
getting all of this merged (if appropriate) before digging in to another
task.
This patch (of 4):
Currently, free_debug_processing has a comment "Keep node_lock to preserve
integrity until the object is actually freed". In actuallity, the lock is
dropped immediately in __slab_free. Rather than wait until __slab_free
and potentially throw off the unlikely marking, just drop the lock in
__slab_free. This also lets free_debug_processing take its own copy of
the spinlock flags rather than trying to share the ones from __slab_free.
Since there is no use for the node afterwards, change the return type of
free_debug_processing to return an int like alloc_debug_processing.
Credit to Mathias Krause for the original work which inspired this series
[akpm@linux-foundation.org: fix build]
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Current implementation of pfmemalloc handling in SLAB has some problems.
1) pfmemalloc_active is set to true when there is just one or more
pfmemalloc slabs in the system, but it is cleared when there is no
pfmemalloc slab in one arbitrary kmem_cache. So, pfmemalloc_active
could be wrongly cleared.
2) Search to partial and free list doesn't happen when non-pfmemalloc
object are not found in cpu cache. Instead, allocating new slab
happens and it is not optimal.
3) Even after sk_memalloc_socks() is disabled, cpu cache would keep
pfmemalloc objects tagged with SLAB_OBJ_PFMEMALLOC. It isn't cleared
if sk_memalloc_socks() is disabled so it could cause problem.
4) If cpu cache is filled with pfmemalloc objects, it would cause slow
down non-pfmemalloc allocation.
To me, current pointer tagging approach looks complex and fragile so this
patch re-implement whole thing instead of fixing problems one by one.
Design principle for new implementation is that
1) Don't disrupt non-pfmemalloc allocation in fast path even if
sk_memalloc_socks() is enabled. It's more likely case than pfmemalloc
allocation.
2) Ensure that pfmemalloc slab is used only for pfmemalloc allocation.
3) Don't consider performance of pfmemalloc allocation in memory
deficiency state.
As a result, all pfmemalloc alloc/free in memory tight state will be
handled in slow-path. If there is non-pfmemalloc free object, it will be
returned first even for pfmemalloc user in fast-path so that performance
of pfmemalloc user isn't affected in normal case and pfmemalloc objects
will be kept as long as possible.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Returing values by reference is bad practice. Instead, just use
function return value.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Suggested-by: Christoph Lameter <cl@linux.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLAB needs an array to manage freed objects in a slab. It is only used
if some objects are freed so we can use free object itself as this
array. This requires additional branch in somewhat critical lock path
to check if it is first freed object or not but that's all we need.
Benefits is that we can save extra memory usage and reduce some
computational overhead by allocating a management array when new slab is
created.
Code change is rather complex than what we can expect from the idea, in
order to handle debugging feature efficiently. If you want to see core
idea only, please remove '#if DEBUG' block in the patch.
Although this idea can apply to all caches whose size is larger than
management array size, it isn't applied to caches which have a
constructor. If such cache's object is used for management array,
constructor should be called for it before that object is returned to
user. I guess that overhead overwhelm benefit in that case so this idea
doesn't applied to them at least now.
For summary, from now on, slab management type is determined by
following logic.
1) if management array size is smaller than object size and no ctor, it
becomes OBJFREELIST_SLAB.
2) if management array size is smaller than leftover, it becomes
NORMAL_SLAB which uses leftover as a array.
3) if OFF_SLAB help to save memory than way 4), it becomes OFF_SLAB.
It allocate a management array from the other cache so memory waste
happens.
4) others become NORMAL_SLAB. It uses dedicated internal memory in a
slab as a management array so it causes memory waste.
In my system, without enabling CONFIG_DEBUG_SLAB, Almost caches become
OBJFREELIST_SLAB and NORMAL_SLAB (using leftover) which doesn't waste
memory. Following is the result of number of caches with specific slab
management type.
TOTAL = OBJFREELIST + NORMAL(leftover) + NORMAL + OFF
/Before/
126 = 0 + 60 + 25 + 41
/After/
126 = 97 + 12 + 15 + 2
Result shows that number of caches that doesn't waste memory increase
from 60 to 109.
I did some benchmarking and it looks that benefit are more than loss.
Kmalloc: Repeatedly allocate then free test
/Before/
[ 0.286809] 1. Kmalloc: Repeatedly allocate then free test
[ 1.143674] 100000 times kmalloc(32) -> 116 cycles kfree -> 78 cycles
[ 1.441726] 100000 times kmalloc(64) -> 121 cycles kfree -> 80 cycles
[ 1.815734] 100000 times kmalloc(128) -> 168 cycles kfree -> 85 cycles
[ 2.380709] 100000 times kmalloc(256) -> 287 cycles kfree -> 95 cycles
[ 3.101153] 100000 times kmalloc(512) -> 370 cycles kfree -> 117 cycles
[ 3.942432] 100000 times kmalloc(1024) -> 413 cycles kfree -> 156 cycles
[ 5.227396] 100000 times kmalloc(2048) -> 622 cycles kfree -> 248 cycles
[ 7.519793] 100000 times kmalloc(4096) -> 1102 cycles kfree -> 452 cycles
/After/
[ 1.205313] 100000 times kmalloc(32) -> 117 cycles kfree -> 78 cycles
[ 1.510526] 100000 times kmalloc(64) -> 124 cycles kfree -> 81 cycles
[ 1.827382] 100000 times kmalloc(128) -> 130 cycles kfree -> 84 cycles
[ 2.226073] 100000 times kmalloc(256) -> 177 cycles kfree -> 92 cycles
[ 2.814747] 100000 times kmalloc(512) -> 286 cycles kfree -> 112 cycles
[ 3.532952] 100000 times kmalloc(1024) -> 344 cycles kfree -> 141 cycles
[ 4.608777] 100000 times kmalloc(2048) -> 519 cycles kfree -> 210 cycles
[ 6.350105] 100000 times kmalloc(4096) -> 789 cycles kfree -> 391 cycles
In fact, I tested another idea implementing OBJFREELIST_SLAB with
extendable linked array through another freed object. It can remove
memory waste completely but it causes more computational overhead in
critical lock path and it seems that overhead outweigh benefit. So, this
patch doesn't include it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cache_init_objs() will be changed in following patch and current form
doesn't fit well for that change. So, before doing it, this patch
separates debugging initialization. This would cause two loop iteration
when debugging is enabled, but, this overhead seems too light than debug
feature itself so effect may not be visible. This patch will greatly
simplify changes in cache_init_objs() in following patch.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Slab list should be fixed up after object is detached from the slab and
this happens at two places. They do exactly same thing. They will be
changed in the following patch, so, to reduce code duplication, this
patch factor out them and make it common function.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To become an off slab, there are some constraints to avoid bootstrapping
problem and recursive call. This can be avoided differently by simply
checking that corresponding kmalloc cache is ready and it's not a off
slab. It would be more robust because static size checking can be
affected by cache size change or architecture type but dynamic checking
isn't.
One check 'freelist_cache->size > cachep->size / 2' is added to check
benefit of choosing off slab, because, now, there is no size constraint
which ensures enough advantage when selecting off slab.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can fail to setup off slab in some conditions. Even in this case,
debug pagealloc increases cache size to PAGE_SIZE in advance and it is
waste because debug pagealloc cannot work for it when it isn't the off
slab. To improve this situation, this patch checks first that this
cache with increased size is suitable for off slab. It actually
increases cache size when it is suitable for off-slab, so possible waste
is removed.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Current cache type determination code is open-code and looks not
understandable. Following patch will introduce one more cache type and
it would make code more complex. So, before it happens, this patch
abstracts these codes.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Finding suitable OFF_SLAB candidate is more related to aligned cache
size rather than original size. Same reasoning can be applied to the
debug pagealloc candidate. So, this patch moves up alignment fixup to
proper position. From that point, size is aligned so we can remove some
alignment fixups.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the freelist is at the front of slab page. This requires
extra space to meet object alignment requirement. If we put the
freelist at the end of a slab page, objects could start at page boundary
and will be at correct alignment. This is possible because freelist has
no alignment constraint itself.
This gives us two benefits: It removes extra memory space for the
freelist alignment and remove complex calculation at cache
initialization step. I can't think notable drawback here.
I mentioned that this would reduce extra memory space, but, this benefit
is rather theoretical because it can be applied to very few cases.
Following is the example cache type that can get benefit from this
change.
size align num before after
32 8 124 4100 4092
64 8 63 4103 4095
88 8 46 4102 4094
272 8 15 4103 4095
408 8 10 4098 4090
32 16 124 4108 4092
64 16 63 4111 4095
32 32 124 4124 4092
64 32 63 4127 4095
96 32 42 4106 4074
before means whole size for objects and aligned freelist before applying
patch and after shows the result of this patch.
Since before is more than 4096, number of object should decrease and
memory waste happens.
Anyway, this patch removes complex calculation so looks beneficial to
me.
[akpm@linux-foundation.org: fix kerneldoc]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now, we don't use object status buffer in any setup. Remove it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
DEBUG_SLAB_LEAK is a debug option. It's current implementation requires
status buffer so we need more memory to use it. And, it cause
kmem_cache initialization step more complex.
To remove this extra memory usage and to simplify initialization step,
this patch implement this feature with another way.
When user requests to get slab object owner information, it marks that
getting information is started. And then, all free objects in caches
are flushed to corresponding slab page. Now, we can distinguish all
freed object so we can know all allocated objects, too. After
collecting slab object owner information on allocated objects, mark is
checked that there is no free during the processing. If true, we can be
sure that our information is correct so information is returned to user.
Although this way is rather complex, it has two important benefits
mentioned above. So, I think it is worth changing.
There is one drawback that it takes more time to get slab object owner
information but it is just a debug option so it doesn't matter at all.
To help review, this patch implements new way only. Following patch
will remove useless code.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, open code for checking DEBUG_PAGEALLOC cache is spread to
some sites. It makes code unreadable and hard to change.
This patch cleans up this code. The following patch will change the
criteria for DEBUG_PAGEALLOC cache so this clean-up will help it, too.
[akpm@linux-foundation.org: fix build with CONFIG_DEBUG_PAGEALLOC=n]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
debug_pagealloc debugging is related to SLAB_POISON flag rather than
FORCED_DEBUG option, although FORCED_DEBUG option will enable
SLAB_POISON. Fix it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some of "#if DEBUG" are for reporting slab implementation bug rather
than user usecase bug. It's not really needed because slab is stable
for a quite long time and it makes code too dirty. This patch remove
it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is obsolete so remove it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset implements a new freed object management way, that is,
OBJFREELIST_SLAB. Purpose of it is to reduce memory overhead in SLAB.
SLAB needs a array to manage freed objects in a slab. If there is
leftover after objects are packed into a slab, we can use it as a
management array, and, in this case, there is no memory waste. But, in
the other cases, we need to allocate extra memory for a management array
or utilize dedicated internal memory in a slab for it. Both cases
causes memory waste so it's not good.
With this patchset, freed object itself can be used for a management
array. So, memory waste could be reduced. Detailed idea and numbers
are described in last patch's commit description. Please refer it.
In fact, I tested another idea implementing OBJFREELIST_SLAB with
extendable linked array through another freed object. It can remove
memory waste completely but it causes more computational overhead in
critical lock path and it seems that overhead outweigh benefit. So,
this patchset doesn't include it. I will attach prototype just for a
reference.
This patch (of 16):
We use freelist_idx_t type for free object management whose size would be
smaller than size of unsigned int. Fix it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix up trivial spelling errors, noticed while reading the code.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the call to cache_alloc_debugcheck_after() outside the IRQ disabled
section in kmem_cache_alloc_bulk().
When CONFIG_DEBUG_SLAB is disabled the compiler should remove this code.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch implements the alloc side of bulk API for the SLAB allocator.
Further optimization are still possible by changing the call to
__do_cache_alloc() into something that can return multiple objects.
This optimization is left for later, given end results already show in
the area of 80% speedup.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewers notice that the order in slab_post_alloc_hook() of
kmemcheck_slab_alloc() and kmemleak_alloc_recursive() gets swapped
compared to slab.c / SLAB allocator.
Also notice memset now occurs before calling kmemcheck_slab_alloc() and
kmemleak_alloc_recursive().
I assume this reordering of kmemcheck, kmemleak and memset is okay
because this is the order they are used by the SLUB allocator.
This patch completes the sharing of alloc_hook's between SLUB and SLAB.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the SLAB allocator kmemcheck_slab_alloc() is guarded against being
called in case the object is NULL. In SLUB allocator this NULL pointer
invocation can happen, which seems like an oversight.
Move the NULL pointer check into kmemcheck code (kmemcheck_slab_alloc)
so the check gets moved out of the fastpath, when not compiled with
CONFIG_KMEMCHECK.
This is a step towards sharing post_alloc_hook between SLUB and SLAB,
because slab_post_alloc_hook() does not perform this check before
calling kmemcheck_slab_alloc().
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Deduplicate code in SLAB allocator functions slab_alloc() and
slab_alloc_node() by using the slab_pre_alloc_hook() call, which is now
shared between SLUB and SLAB.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the SLAB specific function slab_should_failslab(), by moving the
check against fault-injection for the bootstrap slab, into the shared
function should_failslab() (used by both SLAB and SLUB).
This is a step towards sharing alloc_hook's between SLUB and SLAB.
This bootstrap slab "kmem_cache" is used for allocating struct
kmem_cache objects to the allocator itself.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
First step towards sharing alloc_hook's between SLUB and SLAB
allocators. Move the SLUB allocators *_alloc_hook to the common
mm/slab.h for internal slab definitions.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This change is primarily an attempt to make it easier to realize the
optimizations the compiler performs in-case CONFIG_MEMCG_KMEM is not
enabled.
Performance wise, even when CONFIG_MEMCG_KMEM is compiled in, the
overhead is zero. This is because, as long as no process have enabled
kmem cgroups accounting, the assignment is replaced by asm-NOP
operations. This is possible because memcg_kmem_enabled() uses a
static_key_false() construct.
It also helps readability as it avoid accessing the p[] array like:
p[size - 1] which "expose" that the array is processed backwards inside
helper function build_detached_freelist().
Lastly this also makes the code more robust, in error case like passing
NULL pointers in the array. Which were previously handled before commit
033745189b ("slub: add missing kmem cgroup support to
kmem_cache_free_bulk").
Fixes: 033745189b ("slub: add missing kmem cgroup support to kmem_cache_free_bulk")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 asm updates from Ingo Molnar:
"This is another big update. Main changes are:
- lots of x86 system call (and other traps/exceptions) entry code
enhancements. In particular the complex parts of the 64-bit entry
code have been migrated to C code as well, and a number of dusty
corners have been refreshed. (Andy Lutomirski)
- vDSO special mapping robustification and general cleanups (Andy
Lutomirski)
- cpufeature refactoring, cleanups and speedups (Borislav Petkov)
- lots of other changes ..."
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
x86/cpufeature: Enable new AVX-512 features
x86/entry/traps: Show unhandled signal for i386 in do_trap()
x86/entry: Call enter_from_user_mode() with IRQs off
x86/entry/32: Change INT80 to be an interrupt gate
x86/entry: Improve system call entry comments
x86/entry: Remove TIF_SINGLESTEP entry work
x86/entry/32: Add and check a stack canary for the SYSENTER stack
x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup
x86/entry: Only allocate space for tss_struct::SYSENTER_stack if needed
x86/entry: Vastly simplify SYSENTER TF (single-step) handling
x86/entry/traps: Clear DR6 early in do_debug() and improve the comment
x86/entry/traps: Clear TIF_BLOCKSTEP on all debug exceptions
x86/entry/32: Restore FLAGS on SYSEXIT
x86/entry/32: Filter NT and speed up AC filtering in SYSENTER
x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test
selftests/x86: In syscall_nt, test NT|TF as well
x86/asm-offsets: Remove PARAVIRT_enabled
x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled
uprobes: __create_xol_area() must nullify xol_mapping.fault
x86/cpufeature: Create a new synthetic cpu capability for machine check recovery
...
Pull ram resource handling changes from Ingo Molnar:
"Core kernel resource handling changes to support NVDIMM error
injection.
This tree introduces a new I/O resource type, IORESOURCE_SYSTEM_RAM,
for System RAM while keeping the current IORESOURCE_MEM type bit set
for all memory-mapped ranges (including System RAM) for backward
compatibility.
With this resource flag it no longer takes a strcmp() loop through the
resource tree to find "System RAM" resources.
The new resource type is then used to extend ACPI/APEI error injection
facility to also support NVDIMM"
* 'core-resources-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ACPI/EINJ: Allow memory error injection to NVDIMM
resource: Kill walk_iomem_res()
x86/kexec: Remove walk_iomem_res() call with GART type
x86, kexec, nvdimm: Use walk_iomem_res_desc() for iomem search
resource: Add walk_iomem_res_desc()
memremap: Change region_intersects() to take @flags and @desc
arm/samsung: Change s3c_pm_run_res() to use System RAM type
resource: Change walk_system_ram() to use System RAM type
drivers: Initialize resource entry to zero
xen, mm: Set IORESOURCE_SYSTEM_RAM to System RAM
kexec: Set IORESOURCE_SYSTEM_RAM for System RAM
arch: Set IORESOURCE_SYSTEM_RAM flag for System RAM
ia64: Set System RAM type and descriptor
x86/e820: Set System RAM type and descriptor
resource: Add I/O resource descriptor
resource: Handle resource flags properly
resource: Add System RAM resource type
When removing an element from the mempool, mark it as unpoisoned in KASAN
before verifying its contents for SLUB/SLAB debugging. Otherwise KASAN
will flag the reads checking the element use-after-free writes as
use-after-free reads.
Signed-off-by: Matthew Dawson <matthew@mjdsystems.ca>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace ENOTSUPP with EOPNOTSUPP. If hugepages are not supported, this
value is propagated to userspace. EOPNOTSUPP is part of uapi and is
widely supported by libc libraries.
It gives nicer message to user, rather than:
# cat /proc/sys/vm/nr_hugepages
cat: /proc/sys/vm/nr_hugepages: Unknown error 524
And also LTP's proc01 test was failing because this ret code (524)
was unexpected:
proc01 1 TFAIL : proc01.c:396: read failed: /proc/sys/vm/nr_hugepages: errno=???(524): Unknown error 524
proc01 2 TFAIL : proc01.c:396: read failed: /proc/sys/vm/nr_hugepages_mempolicy: errno=???(524): Unknown error 524
proc01 3 TFAIL : proc01.c:396: read failed: /proc/sys/vm/nr_overcommit_hugepages: errno=???(524): Unknown error 524
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't have native support of THP migration, so we have to split huge
page into small pages in order to migrate it to different node. This
includes PTE-mapped huge pages.
I made mistake in refcounting patchset: we don't actually split
PTE-mapped huge page in queue_pages_pte_range(), if we step on head
page.
The result is that the head page is queued for migration, but none of
tail pages: putting head page on queue takes pin on the page and any
subsequent attempts of split_huge_pages() would fail and we skip queuing
tail pages.
unmap_and_move_huge_page() will eventually split the huge pages, but
only one of 512 pages would get migrated.
Let's fix the situation.
Fixes: 248db92da1 ("migrate_pages: try to split pages on queuing")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Functions which the compiler has instrumented for ASAN place poison on
the stack shadow upon entry and remove this poison prior to returning.
In some cases (e.g. hotplug and idle), CPUs may exit the kernel a
number of levels deep in C code. If there are any instrumented
functions on this critical path, these will leave portions of the idle
thread stack shadow poisoned.
If a CPU returns to the kernel via a different path (e.g. a cold
entry), then depending on stack frame layout subsequent calls to
instrumented functions may use regions of the stack with stale poison,
resulting in (spurious) KASAN splats to the console.
Contemporary GCCs always add stack shadow poisoning when ASAN is
enabled, even when asked to not instrument a function [1], so we can't
simply annotate functions on the critical path to avoid poisoning.
Instead, this series explicitly removes any stale poison before it can
be hit. In the common hotplug case we clear the entire stack shadow in
common code, before a CPU is brought online.
On architectures which perform a cold return as part of cpu idle may
retain an architecture-specific amount of stack contents. To retain the
poison for this retained context, the arch code must call the core KASAN
code, passing a "watermark" stack pointer value beyond which shadow will
be cleared. Architectures which don't perform a cold return as part of
idle do not need any additional code.
This patch (of 3):
Functions which the compiler has instrumented for KASAN place poison on
the stack shadow upon entry and remove this poision prior to returning.
In some cases (e.g. hotplug and idle), CPUs may exit the kernel a number
of levels deep in C code. If there are any instrumented functions on this
critical path, these will leave portions of the stack shadow poisoned.
If a CPU returns to the kernel via a different path (e.g. a cold entry),
then depending on stack frame layout subsequent calls to instrumented
functions may use regions of the stack with stale poison, resulting in
(spurious) KASAN splats to the console.
To avoid this, we must clear stale poison from the stack prior to
instrumented functions being called. This patch adds functions to the
KASAN core for removing poison from (portions of) a task's stack. These
will be used by subsequent patches to avoid problems with hotplug and
idle.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit e1534ae950 ("mm: differentiate page_mapped() from
page_mapcount() for compound pages") changed the famous
BUG_ON(page_mapped(page)) in __delete_from_page_cache() to
VM_BUG_ON_PAGE(page_mapped(page)): which gives us more info when
CONFIG_DEBUG_VM=y, but nothing at all when not.
Although it has not usually been very helpul, being hit long after the
error in question, we do need to know if it actually happens on users'
systems; but reinstating a crash there is likely to be opposed :)
In the non-debug case, pr_alert("BUG: Bad page cache") plus dump_page(),
dump_stack(), add_taint() - I don't really believe LOCKDEP_NOW_UNRELIABLE,
but that seems to be the standard procedure now. Move that, or the
VM_BUG_ON_PAGE(), up before the deletion from tree: so that the
unNULLified page->mapping gives a little more information.
If the inode is being evicted (rather than truncated), it won't have any
vmas left, so it's safe(ish) to assume that the raised mapcount is
erroneous, and we can discount it from page_count to avoid leaking the
page (I'm less worried by leaking the occasional 4kB, than losing a
potential 2MB page with each 4kB page leaked).
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The warning message "killed due to inadequate hugepage pool" simply
indicates that SIGBUS was sent, not that the process was forcibly killed.
If the process has a signal handler installed does not fix the problem,
this message can rapidly spam the kernel log.
On my amd64 dev machine that does not have hugepages configured, I can
reproduce the repeated warnings easily by setting vm.nr_hugepages=2 (i.e.,
4 megabytes of huge pages) and running something that sets a signal
handler and forks, like
#include <sys/mman.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
sig_atomic_t counter = 10;
void handler(int signal)
{
if (counter-- == 0)
exit(0);
}
int main(void)
{
int status;
char *addr = mmap(NULL, 4 * 1048576, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
if (addr == MAP_FAILED) {perror("mmap"); return 1;}
*addr = 'x';
switch (fork()) {
case -1:
perror("fork"); return 1;
case 0:
signal(SIGBUS, handler);
*addr = 'x';
break;
default:
*addr = 'x';
wait(&status);
if (WIFSIGNALED(status)) {
psignal(WTERMSIG(status), "child");
}
break;
}
}
Signed-off-by: Geoffrey Thomas <geofft@ldpreload.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously calls to dax_writeback_mapping_range() for all DAX filesystems
(ext2, ext4 & xfs) were centralized in filemap_write_and_wait_range().
dax_writeback_mapping_range() needs a struct block_device, and it used
to get that from inode->i_sb->s_bdev. This is correct for normal inodes
mounted on ext2, ext4 and XFS filesystems, but is incorrect for DAX raw
block devices and for XFS real-time files.
Instead, call dax_writeback_mapping_range() directly from the filesystem
->writepages function so that it can supply us with a valid block
device. This also fixes DAX code to properly flush caches in response
to sync(2).
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 4167e9b2cf ("mm: remove GFP_THISNODE") removed the GFP_THISNODE
flag combination due to confusing semantics. It noted that
alloc_misplaced_dst_page() was one such user after changes made by
commit e97ca8e5b8 ("mm: fix GFP_THISNODE callers and clarify").
Unfortunately when GFP_THISNODE was removed, users of
alloc_misplaced_dst_page() started waking kswapd and entering direct
reclaim because the wrong GFP flags are cleared. The consequence is
that workloads that used to fit into memory now get reclaimed which is
addressed by this patch.
The problem can be demonstrated with "mutilate" that exercises memcached
which is software dedicated to memory object caching. The configuration
uses 80% of memory and is run 3 times for varying numbers of clients.
The results on a 4-socket NUMA box are
mutilate
4.4.0 4.4.0
vanilla numaswap-v1
Hmean 1 8394.71 ( 0.00%) 8395.32 ( 0.01%)
Hmean 4 30024.62 ( 0.00%) 34513.54 ( 14.95%)
Hmean 7 32821.08 ( 0.00%) 70542.96 (114.93%)
Hmean 12 55229.67 ( 0.00%) 93866.34 ( 69.96%)
Hmean 21 39438.96 ( 0.00%) 85749.21 (117.42%)
Hmean 30 37796.10 ( 0.00%) 50231.49 ( 32.90%)
Hmean 47 18070.91 ( 0.00%) 38530.13 (113.22%)
The metric is queries/second with the more the better. The results are
way outside of the noise and the reason for the improvement is obvious
from some of the vmstats
4.4.0 4.4.0
vanillanumaswap-v1r1
Minor Faults 1929399272 2146148218
Major Faults 19746529 3567
Swap Ins 57307366 9913
Swap Outs 50623229 17094
Allocation stalls 35909 443
DMA allocs 0 0
DMA32 allocs 72976349 170567396
Normal allocs 5306640898 5310651252
Movable allocs 0 0
Direct pages scanned 404130893 799577
Kswapd pages scanned 160230174 0
Kswapd pages reclaimed 55928786 0
Direct pages reclaimed 1843936 41921
Page writes file 2391 0
Page writes anon 50623229 17094
The vanilla kernel is swapping like crazy with large amounts of direct
reclaim and kswapd activity. The figures are aggregate but it's known
that the bad activity is throughout the entire test.
Note that simple streaming anon/file memory consumers also see this
problem but it's not as obvious. In those cases, kswapd is awake when
it should not be.
As there are at least two reclaim-related bugs out there, it's worth
spelling out the user-visible impact. This patch only addresses bugs
related to excessive reclaim on NUMA hardware when the working set is
larger than a NUMA node. There is a bug related to high kswapd CPU
usage but the reports are against laptops and other UMA hardware and is
not addressed by this patch.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org> [4.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
