Admin could reset zram during I/O operation going on so we have used
zram->init_lock as read-side lock in I/O path to prevent sudden zram
meta freeing.
However, the init_lock is really troublesome. We can't do call
zram_meta_alloc under init_lock due to lockdep splat because
zram_rw_page is one of the function under reclaim path and hold it as
read_lock while other places in process context hold it as write_lock.
So, we have used allocation out of the lock to avoid lockdep warn but
it's not good for readability and fainally, I met another lockdep splat
between init_lock and cpu_hotplug from kmem_cache_destroy during working
zsmalloc compaction. :(
Yes, the ideal is to remove horrible init_lock of zram in rw path. This
patch removes it in rw path and instead, add atomic refcount for meta
lifetime management and completion to free meta in process context.
It's important to free meta in process context because some of resource
destruction needs mutex lock, which could be held if we releases the
resource in reclaim context so it's deadlock, again.
As a bonus, we could remove init_done check in rw path because
zram_meta_get will do a role for it, instead.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Ganesh Mahendran <opensource.ganesh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
bd_holders is increased only when user open the device file as FMODE_EXCL
so if something opens zram0 as !FMODE_EXCL and request I/O while another
user reset zram0, we can see following warning.
zram0: detected capacity change from 0 to 64424509440
Buffer I/O error on dev zram0, logical block 180823, lost async page write
Buffer I/O error on dev zram0, logical block 180824, lost async page write
Buffer I/O error on dev zram0, logical block 180825, lost async page write
Buffer I/O error on dev zram0, logical block 180826, lost async page write
Buffer I/O error on dev zram0, logical block 180827, lost async page write
Buffer I/O error on dev zram0, logical block 180828, lost async page write
Buffer I/O error on dev zram0, logical block 180829, lost async page write
Buffer I/O error on dev zram0, logical block 180830, lost async page write
Buffer I/O error on dev zram0, logical block 180831, lost async page write
Buffer I/O error on dev zram0, logical block 180832, lost async page write
------------[ cut here ]------------
WARNING: CPU: 11 PID: 1996 at fs/block_dev.c:57 __blkdev_put+0x1d7/0x210()
Modules linked in:
CPU: 11 PID: 1996 Comm: dd Not tainted 3.19.0-rc6-next-20150202+ #1125
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
dump_stack+0x45/0x57
warn_slowpath_common+0x8a/0xc0
warn_slowpath_null+0x1a/0x20
__blkdev_put+0x1d7/0x210
blkdev_put+0x50/0x130
blkdev_close+0x25/0x30
__fput+0xdf/0x1e0
____fput+0xe/0x10
task_work_run+0xa7/0xe0
do_notify_resume+0x49/0x60
int_signal+0x12/0x17
---[ end trace 274fbbc5664827d2 ]---
The warning comes from bdev_write_node in blkdev_put path.
static void bdev_write_inode(struct inode *inode)
{
spin_lock(&inode->i_lock);
while (inode->i_state & I_DIRTY) {
spin_unlock(&inode->i_lock);
WARN_ON_ONCE(write_inode_now(inode, true)); <========= here.
spin_lock(&inode->i_lock);
}
spin_unlock(&inode->i_lock);
}
The reason is dd process encounters I/O fails due to sudden block device
disappear so in filemap_check_errors in __writeback_single_inode returns
-EIO.
If we check bd_openers instead of bd_holders, we could address the
problem. When I see the brd, it already have used it rather than
bd_holders so although I'm not a expert of block layer, it seems to be
better.
I can make following warning with below simple script. In addition, I
added msleep(2000) below set_capacity(zram->disk, 0) after applying your
patch to make window huge(Kudos to Ganesh!)
script:
echo $((60<<30)) > /sys/block/zram0/disksize
setsid dd if=/dev/zero of=/dev/zram0 &
sleep 1
setsid echo 1 > /sys/block/zram0/reset
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Ganesh Mahendran <opensource.ganesh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need to return set_capacity(disk, 0) from reset_store() back to
zram_reset_device(), a catch by Ganesh Mahendran. Potentially, we can
race set_capacity() calls from init and reset paths.
The problem is that zram_reset_device() is also getting called from
zram_exit(), which performs operations in misleading reversed order -- we
first create_device() and then init it, while zram_exit() perform
destroy_device() first and then does zram_reset_device(). This is done to
remove sysfs group before we reset device, so we can continue with device
reset/destruction not being raced by sysfs attr write (f.e. disksize).
Apart from that, destroy_device() releases zram->disk (but we still have
->disk pointer), so we cannot acces zram->disk in later
zram_reset_device() call, which may cause additional errors in the future.
So, this patch rework and cleanup destroy path.
1) remove several unneeded goto labels in zram_init()
2) factor out zram_init() error path and zram_exit() into
destroy_devices() function, which takes the number of devices to
destroy as its argument.
3) remove sysfs group in destroy_devices() first, so we can reorder
operations -- reset device (as expected) goes before disk destroy and
queue cleanup. So we can always access ->disk in zram_reset_device().
4) and, finally, return set_capacity() back under ->init_lock.
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ganesh Mahendran was the first one who proposed to use bdev->bd_mutex to
avoid ->bd_holders race condition:
CPU0 CPU1
umount /* zram->init_done is true */
reset_store()
bdev->bd_holders == 0 mount
... zram_make_request()
zram_reset_device()
However, his solution required some considerable amount of code movement,
which we can avoid.
Apart from using bdev->bd_mutex in reset_store(), this patch also
simplifies zram_reset_device().
zram_reset_device() has a bool parameter reset_capacity which tells it
whether disk capacity and itself disk should be reset. There are two
zram_reset_device() callers:
-- zram_exit() passes reset_capacity=false
-- reset_store() passes reset_capacity=true
So we can move reset_capacity-sensitive work out of zram_reset_device()
and perform it unconditionally in reset_store(). This also lets us drop
reset_capacity parameter from zram_reset_device() and pass zram pointer
only.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zram_meta_alloc() and zram_meta_free() are a pair. In
zram_meta_alloc(), meta table is allocated. So it it better to free it
in zram_meta_free().
Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vmstat interfaces are good at hiding negative counts (at least when
CONFIG_SMP); but if you peer behind the curtain, you find that
nr_isolated_anon and nr_isolated_file soon go negative, and grow ever
more negative: so they can absorb larger and larger numbers of isolated
pages, yet still appear to be zero.
I'm happy to avoid a congestion_wait() when too_many_isolated() myself;
but I guess it's there for a good reason, in which case we ought to get
too_many_isolated() working again.
The imbalance comes from isolate_migratepages()'s ISOLATE_ABORT case:
putback_movable_pages() decrements the NR_ISOLATED counts, but we forgot
to call acct_isolated() to increment them.
It is possible that the bug whcih this patch fixes could cause OOM kills
when the system still has a lot of reclaimable page cache.
Fixes: edc2ca6124 ("mm, compaction: move pageblock checks up from isolate_migratepages_range()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org> [3.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A race condition starts to be visible in recent mmotm, where a PG_hwpoison
flag is set on a migration source page *before* it's back in buddy page
poo= l.
This is problematic because no page flag is supposed to be set when
freeing (see __free_one_page().) So the user-visible effect of this race
is that it could trigger the BUG_ON() when soft-offlining is called.
The root cause is that we call lru_add_drain_all() to make sure that the
page is in buddy, but that doesn't work because this function just
schedule= s a work item and doesn't wait its completion.
drain_all_pages() does drainin= g directly, so simply dropping
lru_add_drain_all() solves this problem.
Fixes: f15bdfa802 ("mm/memory-failure.c: fix memory leak in successful soft offlining")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Cc: <stable@vger.kernel.org> [3.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For whatever reason, generic_access_phys() only remaps one page, but
actually allows to access arbitrary size. It's quite easy to trigger
large reads, like printing out large structure with gdb, which leads to a
crash. Fix it by remapping correct size.
Fixes: 28b2ee20c7 ("access_process_vm device memory infrastructure")
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only caller of cpuset_init_current_mems_allowed is the __init
annotated build_all_zonelists_init, so we can also make the former __init.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mminit_loglevel is only referenced from __init and __meminit functions, so
we can mark it __meminitdata.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only caller of mminit_verify_zonelist is build_all_zonelists_init,
which is annotated with __init, so it should be safe to also mark the
former as __init, saving ~400 bytes of .text.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pulling the code protected by if (system_state == SYSTEM_BOOTING) into
its own helper allows us to shrink .text a little. This relies on
build_all_zonelists already having a __ref annotation. Add a comment
explaining why so one doesn't have to track it down through git log.
The real saving comes in 3/5, ("mm/mm_init.c: Mark mminit_verify_zonelist
as __init"), where we save about 400 bytes
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All users of mminit_dprintk pass a compile-time constant as level, so this
just makes gcc emit a single printk call instead of two.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm->nr_pmds doesn't make sense on !MMU configurations
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move memcg_socket_limit_enabled decrement to tcp_destroy_cgroup (called
from memcg_destroy_kmem -> mem_cgroup_sockets_destroy) and zap a bunch of
wrapper functions.
Although this patch moves static keys decrement from __mem_cgroup_free to
mem_cgroup_css_free, it does not introduce any functional changes, because
the keys are incremented on setting the limit (tcp or kmem), which can
only happen after successful mem_cgroup_css_online.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, freepage isolation in one pageblock doesn't consider how many
freepages we isolate. When I traced flow of compaction, compaction
sometimes isolates more than 256 freepages to migrate just 32 pages.
In this patch, freepage isolation is stopped at the point that we
have more isolated freepage than isolated page for migration. This
results in slowing down free page scanner and make compaction success
rate higher.
stress-highalloc test in mmtests with non movable order 7 allocation shows
increase of compaction success rate.
Compaction success rate (Compaction success * 100 / Compaction stalls, %)
27.13 : 31.82
pfn where both scanners meets on compaction complete
(separate test due to enormous tracepoint buffer)
(zone_start=4096, zone_end=1048576)
586034 : 654378
In fact, I didn't fully understand why this patch results in such good
result. There was a guess that not used freepages are released to pcp list
and on next compaction trial we won't isolate them again so compaction
success rate would decrease. To prevent this effect, I tested with adding
pcp drain code on release_freepages(), but, it has no good effect.
Anyway, this patch reduces waste time to isolate unneeded freepages so
seems reasonable.
Vlastimil said:
: I briefly tried it on top of the pivot-changing series and with order-9
: allocations it reduced free page scanned counter by almost 10%. No effect
: on success rates (maybe because pivot changing already took care of the
: scanners meeting problem) but the scanning reduction is good on its own.
:
: It also explains why e14c720efd ("mm, compaction: remember position
: within pageblock in free pages scanner") had less than expected
: improvements. It would only actually stop within pageblock in case of
: async compaction detecting contention. I guess that's also why the
: infinite loop problem fixed by 1d5bfe1ffb affected so relatively few
: people.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
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>
What we want to check here is whether there is highorder freepage in buddy
list of other migratetype in order to steal it without fragmentation.
But, current code just checks cc->order which means allocation request
order. So, this is wrong.
Without this fix, non-movable synchronous compaction below pageblock order
would not stopped until compaction is complete, because migratetype of
most pageblocks are movable and high order freepage made by compaction is
usually on movable type buddy list.
There is some report related to this bug. See below link.
http://www.spinics.net/lists/linux-mm/msg81666.html
Although the issued system still has load spike comes from compaction,
this makes that system completely stable and responsive according to his
report.
stress-highalloc test in mmtests with non movable order 7 allocation
doesn't show any notable difference in allocation success rate, but, it
shows more compaction success rate.
Compaction success rate (Compaction success * 100 / Compaction stalls, %)
18.47 : 28.94
Fixes: 1fb3f8ca0e ("mm: compaction: capture a suitable high-order page immediately when it is made available")
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org> [3.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To speed up further allocations SLUB may store empty slabs in per cpu/node
partial lists instead of freeing them immediately. This prevents per
memcg caches destruction, because kmem caches created for a memory cgroup
are only destroyed after the last page charged to the cgroup is freed.
To fix this issue, this patch resurrects approach first proposed in [1].
It forbids SLUB to cache empty slabs after the memory cgroup that the
cache belongs to was destroyed. It is achieved by setting kmem_cache's
cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so
that it would drop frozen empty slabs immediately if cpu_partial = 0.
The runtime overhead is minimal. From all the hot functions, we only
touch relatively cold put_cpu_partial(): we make it call
unfreeze_partials() after freezing a slab that belongs to an offline
memory cgroup. Since slab freezing exists to avoid moving slabs from/to a
partial list on free/alloc, and there can't be allocations from dead
caches, it shouldn't cause any overhead. We do have to disable preemption
for put_cpu_partial() to achieve that though.
The original patch was accepted well and even merged to the mm tree.
However, I decided to withdraw it due to changes happening to the memcg
core at that time. I had an idea of introducing per-memcg shrinkers for
kmem caches, but now, as memcg has finally settled down, I do not see it
as an option, because SLUB shrinker would be too costly to call since SLUB
does not keep free slabs on a separate list. Besides, we currently do not
even call per-memcg shrinkers for offline memcgs. Overall, it would
introduce much more complexity to both SLUB and memcg than this small
patch.
Regarding to SLAB, there's no problem with it, because it shrinks
per-cpu/node caches periodically. Thanks to list_lru reparenting, we no
longer keep entries for offline cgroups in per-memcg arrays (such as
memcg_cache_params->memcg_caches), so we do not have to bother if a
per-memcg cache will be shrunk a bit later than it could be.
[1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650
Signed-off-by: Vladimir Davydov <vdavydov@parallels.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is supposed to return 0 if the cache has no remaining objects and 1
otherwise, while currently it always returns 0. Fix it.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLUB's version of __kmem_cache_shrink() not only removes empty slabs, but
also tries to rearrange the partial lists to place slabs filled up most to
the head to cope with fragmentation. To achieve that, it allocates a
temporary array of lists used to sort slabs by the number of objects in
use. If the allocation fails, the whole procedure is aborted.
This is unacceptable for the kernel memory accounting extension of the
memory cgroup, where we want to make sure that kmem_cache_shrink()
successfully discarded empty slabs. Although the allocation failure is
utterly unlikely with the current page allocator implementation, which
retries GFP_KERNEL allocations of order <= 2 infinitely, it is better not
to rely on that.
This patch therefore makes __kmem_cache_shrink() allocate the array on
stack instead of calling kmalloc, which may fail. The array size is
chosen to be equal to 32, because most SLUB caches store not more than 32
objects per slab page. Slab pages with <= 32 free objects are sorted
using the array by the number of objects in use and promoted to the head
of the partial list, while slab pages with > 32 free objects are left in
the end of the list without any ordering imposed on them.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now, the only reason to keep kmemcg_id till css free is list_lru, which
uses it to distribute elements between per-memcg lists. However, it can
be easily sorted out - we only need to change kmemcg_id of an offline
cgroup to its parent's id, making further list_lru_add()'s add elements to
the parent's list, and then move all elements from the offline cgroup's
list to the one of its parent. It will work, because a racing
list_lru_del() does not need to know the list it is deleting the element
from. It can decrement the wrong nr_items counter though, but the ongoing
reparenting will fix it. After list_lru reparenting is done we are free
to release kmemcg_id saving a valuable slot in a per-memcg array for new
cgroups.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the isolate callback passed to the list_lru_walk family of
functions is supposed to just delete an item from the list upon returning
LRU_REMOVED or LRU_REMOVED_RETRY, while nr_items counter is fixed by
__list_lru_walk_one after the callback returns. Since the callback is
allowed to drop the lock after removing an item (it has to return
LRU_REMOVED_RETRY then), the nr_items can be less than the actual number
of elements on the list even if we check them under the lock. This makes
it difficult to move items from one list_lru_one to another, which is
required for per-memcg list_lru reparenting - we can't just splice the
lists, we have to move entries one by one.
This patch therefore introduces helpers that must be used by callback
functions to isolate items instead of raw list_del/list_move. These are
list_lru_isolate and list_lru_isolate_move. They not only remove the
entry from the list, but also fix the nr_items counter, making sure
nr_items always reflects the actual number of elements on the list if
checked under the appropriate lock.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need to look up a kmem_cache in ->memcg_params.memcg_caches arrays only
on allocations, so there is no need to have the array entries set until
css free - we can clear them on css offline. This will allow us to reuse
array entries more efficiently and avoid costly array relocations.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, we use mem_cgroup->kmemcg_id to guarantee kmem_cache->name
uniqueness. This is correct, because kmemcg_id is only released on css
free after destroying all per memcg caches.
However, I am going to change that and release kmemcg_id on css offline,
because it is not wise to keep it for so long, wasting valuable entries of
memcg_cache_params->memcg_caches arrays. Therefore, to preserve cache
name uniqueness, let us switch to css->id.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, we release css->id in css_release_work_fn, right before calling
css_free callback, so that when css_free is called, the id may have
already been reused for a new cgroup.
I am going to use css->id to create unique names for per memcg kmem
caches. Since kmem caches are destroyed only on css_free, I need css->id
to be freed after css_free was called to avoid name clashes. This patch
therefore moves css->id removal to css_free_work_fn. To prevent
css_from_id from returning a pointer to a stale css, it makes
css_release_work_fn replace the css ptr at css_idr:css->id with NULL.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sometimes, we need to iterate over all memcg copies of a particular root
kmem cache. Currently, we use memcg_cache_params->memcg_caches array for
that, because it contains all existing memcg caches.
However, it's a bad practice to keep all caches, including those that
belong to offline cgroups, in this array, because it will be growing
beyond any bounds then. I'm going to wipe away dead caches from it to
save space. To still be able to perform iterations over all memcg caches
of the same kind, let us link them into a list.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, kmem_cache stores a pointer to struct memcg_cache_params
instead of embedding it. The rationale is to save memory when kmem
accounting is disabled. However, the memcg_cache_params has shrivelled
drastically since it was first introduced:
* Initially:
struct memcg_cache_params {
bool is_root_cache;
union {
struct kmem_cache *memcg_caches[0];
struct {
struct mem_cgroup *memcg;
struct list_head list;
struct kmem_cache *root_cache;
bool dead;
atomic_t nr_pages;
struct work_struct destroy;
};
};
};
* Now:
struct memcg_cache_params {
bool is_root_cache;
union {
struct {
struct rcu_head rcu_head;
struct kmem_cache *memcg_caches[0];
};
struct {
struct mem_cgroup *memcg;
struct kmem_cache *root_cache;
};
};
};
So the memory saving does not seem to be a clear win anymore.
OTOH, keeping a pointer to memcg_cache_params struct instead of embedding
it results in touching one more cache line on kmem alloc/free hot paths.
Besides, it makes linking kmem caches in a list chained by a field of
struct memcg_cache_params really painful due to a level of indirection,
while I want to make them linked in the following patch. That said, let
us embed it.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
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: Dave Chinner <david@fromorbit.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In super_cache_scan() we divide the number of objects of particular type
by the total number of objects in order to distribute pressure among As a
result, in some corner cases we can get nr_to_scan=0 even if there are
some objects to reclaim, e.g. dentries=1, inodes=1, fs_objects=1,
nr_to_scan=1/3=0.
This is unacceptable for per memcg kmem accounting, because this means
that some objects may never get reclaimed after memcg death, preventing it
from being freed.
This patch therefore assures that super_cache_scan() will scan at least
one object of each type if any.
[akpm@linux-foundation.org: add comment]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now, to make any list_lru-based shrinker memcg aware we should only
initialize its list_lru as memcg aware. Let's do it for the general FS
shrinker (super_block::s_shrink).
There are other FS-specific shrinkers that use list_lru for storing
objects, such as XFS and GFS2 dquot cache shrinkers, but since they
reclaim objects that are shared among different cgroups, there is no point
making them memcg aware. It's a big question whether we should account
them to memcg at all.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several FS shrinkers, including super_block::s_shrink, that
keep reclaimable objects in the list_lru structure. Hence to turn them
to memcg-aware shrinkers, it is enough to make list_lru per-memcg.
This patch does the trick. It adds an array of lru lists to the
list_lru_node structure (per-node part of the list_lru), one for each
kmem-active memcg, and dispatches every item addition or removal to the
list corresponding to the memcg which the item is accounted to. So now
the list_lru structure is not just per node, but per node and per memcg.
Not all list_lrus need this feature, so this patch also adds a new
method, list_lru_init_memcg, which initializes a list_lru as memcg
aware. Otherwise (i.e. if initialized with old list_lru_init), the
list_lru won't have per memcg lists.
Just like per memcg caches arrays, the arrays of per-memcg lists are
indexed by memcg_cache_id, so we must grow them whenever
memcg_nr_cache_ids is increased. So we introduce a callback,
memcg_update_all_list_lrus, invoked by memcg_alloc_cache_id if the id
space is full.
The locking is implemented in a manner similar to lruvecs, i.e. we have
one lock per node that protects all lists (both global and per cgroup) on
the node.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To make list_lru memcg aware, we need all list_lrus to be kept on a list
protected by a mutex, so that we could sleep while walking over the
list.
Therefore after this change list_lru_destroy may sleep. Fortunately,
there is only one user that calls it from an atomic context - it's
put_super - and we can easily fix it by calling list_lru_destroy before
put_super in destroy_locked_super - anyway we don't longer need lrus by
that time.
Another point that should be noted is that list_lru_destroy is allowed
to be called on an uninitialized zeroed-out object, in which case it is
a no-op. Before this patch this was guaranteed by kfree, but now we
need an explicit check there.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The active_nodes mask allows us to skip empty nodes when walking over
list_lru items from all nodes in list_lru_count/walk. However, these
functions are never called from hot paths, so it doesn't seem we need
such kind of optimization there. OTOH, removing the mask will make it
easier to make list_lru per-memcg.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need a stable value of memcg_nr_cache_ids in kmem_cache_create()
(memcg_alloc_cache_params() wants it for root caches), where we only
hold the slab_mutex and no memcg-related locks. As a result, we have to
update memcg_nr_cache_ids under the slab_mutex, which we can only take
on the slab's side (see memcg_update_array_size). This looks awkward
and will become even worse when per-memcg list_lru is introduced, which
also wants stable access to memcg_nr_cache_ids.
To get rid of this dependency between the memcg_nr_cache_ids and the
slab_mutex, this patch introduces a special rwsem. The rwsem is held
for writing during memcg_caches arrays relocation and memcg_nr_cache_ids
updates. Therefore one can take it for reading to get a stable access
to memcg_caches arrays and/or memcg_nr_cache_ids.
Currently the semaphore is taken for reading only from
kmem_cache_create, right before taking the slab_mutex, so right now
there's no much point in using rwsem instead of mutex. However, once
list_lru is made per-memcg it will allow list_lru initializations to
proceed concurrently.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg_limited_groups_array_size, which defines the size of memcg_caches
arrays, sounds rather cumbersome. Also it doesn't point anyhow that
it's related to kmem/caches stuff. So let's rename it to
memcg_nr_cache_ids. It's concise and points us directly to
memcg_cache_id.
Also, rename kmem_limited_groups to memcg_cache_ida.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds SHRINKER_MEMCG_AWARE flag. If a shrinker has this flag
set, it will be called per memory cgroup. The memory cgroup to scan
objects from is passed in shrink_control->memcg. If the memory cgroup
is NULL, a memcg aware shrinker is supposed to scan objects from the
global list. Unaware shrinkers are only called on global pressure with
memcg=NULL.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We are going to make FS shrinkers memcg-aware. To achieve that, we will
have to pass the memcg to scan to the nr_cached_objects and
free_cached_objects VFS methods, which currently take only the NUMA node
to scan. Since the shrink_control structure already holds the node, and
the memcg to scan will be added to it when we introduce memcg-aware
vmscan, let us consolidate the methods' arguments in this structure to
keep things clean.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kmem accounting of memcg is unusable now, because it lacks slab shrinker
support. That means when we hit the limit we will get ENOMEM w/o any
chance to recover. What we should do then is to call shrink_slab, which
would reclaim old inode/dentry caches from this cgroup. This is what
this patch set is intended to do.
Basically, it does two things. First, it introduces the notion of
per-memcg slab shrinker. A shrinker that wants to reclaim objects per
cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be
passed the memory cgroup to scan from in shrink_control->memcg. For
such shrinkers shrink_slab iterates over the whole cgroup subtree under
the target cgroup and calls the shrinker for each kmem-active memory
cgroup.
Secondly, this patch set makes the list_lru structure per-memcg. It's
done transparently to list_lru users - everything they have to do is to
tell list_lru_init that they want memcg-aware list_lru. Then the
list_lru will automatically distribute objects among per-memcg lists
basing on which cgroup the object is accounted to. This way to make FS
shrinkers (icache, dcache) memcg-aware we only need to make them use
memcg-aware list_lru, and this is what this patch set does.
As before, this patch set only enables per-memcg kmem reclaim when the
pressure goes from memory.limit, not from memory.kmem.limit. Handling
memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and
it is still unclear whether we will have this knob in the unified
hierarchy.
This patch (of 9):
NUMA aware slab shrinkers use the list_lru structure to distribute
objects coming from different NUMA nodes to different lists. Whenever
such a shrinker needs to count or scan objects from a particular node,
it issues commands like this:
count = list_lru_count_node(lru, sc->nid);
freed = list_lru_walk_node(lru, sc->nid, isolate_func,
isolate_arg, &sc->nr_to_scan);
where sc is an instance of the shrink_control structure passed to it
from vmscan.
To simplify this, let's add special list_lru functions to be used by
shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which
consolidate the nid and nr_to_scan arguments in the shrink_control
structure.
This will also allow us to avoid patching shrinkers that use list_lru
when we make shrink_slab() per-memcg - all we will have to do is extend
the shrink_control structure to include the target memcg and make
list_lru_shrink_{count,walk} handle this appropriately.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If a PTE or PMD is already marked NUMA when scanning to mark entries for
NUMA hinting then it is not necessary to update the entry and incur a TLB
flush penalty. Avoid the avoidhead where possible.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.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>
pte_protnone_numa is only safe to use after VMA checks for PROT_NONE are
complete. Treating a real PROT_NONE PTE as a NUMA hinting fault is going
to result in strangeness so add a check for it. BUG_ON looks like
overkill but if this is hit then it's a serious bug that could result in
corruption so do not even try recovering. It would have been more
comprehensive to check VMA flags in pte_protnone_numa but it would have
made the API ugly just for a debugging check.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.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>
Commit b38af4721f ("x86,mm: fix pte_special versus pte_numa") adjusted
the pte_special check to take into account that a special pte had
SPECIAL and neither PRESENT nor PROTNONE. Now that NUMA hinting PTEs
are no longer modifying _PAGE_PRESENT it should be safe to restore the
original pte_special behaviour.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.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>
Faults on the huge zero page are pointless and there is a BUG_ON to catch
them during fault time. This patch reintroduces a check that avoids
marking the zero page PAGE_NONE.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.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>
This patch removes the NUMA PTE bits and associated helpers. As a
side-effect it increases the maximum possible swap space on x86-64.
One potential source of problems is races between the marking of PTEs
PROT_NONE, NUMA hinting faults and migration. It must be guaranteed that
a PTE being protected is not faulted in parallel, seen as a pte_none and
corrupting memory. The base case is safe but transhuge has problems in
the past due to an different migration mechanism and a dependance on page
lock to serialise migrations and warrants a closer look.
task_work hinting update parallel fault
------------------------ --------------
change_pmd_range
change_huge_pmd
__pmd_trans_huge_lock
pmdp_get_and_clear
__handle_mm_fault
pmd_none
do_huge_pmd_anonymous_page
read? pmd_lock blocks until hinting complete, fail !pmd_none test
write? __do_huge_pmd_anonymous_page acquires pmd_lock, checks pmd_none
pmd_modify
set_pmd_at
task_work hinting update parallel migration
------------------------ ------------------
change_pmd_range
change_huge_pmd
__pmd_trans_huge_lock
pmdp_get_and_clear
__handle_mm_fault
do_huge_pmd_numa_page
migrate_misplaced_transhuge_page
pmd_lock waits for updates to complete, recheck pmd_same
pmd_modify
set_pmd_at
Both of those are safe and the case where a transhuge page is inserted
during a protection update is unchanged. The case where two processes try
migrating at the same time is unchanged by this series so should still be
ok. I could not find a case where we are accidentally depending on the
PTE not being cleared and flushed. If one is missed, it'll manifest as
corruption problems that start triggering shortly after this series is
merged and only happen when NUMA balancing is enabled.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ppc64 should not be depending on DSISR_PROTFAULT and it's unexpected if
they are triggered. This patch adds warnings just in case they are being
accidentally depended upon.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
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>
Convert existing users of pte_numa and friends to the new helper. Note
that the kernel is broken after this patch is applied until the other page
table modifiers are also altered. This patch layout is to make review
easier.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.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>
Automatic NUMA balancing depends on being able to protect PTEs to trap a
fault and gather reference locality information. Very broadly speaking
it would mark PTEs as not present and use another bit to distinguish
between NUMA hinting faults and other types of faults. It was
universally loved by everybody and caused no problems whatsoever. That
last sentence might be a lie.
This series is very heavily based on patches from Linus and Aneesh to
replace the existing PTE/PMD NUMA helper functions with normal change
protections. I did alter and add parts of it but I consider them
relatively minor contributions. At their suggestion, acked-bys are in
there but I've no problem converting them to Signed-off-by if requested.
AFAIK, this has received no testing on ppc64 and I'm depending on Aneesh
for that. I tested trinity under kvm-tool and passed and ran a few
other basic tests. At the time of writing, only the short-lived tests
have completed but testing of V2 indicated that long-term testing had no
surprises. In most cases I'm leaving out detail as it's not that
interesting.
specjbb single JVM: There was negligible performance difference in the
benchmark itself for short runs. However, system activity is
higher and interrupts are much higher over time -- possibly TLB
flushes. Migrations are also higher. Overall, this is more overhead
but considering the problems faced with the old approach I think
we just have to suck it up and find another way of reducing the
overhead.
specjbb multi JVM: Negligible performance difference to the actual benchmark
but like the single JVM case, the system overhead is noticeably
higher. Again, interrupts are a major factor.
autonumabench: This was all over the place and about all that can be
reasonably concluded is that it's different but not necessarily
better or worse.
autonumabench
3.18.0-rc5 3.18.0-rc5
mmotm-20141119 protnone-v3r3
User NUMA01 32380.24 ( 0.00%) 21642.92 ( 33.16%)
User NUMA01_THEADLOCAL 22481.02 ( 0.00%) 22283.22 ( 0.88%)
User NUMA02 3137.00 ( 0.00%) 3116.54 ( 0.65%)
User NUMA02_SMT 1614.03 ( 0.00%) 1543.53 ( 4.37%)
System NUMA01 322.97 ( 0.00%) 1465.89 (-353.88%)
System NUMA01_THEADLOCAL 91.87 ( 0.00%) 49.32 ( 46.32%)
System NUMA02 37.83 ( 0.00%) 14.61 ( 61.38%)
System NUMA02_SMT 7.36 ( 0.00%) 7.45 ( -1.22%)
Elapsed NUMA01 716.63 ( 0.00%) 599.29 ( 16.37%)
Elapsed NUMA01_THEADLOCAL 553.98 ( 0.00%) 539.94 ( 2.53%)
Elapsed NUMA02 83.85 ( 0.00%) 83.04 ( 0.97%)
Elapsed NUMA02_SMT 86.57 ( 0.00%) 79.15 ( 8.57%)
CPU NUMA01 4563.00 ( 0.00%) 3855.00 ( 15.52%)
CPU NUMA01_THEADLOCAL 4074.00 ( 0.00%) 4136.00 ( -1.52%)
CPU NUMA02 3785.00 ( 0.00%) 3770.00 ( 0.40%)
CPU NUMA02_SMT 1872.00 ( 0.00%) 1959.00 ( -4.65%)
System CPU usage of NUMA01 is worse but it's an adverse workload on this
machine so I'm reluctant to conclude that it's a problem that matters. On
the other workloads that are sensible on this machine, system CPU usage is
great. Overall time to complete the benchmark is comparable
3.18.0-rc5 3.18.0-rc5
mmotm-20141119protnone-v3r3
User 59612.50 48586.44
System 460.22 1537.45
Elapsed 1442.20 1304.29
NUMA alloc hit 5075182 5743353
NUMA alloc miss 0 0
NUMA interleave hit 0 0
NUMA alloc local 5075174 5743339
NUMA base PTE updates 637061448 443106883
NUMA huge PMD updates 1243434 864747
NUMA page range updates 1273699656 885857347
NUMA hint faults 1658116 1214277
NUMA hint local faults 959487 754113
NUMA hint local percent 57 62
NUMA pages migrated 5467056 61676398
The NUMA pages migrated look terrible but when I looked at a graph of the
activity over time I see that the massive spike in migration activity was
during NUMA01. This correlates with high system CPU usage and could be
simply down to bad luck but any modifications that affect that workload
would be related to scan rates and migrations, not the protection
mechanism. For all other workloads, migration activity was comparable.
Overall, headline performance figures are comparable but the overhead is
higher, mostly in interrupts. To some extent, higher overhead from this
approach was anticipated but not to this degree. It's going to be
necessary to reduce this again with a separate series in the future. It's
still worth going ahead with this series though as it's likely to avoid
constant headaches with Xen and is probably easier to maintain.
This patch (of 10):
A transhuge NUMA hinting fault may find the page is migrating and should
wait until migration completes. The check is race-prone because the pmd
is deferenced outside of the page lock and while the race is tiny, it'll
be larger if the PMD is cleared while marking PMDs for hinting fault.
This patch closes the race.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.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>
stacking ontop of blk-mq devices. This blk-mq support changes the
model request-based DM uses for cloning a request to relying on
calling blk_get_request() directly from the underlying blk-mq device.
Early consumer of this code is Intel's emerging NVMe hardware; thanks
to Keith Busch for working on, and pushing for, these changes.
- A few other small fixes and cleanups across other DM targets.
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Merge tag 'dm-3.20-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper changes from Mike Snitzer:
- The most significant change this cycle is request-based DM now
supports stacking ontop of blk-mq devices. This blk-mq support
changes the model request-based DM uses for cloning a request to
relying on calling blk_get_request() directly from the underlying
blk-mq device.
An early consumer of this code is Intel's emerging NVMe hardware;
thanks to Keith Busch for working on, and pushing for, these changes.
- A few other small fixes and cleanups across other DM targets.
* tag 'dm-3.20-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm: inherit QUEUE_FLAG_SG_GAPS flags from underlying queues
dm snapshot: remove unnecessary NULL checks before vfree() calls
dm mpath: simplify failure path of dm_multipath_init()
dm thin metadata: remove unused dm_pool_get_data_block_size()
dm ioctl: fix stale comment above dm_get_inactive_table()
dm crypt: update url in CONFIG_DM_CRYPT help text
dm bufio: fix time comparison to use time_after_eq()
dm: use time_in_range() and time_after()
dm raid: fix a couple integer overflows
dm table: train hybrid target type detection to select blk-mq if appropriate
dm: allocate requests in target when stacking on blk-mq devices
dm: prepare for allocating blk-mq clone requests in target
dm: submit stacked requests in irq enabled context
dm: split request structure out from dm_rq_target_io structure
dm: remove exports for request-based interfaces without external callers
