Let's clean up do_wp_page() a bit, removing two labels and making it a
easier to read.
wp_can_reuse_anon_folio() now only operates on the whole folio. Move the
SetPageAnonExclusive() out into do_wp_page(). No need to do this under
page lock -- the page table lock is sufficient.
Link: https://lkml.kernel.org/r/20231002142949.235104-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()".
Convert page_move_anon_rmap() to folio_move_anon_rmap(), letting the
callers handle PageAnonExclusive. I'm including cleanup patch #3 because
it fits into the picture and can be done cleaner by the conversion.
This patch (of 3):
Let's move it into the caller: there is a difference between whether an
anon folio can only be mapped by one process (e.g., into one VMA), and
whether it is truly exclusive (e.g., no references -- including GUP --
from other processes).
Further, for large folios the page might not actually be pointing at the
head page of the folio, so it better be handled in the caller. This is a
preparation for converting page_move_anon_rmap() to consume a folio.
Link: https://lkml.kernel.org/r/20231002142949.235104-1-david@redhat.com
Link: https://lkml.kernel.org/r/20231002142949.235104-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
I think this is a pretty rare occurrence, but for consistency handle
faults with the VMA lock held the same way that we handle other faults
with the VMA lock held.
Link: https://lkml.kernel.org/r/20231006195318.4087158-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Most file-backed faults are already handled through ->map_pages(), but if
we need to do I/O we'll come this way. Since filemap_fault() is now safe
to be called under the VMA lock, we can handle these faults under the VMA
lock now.
Link: https://lkml.kernel.org/r/20231006195318.4087158-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If the page is not currently present in the page tables, we need to call
the page fault handler to find out which page we're supposed to COW, so we
need to both check that there is already an anon_vma and that the fault
handler doesn't need the mmap_lock.
Link: https://lkml.kernel.org/r/20231006195318.4087158-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There are many implementations of ->fault and some of them depend on
mmap_lock being held. All vm_ops that implement ->map_pages() end up
calling filemap_fault(), which I have audited to be sure it does not rely
on mmap_lock. So (for now) key off ->map_pages existing as a flag to
indicate that it's safe to call ->fault while only holding the vma lock.
Link: https://lkml.kernel.org/r/20231006195318.4087158-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
It is usually safe to call wp_page_copy() under the VMA lock. The only
unsafe situation is when no anon_vma has been allocated for this VMA, and
we have to look at adjacent VMAs to determine if their anon_vma can be
shared. Since this happens only for the first COW of a page in this VMA,
the majority of calls to wp_page_copy() do not need to fall back to the
mmap_sem.
Add vmf_anon_prepare() as an alternative to anon_vma_prepare() which will
return RETRY if we currently hold the VMA lock and need to allocate an
anon_vma. This lets us drop the check in do_wp_page().
Link: https://lkml.kernel.org/r/20231006195318.4087158-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Handle more faults under the VMA lock", v2.
At this point, we're handling the majority of file-backed page faults
under the VMA lock, using the ->map_pages entry point. This patch set
attempts to expand that for the following siutations:
- We have to do a read. This could be because we've hit the point in
the readahead window where we need to kick off the next readahead,
or because the page is simply not present in cache.
- We're handling a write fault. Most applications don't do I/O by writes
to shared mmaps for very good reasons, but some do, and it'd be nice
to not make that slow unnecessarily.
- We're doing a COW of a private mapping (both PTE already present
and PTE not-present). These are two different codepaths and I handle
both of them in this patch set.
There is no support in this patch set for drivers to mark themselves as
being VMA lock friendly; they could implement the ->map_pages
vm_operation, but if they do, they would be the first. This is probably
something we want to change at some point in the future, and I've marked
where to make that change in the code.
There is very little performance change in the benchmarks we've run;
mostly because the vast majority of page faults are handled through the
other paths. I still think this patch series is useful for workloads that
may take these paths more often, and just for cleaning up the fault path
in general (it's now clearer why we have to retry in these cases).
This patch (of 6):
Drop the VMA lock instead of the mmap_lock if that's the one which
is held.
Link: https://lkml.kernel.org/r/20231006195318.4087158-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231006195318.4087158-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Percpu counter's compare and add are separate functions: without locking
around them (which would defeat their purpose), it has been possible to
overflow the intended limit. Imagine all the other CPUs fallocating tmpfs
huge pages to the limit, in between this CPU's compare and its add.
I have not seen reports of that happening; but tmpfs's recent addition of
dquot_alloc_block_nodirty() in between the compare and the add makes it
even more likely, and I'd be uncomfortable to leave it unfixed.
Introduce percpu_counter_limited_add(fbc, limit, amount) to prevent it.
I believe this implementation is correct, and slightly more efficient than
the combination of compare and add (taking the lock once rather than twice
when nearing full - the last 128MiB of a tmpfs volume on a machine with
128 CPUs and 4KiB pages); but it does beg for a better design - when
nearing full, there is no new batching, but the costly percpu counter sum
across CPUs still has to be done, while locked.
Follow __percpu_counter_sum()'s example, including cpu_dying_mask as well
as cpu_online_mask: but shouldn't __percpu_counter_compare() and
__percpu_counter_limited_add() then be adding a num_dying_cpus() to
num_online_cpus(), when they calculate the maximum which could be held
across CPUs? But the times when it matters would be vanishingly rare.
Link: https://lkml.kernel.org/r/bb817848-2d19-bcc8-39ca-ea179af0f0b4@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There has been a recurring problem, that when a tmpfs volume is being
filled by racing threads, some fail with ENOSPC (or consequent SIGBUS or
EFAULT) even though all allocations were within the permitted size.
This was a problem since early days, but magnified and complicated by the
addition of huge pages. We have often worked around it by adding some
slop to the tmpfs size, but it's hard to say how much is needed, and some
users prefer not to do that e.g. keeping sparse files in a tightly
tailored tmpfs helps to prevent accidental writing to holes.
This comes from the allocation sequence:
1. check page cache for existing folio
2. check and reserve from vm_enough_memory
3. check and account from size of tmpfs
4. if huge, check page cache for overlapping folio
5. allocate physical folio, huge or small
6. check and charge from mem cgroup limit
7. add to page cache (but maybe another folio already got in).
Concurrent tasks allocating at the same position could deplete the size
allowance and fail. Doing vm_enough_memory and size checks before the
folio allocation was intentional (to limit the load on the page allocator
from this source) and still has some virtue; but memory cgroup never did
that, so I think it's better reordered to favour predictable behaviour.
1. check page cache for existing folio
2. if huge, check page cache for overlapping folio
3. allocate physical folio, huge or small
4. check and charge from mem cgroup limit
5. add to page cache (but maybe another folio already got in)
6. check and reserve from vm_enough_memory
7. check and account from size of tmpfs.
The folio lock held from allocation onwards ensures that the !uptodate
folio cannot be used by others, and can safely be deleted from the cache
if checks 6 or 7 subsequently fail (and those waiting on folio lock
already check that the folio was not truncated once they get the lock);
and the early addition to page cache ensures that racers find it before
they try to duplicate the accounting.
Seize the opportunity to tidy up shmem_get_folio_gfp()'s ENOSPC retrying,
which can be combined inside the new shmem_alloc_and_add_folio(): doing 2
splits twice (once huge, once nonhuge) is not exactly equivalent to trying
5 splits (and giving up early on huge), but let's keep it simple unless
more complication proves necessary.
Userfaultfd is a foreign country: they do things differently there, and
for good reason - to avoid mmap_lock deadlock. Leave ordering in
shmem_mfill_atomic_pte() untouched for now, but I would rather like to
mesh it better with shmem_get_folio_gfp() in the future.
Link: https://lkml.kernel.org/r/22ddd06-d919-33b-1219-56335c1bf28e@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Extract shmem's memcg charging out of shmem_add_to_page_cache(): it's
misleading done there, because many calls are dealing with a swapcache
page, whose memcg is nowadays always remembered while swapped out, then
the charge re-levied when it's brought back into swapcache.
Temporarily move it back up to the shmem_get_folio_gfp() level, where the
memcg was charged before v5.8; but the next commit goes on to move it back
down to a new home.
In making this change, it becomes clear that shmem_swapin_folio() does not
need to know the vma, just the fault mm (if any): call it fault_mm rather
than charge_mm - let mem_cgroup_charge() decide whom to charge.
Link: https://lkml.kernel.org/r/4b2143c5-bf32-64f0-841-81a81158dac@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
By historical accident, shmem_acct_block() and shmem_inode_acct_block()
were never pluralized when the pages argument was added, despite their
complements being shmem_unacct_blocks() and shmem_inode_unacct_blocks()
all along. It has been an irritation: fix their naming at last.
Link: https://lkml.kernel.org/r/9124094-e4ab-8be7-ef80-9a87bdc2e4fc@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mostly removing a few superfluous blank lines, joining short arglines,
imposing some 80-column observance, correcting a couple of comments. None
of it more interesting than deleting a repeated INIT_LIST_HEAD().
Link: https://lkml.kernel.org/r/b3983d28-5d3f-8649-36af-b819285d7a9e@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
That Trinity livelock shmem_falloc avoidance block is unlikely, and a
distraction from the proper business of shmem_fault(): separate it out.
(This used to help compilers save stack on the fault path too, but both
gcc and clang nowadays seem to make better choices anyway.)
Link: https://lkml.kernel.org/r/6fe379a4-6176-9225-9263-fe60d2633c0@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The vma is already there in vmf->vma, so no need for a separate arg.
Link: https://lkml.kernel.org/r/d9ce6f65-a2ed-48f4-4299-fdb0544875c5@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The existing comments in filemap_fault() suggest that, after either a
minor fault has occurred and filemap_get_folio() found a folio in the page
cache, or a major fault arose and __filemap_get_folio(FGP_CREATE...) did
the job (having relied on do_sync_mmap_readahead() or filemap_read_folio()
to read in the folio), the only possible reason it could not be uptodate
is because of an error.
This is not so, as if, for instance, the fault occurred within a VMA which
had the VM_RAND_READ flag set (via madvise() with the MADV_RANDOM flag
specified), this would cause even synchronous readahead to fail to read in
the folio.
I confirmed this by dropping page caches and faulting in memory
madvise()'d this way, observing that this code path was reached on each
occasion.
Clarify the comments to include this case, and additionally update the
comment recently added around the invalidate lock logic to make it clear
the comment explicitly refers to the minor fault case.
In addition, while we're here, refer to folios rather than pages.
[lstoakes@gmail.com: correct identation as per Christopher's feedback]
Link: https://lkml.kernel.org/r/2c7014c0-6343-4e76-8697-3f84f54350bd@lucifer.local
Link: https://lkml.kernel.org/r/20230930231029.88196-1-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The PAGEMAP_SCAN IOCTL on the pagemap file can be used to get or optionally
clear the info about page table entries. The following operations are
supported in this IOCTL:
- Scan the address range and get the memory ranges matching the provided
criteria. This is performed when the output buffer is specified.
- Write-protect the pages. The PM_SCAN_WP_MATCHING is used to write-protect
the pages of interest. The PM_SCAN_CHECK_WPASYNC aborts the operation if
non-Async Write Protected pages are found. The ``PM_SCAN_WP_MATCHING``
can be used with or without PM_SCAN_CHECK_WPASYNC.
- Both of those operations can be combined into one atomic operation where
we can get and write protect the pages as well.
Following flags about pages are currently supported:
- PAGE_IS_WPALLOWED - Page has async-write-protection enabled
- PAGE_IS_WRITTEN - Page has been written to from the time it was write protected
- PAGE_IS_FILE - Page is file backed
- PAGE_IS_PRESENT - Page is present in the memory
- PAGE_IS_SWAPPED - Page is in swapped
- PAGE_IS_PFNZERO - Page has zero PFN
- PAGE_IS_HUGE - Page is THP or Hugetlb backed
This IOCTL can be extended to get information about more PTE bits. The
entire address range passed by user [start, end) is scanned until either
the user provided buffer is full or max_pages have been found.
[akpm@linux-foundation.org: update it for "mm: hugetlb: add huge page size param to set_huge_pte_at()"]
[akpm@linux-foundation.org: fix CONFIG_HUGETLB_PAGE=n warning]
[arnd@arndb.de: hide unused pagemap_scan_backout_range() function]
Link: https://lkml.kernel.org/r/20230927060257.2975412-1-arnd@kernel.org
[sfr@canb.auug.org.au: fix "fs/proc/task_mmu: hide unused pagemap_scan_backout_range() function"]
Link: https://lkml.kernel.org/r/20230928092223.0625c6bf@canb.auug.org.au
Link: https://lkml.kernel.org/r/20230821141518.870589-3-usama.anjum@collabora.com
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Miroslaw <emmir@google.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Paul Gofman <pgofman@codeweavers.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yun Zhou <yun.zhou@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Implement IOCTL to get and optionally clear info about
PTEs", v33.
*Motivation*
The real motivation for adding PAGEMAP_SCAN IOCTL is to emulate Windows
GetWriteWatch() and ResetWriteWatch() syscalls [1]. The GetWriteWatch()
retrieves the addresses of the pages that are written to in a region of
virtual memory.
This syscall is used in Windows applications and games etc. This syscall
is being emulated in pretty slow manner in userspace. Our purpose is to
enhance the kernel such that we translate it efficiently in a better way.
Currently some out of tree hack patches are being used to efficiently
emulate it in some kernels. We intend to replace those with these
patches. So the whole gaming on Linux can effectively get benefit from
this. It means there would be tons of users of this code.
CRIU use case [2] was mentioned by Andrei and Danylo:
> Use cases for migrating sparse VMAs are binaries sanitized with ASAN,
> MSAN or TSAN [3]. All of these sanitizers produce sparse mappings of
> shadow memory [4]. Being able to migrate such binaries allows to highly
> reduce the amount of work needed to identify and fix post-migration
> crashes, which happen constantly.
Andrei defines the following uses of this code:
* it is more granular and allows us to track changed pages more
effectively. The current interface can clear dirty bits for the entire
process only. In addition, reading info about pages is a separate
operation. It means we must freeze the process to read information
about all its pages, reset dirty bits, only then we can start dumping
pages. The information about pages becomes more and more outdated,
while we are processing pages. The new interface solves both these
downsides. First, it allows us to read pte bits and clear the
soft-dirty bit atomically. It means that CRIU will not need to freeze
processes to pre-dump their memory. Second, it clears soft-dirty bits
for a specified region of memory. It means CRIU will have actual info
about pages to the moment of dumping them.
* The new interface has to be much faster because basic page filtering
is happening in the kernel. With the old interface, we have to read
pagemap for each page.
*Implementation Evolution (Short Summary)*
From the definition of GetWriteWatch(), we feel like kernel's soft-dirty
feature can be used under the hood with some additions like:
* reset soft-dirty flag for only a specific region of memory instead of
clearing the flag for the entire process
* get and clear soft-dirty flag for a specific region atomically
So we decided to use ioctl on pagemap file to read or/and reset soft-dirty
flag. But using soft-dirty flag, sometimes we get extra pages which weren't
even written. They had become soft-dirty because of VMA merging and
VM_SOFTDIRTY flag. This breaks the definition of GetWriteWatch(). We were
able to by-pass this short coming by ignoring VM_SOFTDIRTY until David
reported that mprotect etc messes up the soft-dirty flag while ignoring
VM_SOFTDIRTY [5]. This wasn't happening until [6] got introduced. We
discussed if we can revert these patches. But we could not reach to any
conclusion. So at this point, I made couple of tries to solve this whole
VM_SOFTDIRTY issue by correcting the soft-dirty implementation:
* [7] Correct the bug fixed wrongly back in 2014. It had potential to cause
regression. We left it behind.
* [8] Keep a list of soft-dirty part of a VMA across splits and merges. I
got the reply don't increase the size of the VMA by 8 bytes.
At this point, we left soft-dirty considering it is too much delicate and
userfaultfd [9] seemed like the only way forward. From there onward, we
have been basing soft-dirty emulation on userfaultfd wp feature where
kernel resolves the faults itself when WP_ASYNC feature is used. It was
straight forward to add WP_ASYNC feature in userfautlfd. Now we get only
those pages dirty or written-to which are really written in reality. (PS
There is another WP_UNPOPULATED userfautfd feature is required which is
needed to avoid pre-faulting memory before write-protecting [9].)
All the different masks were added on the request of CRIU devs to create
interface more generic and better.
[1] https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-getwritewatch
[2] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com
[3] https://github.com/google/sanitizers
[4] https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm#64-bit
[5] https://lore.kernel.org/all/bfcae708-db21-04b4-0bbe-712badd03071@redhat.com
[6] https://lore.kernel.org/all/20220725142048.30450-1-peterx@redhat.com/
[7] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.com
[8] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.com
[9] https://lore.kernel.org/all/20230306213925.617814-1-peterx@redhat.com
[10] https://lore.kernel.org/all/20230125144529.1630917-1-mdanylo@google.com
This patch (of 6):
Add a new userfaultfd-wp feature UFFD_FEATURE_WP_ASYNC, that allows
userfaultfd wr-protect faults to be resolved by the kernel directly.
It can be used like a high accuracy version of soft-dirty, without vma
modifications during tracking, and also with ranged support by default
rather than for a whole mm when reset the protections due to existence of
ioctl(UFFDIO_WRITEPROTECT).
Several goals of such a dirty tracking interface:
1. All types of memory should be supported and tracable. This is nature
for soft-dirty but should mention when the context is userfaultfd,
because it used to only support anon/shmem/hugetlb. The problem is for
a dirty tracking purpose these three types may not be enough, and it's
legal to track anything e.g. any page cache writes from mmap.
2. Protections can be applied to partial of a memory range, without vma
split/merge fuss. The hope is that the tracking itself should not
affect any vma layout change. It also helps when reset happens because
the reset will not need mmap write lock which can block the tracee.
3. Accuracy needs to be maintained. This means we need pte markers to work
on any type of VMA.
One could question that, the whole concept of async dirty tracking is not
really close to fundamentally what userfaultfd used to be: it's not "a
fault to be serviced by userspace" anymore. However, using userfaultfd-wp
here as a framework is convenient for us in at least:
1. VM_UFFD_WP vma flag, which has a very good name to suite something like
this, so we don't need VM_YET_ANOTHER_SOFT_DIRTY. Just use a new
feature bit to identify from a sync version of uffd-wp registration.
2. PTE markers logic can be leveraged across the whole kernel to maintain
the uffd-wp bit as long as an arch supports, this also applies to this
case where uffd-wp bit will be a hint to dirty information and it will
not go lost easily (e.g. when some page cache ptes got zapped).
3. Reuse ioctl(UFFDIO_WRITEPROTECT) interface for either starting or
resetting a range of memory, while there's no counterpart in the old
soft-dirty world, hence if this is wanted in a new design we'll need a
new interface otherwise.
We can somehow understand that commonality because uffd-wp was
fundamentally a similar idea of write-protecting pages just like
soft-dirty.
This implementation allows WP_ASYNC to imply WP_UNPOPULATED, because so
far WP_ASYNC seems to not usable if without WP_UNPOPULATE. This also
gives us chance to modify impl of WP_ASYNC just in case it could be not
depending on WP_UNPOPULATED anymore in the future kernels. It's also fine
to imply that because both features will rely on PTE_MARKER_UFFD_WP config
option, so they'll show up together (or both missing) in an UFFDIO_API
probe.
vma_can_userfault() now allows any VMA if the userfaultfd registration is
only about async uffd-wp. So we can track dirty for all kinds of memory
including generic file systems (like XFS, EXT4 or BTRFS).
One trick worth mention in do_wp_page() is that we need to manually update
vmf->orig_pte here because it can be used later with a pte_same() check -
this path always has FAULT_FLAG_ORIG_PTE_VALID set in the flags.
The major defect of this approach of dirty tracking is we need to populate
the pgtables when tracking starts. Soft-dirty doesn't do it like that.
It's unwanted in the case where the range of memory to track is huge and
unpopulated (e.g., tracking updates on a 10G file with mmap() on top,
without having any page cache installed yet). One way to improve this is
to allow pte markers exist for larger than PTE level for PMD+. That will
not change the interface if to implemented, so we can leave that for
later.
Link: https://lkml.kernel.org/r/20230821141518.870589-1-usama.anjum@collabora.com
Link: https://lkml.kernel.org/r/20230821141518.870589-2-usama.anjum@collabora.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Co-developed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Miroslaw <emmir@google.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Paul Gofman <pgofman@codeweavers.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yun Zhou <yun.zhou@windriver.com>
Cc: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
memcg_rstat_updated() uses the value of the state update to keep track of
the magnitude of pending updates, so that we only do a stats flush when
it's worth the work. Most values passed into memcg_rstat_updated() are in
pages, however, a few of them are actually in bytes or KBs.
To put this into perspective, a 512 byte slab allocation today would look
the same as allocating 512 pages. This may result in premature flushes,
which means unnecessary work and latency.
Normalize all the state values passed into memcg_rstat_updated() to pages.
Round up non-zero sub-page to 1 page, because memcg_rstat_updated()
ignores 0 page updates.
Link: https://lkml.kernel.org/r/20230922175741.635002-3-yosryahmed@google.com
Fixes: 5b3be698a8 ("memcg: better bounds on the memcg stats updates")
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: memcg: fix tracking of pending stats updates values", v2.
While working on adjacent code [1], I realized that the values passed into
memcg_rstat_updated() to keep track of the magnitude of pending updates is
consistent. It is mostly in pages, but sometimes it can be in bytes or
KBs. Fix that.
Patch 1 reworks memcg_page_state_unit() so that we can reuse it in patch 2
to check and normalize the units of state updates.
[1]https://lore.kernel.org/lkml/20230921081057.3440885-1-yosryahmed@google.com/
This patch (of 2):
memcg_page_state_unit() is currently used to identify the unit of a memcg
state item so that all stats in memory.stat are in bytes. However, it
lies about the units of WORKINGSET_* stats. These stats actually
represent pages, but we present them to userspace as a scalar number of
events. In retrospect, maybe those stats should have been memcg "events"
rather than memcg "state".
In preparation for using memcg_page_state_unit() for other purposes that
need to know the truthful units of different stat items, break it down
into two helpers:
- memcg_page_state_unit() retuns the actual unit of the item.
- memcg_page_state_output_unit() returns the unit used for output.
Use the latter instead of the former in memcg_page_state_output() and
lruvec_page_state_output(). While we are at it, let's show cgroup v1 some
love and add memcg_page_state_local_output() for consistency.
No functional change intended.
Link: https://lkml.kernel.org/r/20230922175741.635002-1-yosryahmed@google.com
Link: https://lkml.kernel.org/r/20230922175741.635002-2-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In commit d8f5f7e445 ("hugetlb: set hugetlb page flag before
optimizing vmemmap") checks were added to print a warning if
hugetlb_vmemmap_restore was called on a non-hugetlb page.
This was mostly due to ordering issues in the hugetlb page set up and tear
down sequencees. One place missed was the routine
dissolve_free_huge_page.
Naoya Horiguchi noted: "I saw that VM_WARN_ON_ONCE() in
hugetlb_vmemmap_restore is triggered when memory_failure() is called on a
free hugetlb page with vmemmap optimization disabled (the warning is not
triggered if vmemmap optimization is enabled). I think that we need check
folio_test_hugetlb() before dissolve_free_huge_page() calls
hugetlb_vmemmap_restore_folio()."
Perform the check as suggested by Naoya.
Link: https://lkml.kernel.org/r/20231017032140.GA3680@monkey
Fixes: d8f5f7e445 ("hugetlb: set hugetlb page flag before optimizing vmemmap")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Tested-by: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMON_SYSFS can receive DAMOS tried regions update request while kdamond
is already out of the main loop and before_terminate callback
(damon_sysfs_before_terminate() in this case) is not yet called. And
damon_sysfs_handle_cmd() can further be finished before the callback is
invoked. Then, damon_sysfs_before_terminate() unlocks damon_sysfs_lock,
which is not locked by anyone. This happens because the callback function
assumes damon_sysfs_cmd_request_callback() should be called before it.
Check if the assumption was true before doing the unlock, to avoid this
problem.
Link: https://lkml.kernel.org/r/20231007200432.3110-1-sj@kernel.org
Fixes: f1d13cacab ("mm/damon/sysfs: implement DAMOS tried regions update command")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.2.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On arm64, building with CONFIG_KASAN_HW_TAGS now causes a compile-time
error:
mm/kasan/report.c: In function 'kasan_non_canonical_hook':
mm/kasan/report.c:637:20: error: 'KASAN_SHADOW_OFFSET' undeclared (first use in this function)
637 | if (addr < KASAN_SHADOW_OFFSET)
| ^~~~~~~~~~~~~~~~~~~
mm/kasan/report.c:637:20: note: each undeclared identifier is reported only once for each function it appears in
mm/kasan/report.c:640:77: error: expected expression before ';' token
640 | orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
This was caused by removing the dependency on CONFIG_KASAN_INLINE that
used to prevent this from happening. Use the more specific dependency
on KASAN_SW_TAGS || KASAN_GENERIC to only ignore the function for hwasan
mode.
Link: https://lkml.kernel.org/r/20231016200925.984439-1-arnd@kernel.org
Fixes: 12ec6a919b0f ("kasan: print the original fault addr when access invalid shadow")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Haibo Li <haibo.li@mediatek.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
when the checked address is illegal,the corresponding shadow address from
kasan_mem_to_shadow may have no mapping in mmu table. Access such shadow
address causes kernel oops. Here is a sample about oops on arm64(VA
39bit) with KASAN_SW_TAGS and KASAN_OUTLINE on:
[ffffffb80aaaaaaa] pgd=000000005d3ce003, p4d=000000005d3ce003,
pud=000000005d3ce003, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 3 PID: 100 Comm: sh Not tainted 6.6.0-rc1-dirty #43
Hardware name: linux,dummy-virt (DT)
pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __hwasan_load8_noabort+0x5c/0x90
lr : do_ib_ob+0xf4/0x110
ffffffb80aaaaaaa is the shadow address for efffff80aaaaaaaa.
The problem is reading invalid shadow in kasan_check_range.
The generic kasan also has similar oops.
It only reports the shadow address which causes oops but not
the original address.
Commit 2f004eea0fc8("x86/kasan: Print original address on #GP")
introduce to kasan_non_canonical_hook but limit it to KASAN_INLINE.
This patch extends it to KASAN_OUTLINE mode.
Link: https://lkml.kernel.org/r/20231009073748.159228-1-haibo.li@mediatek.com
Fixes: 2f004eea0fc8("x86/kasan: Print original address on #GP")
Signed-off-by: Haibo Li <haibo.li@mediatek.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Haibo Li <haibo.li@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Malloc libraries, like jemalloc and tcalloc, take decisions on when to
call madvise independently from the code in the main application.
This sometimes results in the application page faulting on an address,
right after the malloc library has shot down the backing memory with
MADV_DONTNEED.
Usually this is harmless, because we always have some 4kB pages sitting
around to satisfy a page fault. However, with hugetlbfs systems often
allocate only the exact number of huge pages that the application wants.
Due to TLB batching, hugetlbfs MADV_DONTNEED will free pages outside of
any lock taken on the page fault path, which can open up the following
race condition:
CPU 1 CPU 2
MADV_DONTNEED
unmap page
shoot down TLB entry
page fault
fail to allocate a huge page
killed with SIGBUS
free page
Fix that race by pulling the locking from __unmap_hugepage_final_range
into helper functions called from zap_page_range_single. This ensures
page faults stay locked out of the MADV_DONTNEED VMA until the huge pages
have actually been freed.
Link: https://lkml.kernel.org/r/20231006040020.3677377-4-riel@surriel.com
Fixes: 04ada095dc ("hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing")
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Extend the locking scheme used to protect shared hugetlb mappings from
truncate vs page fault races, in order to protect private hugetlb mappings
(with resv_map) against MADV_DONTNEED.
Add a read-write semaphore to the resv_map data structure, and use that
from the hugetlb_vma_(un)lock_* functions, in preparation for closing the
race between MADV_DONTNEED and page faults.
Link: https://lkml.kernel.org/r/20231006040020.3677377-3-riel@surriel.com
Fixes: 04ada095dc ("hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing")
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "hugetlbfs: close race between MADV_DONTNEED and page fault", v7.
Malloc libraries, like jemalloc and tcalloc, take decisions on when to
call madvise independently from the code in the main application.
This sometimes results in the application page faulting on an address,
right after the malloc library has shot down the backing memory with
MADV_DONTNEED.
Usually this is harmless, because we always have some 4kB pages sitting
around to satisfy a page fault. However, with hugetlbfs systems often
allocate only the exact number of huge pages that the application wants.
Due to TLB batching, hugetlbfs MADV_DONTNEED will free pages outside of
any lock taken on the page fault path, which can open up the following
race condition:
CPU 1 CPU 2
MADV_DONTNEED
unmap page
shoot down TLB entry
page fault
fail to allocate a huge page
killed with SIGBUS
free page
Fix that race by extending the hugetlb_vma_lock locking scheme to also
cover private hugetlb mappings (with resv_map), and pulling the locking
from __unmap_hugepage_final_range into helper functions called from
zap_page_range_single. This ensures page faults stay locked out of the
MADV_DONTNEED VMA until the huge pages have actually been freed.
This patch (of 3):
Hugetlbfs leaves a dangling pointer in the VMA if mmap fails. This has
not been a problem so far, but other code in this patch series tries to
follow that pointer.
Link: https://lkml.kernel.org/r/20231006040020.3677377-1-riel@surriel.com
Link: https://lkml.kernel.org/r/20231006040020.3677377-2-riel@surriel.com
Fixes: 04ada095dc ("hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Rik van Riel <riel@surriel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When a zswap store fails due to the limit, it acquires a pool reference
and queues the shrinker. When the shrinker runs, it drops the reference.
However, there can be multiple store attempts before the shrinker wakes up
and runs once. This results in reference leaks and eventual saturation
warnings for the pool refcount.
Fix this by dropping the reference again when the shrinker is already
queued. This ensures one reference per shrinker run.
Link: https://lkml.kernel.org/r/20231006160024.170748-1-hannes@cmpxchg.org
Fixes: 45190f01dd ("mm/zswap.c: add allocation hysteresis if pool limit is hit")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Chris Mason <clm@fb.com>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: <stable@vger.kernel.org> [5.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This change adds the "pages skipped" metric. To be able to evaluate how
successful smart page scanning is, the pages skipped metric can be
compared to the pages scanned metric.
The pages skipped metric is a cumulative counter. The counter is stored
under /sys/kernel/mm/ksm/pages_skipped.
Link: https://lkml.kernel.org/r/20230926040939.516161-3-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Smart scanning mode for KSM", v3.
This patch series adds "smart scanning" for KSM.
What is smart scanning?
=======================
KSM evaluates all the candidate pages for each scan. It does not use historic
information from previous scans. This has the effect that candidate pages that
couldn't be used for KSM de-duplication continue to be evaluated for each scan.
The idea of "smart scanning" is to keep historic information. With the historic
information we can temporarily skip the candidate page for one or several scans.
Details:
========
"Smart scanning" is to keep two small counters to store if the page has been
used for KSM. One counter stores how often we already tried to use the page for
KSM and the other counter stores how often we skip a page.
How often we skip the candidate page depends how often a page failed KSM
de-duplication. The code skips a maximum of 8 times. During testing this has
shown to be a good compromise for different workloads.
New sysfs knob:
===============
Smart scanning is not enabled by default. With /sys/kernel/mm/ksm/smart_scan
smart scanning can be enabled.
Monitoring:
===========
To monitor how effective smart scanning is a new sysfs knob has been introduced.
/sys/kernel/mm/pages_skipped report how many pages have been skipped by smart
scanning.
Results:
========
- Various workloads have shown a 20% - 25% reduction in page scans
For the instagram workload for instance, the number of pages scanned has been
reduced from over 20M pages per scan to less than 15M pages.
- Less pages scans also resulted in an overall higher de-duplication rate as
some shorter lived pages could be de-duplicated additionally
- Less pages scanned allows to reduce the pages_to_scan parameter
and this resulted in a 25% reduction in terms of CPU.
- The improvements have been observed for workloads that enable KSM with
madvise as well as prctl
This patch (of 4):
This change adds a "smart" page scanning mode for KSM. So far all the
candidate pages are continuously scanned to find candidates for
de-duplication. There are a considerably number of pages that cannot be
de-duplicated. This is costly in terms of CPU. By using smart scanning
considerable CPU savings can be achieved.
This change takes the history of scanning pages into account and skips the
page scanning of certain pages for a while if de-deduplication for this
page has not been successful in the past.
To do this it introduces two new fields in the ksm_rmap_item structure:
age and remaining_skips. age, is the KSM age and remaining_skips
determines how often scanning of this page is skipped. The age field is
incremented each time the page is scanned and the page cannot be de-
duplicated. age updated is capped at U8_MAX.
How often a page is skipped is dependent how often de-duplication has been
tried so far and the number of skips is currently limited to 8. This
value has shown to be effective with different workloads.
The feature is currently disable by default and can be enabled with the
new smart_scan knob.
The feature has shown to be very effective: upt to 25% of the page scans
can be eliminated; the pages_to_scan rate can be reduced by 40 - 50% and a
similar de-duplication rate can be maintained.
[akpm@linux-foundation.org: make ksm_smart_scan default true, for testing]
Link: https://lkml.kernel.org/r/20230926040939.516161-1-shr@devkernel.io
Link: https://lkml.kernel.org/r/20230926040939.516161-2-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Stefan Roesch <shr@devkernel.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Previously, a fixed abstract distance MEMTIER_DEFAULT_DAX_ADISTANCE is
used for slow memory type in kmem driver. This limits the usage of kmem
driver, for example, it cannot be used for HBM (high bandwidth memory).
So, we use the general abstract distance calculation mechanism in kmem
drivers to get more accurate abstract distance on systems with proper
support. The original MEMTIER_DEFAULT_DAX_ADISTANCE is used as fallback
only.
Now, multiple memory types may be managed by kmem. These memory types are
put into the "kmem_memory_types" list and protected by
kmem_memory_type_lock.
Link: https://lkml.kernel.org/r/20230926060628.265989-5-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Bharata B Rao <bharata@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
A memory tiering abstract distance calculation algorithm based on ACPI
HMAT is implemented. The basic idea is as follows.
The performance attributes of system default DRAM nodes are recorded as
the base line. Whose abstract distance is MEMTIER_ADISTANCE_DRAM. Then,
the ratio of the abstract distance of a memory node (target) to
MEMTIER_ADISTANCE_DRAM is scaled based on the ratio of the performance
attributes of the node to that of the default DRAM nodes.
The functions to record the read/write latency/bandwidth of the default
DRAM nodes and calculate abstract distance according to read/write
latency/bandwidth ratio will be used by CXL CDAT (Coherent Device
Attribute Table) and other memory device drivers. So, they are put in
memory-tiers.c.
Link: https://lkml.kernel.org/r/20230926060628.265989-4-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Bharata B Rao <bharata@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "memory tiering: calculate abstract distance based on ACPI
HMAT", v4.
We have the explicit memory tiers framework to manage systems with
multiple types of memory, e.g., DRAM in DIMM slots and CXL memory devices.
Where, same kind of memory devices will be grouped into memory types,
then put into memory tiers. To describe the performance of a memory type,
abstract distance is defined. Which is in direct proportion to the memory
latency and inversely proportional to the memory bandwidth. To keep the
code as simple as possible, fixed abstract distance is used in dax/kmem to
describe slow memory such as Optane DCPMM.
To support more memory types, in this series, we added the abstract
distance calculation algorithm management mechanism, provided a algorithm
implementation based on ACPI HMAT, and used the general abstract distance
calculation interface in dax/kmem driver. So, dax/kmem can support HBM
(high bandwidth memory) in addition to the original Optane DCPMM.
This patch (of 4):
The abstract distance may be calculated by various drivers, such as ACPI
HMAT, CXL CDAT, etc. While it may be used by various code which hot-add
memory node, such as dax/kmem etc. To decouple the algorithm users and
the providers, the abstract distance calculation algorithms management
mechanism is implemented in this patch. It provides interface for the
providers to register the implementation, and interface for the users.
Multiple algorithm implementations can cooperate via calculating abstract
distance for different memory nodes. The preference of algorithm
implementations can be specified via priority (notifier_block.priority).
Link: https://lkml.kernel.org/r/20230926060628.265989-1-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20230926060628.265989-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Bharata B Rao <bharata@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
No functional difference, folio_ref_freeze() is currently a wrapper for
page_ref_freeze().
Link: https://lkml.kernel.org/r/20230926174433.81241-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Remove special cased hugetlb handling code within the page cache by
changing the granularity of ->index to the base page size rather than the
huge page size. The motivation of this patch is to reduce complexity
within the filemap code while also increasing performance by removing
branches that are evaluated on every page cache lookup.
To support the change in index, new wrappers for hugetlb page cache
interactions are added. These wrappers perform the conversion to a linear
index which is now expected by the page cache for huge pages.
========================= PERFORMANCE ======================================
Perf was used to check the performance differences after the patch.
Overall the performance is similar to mainline with a very small larger
overhead that occurs in __filemap_add_folio() and
hugetlb_add_to_page_cache(). This is because of the larger overhead that
occurs in xa_load() and xa_store() as the xarray is now using more entries
to store hugetlb folios in the page cache.
Timing
aarch64
2MB Page Size
6.5-rc3 + this patch:
[root@sidhakum-ol9-1 hugepages]# time fallocate -l 700GB test.txt
real 1m49.568s
user 0m0.000s
sys 1m49.461s
6.5-rc3:
[root]# time fallocate -l 700GB test.txt
real 1m47.495s
user 0m0.000s
sys 1m47.370s
1GB Page Size
6.5-rc3 + this patch:
[root@sidhakum-ol9-1 hugepages1G]# time fallocate -l 700GB test.txt
real 1m47.024s
user 0m0.000s
sys 1m46.921s
6.5-rc3:
[root@sidhakum-ol9-1 hugepages1G]# time fallocate -l 700GB test.txt
real 1m44.551s
user 0m0.000s
sys 1m44.438s
x86
2MB Page Size
6.5-rc3 + this patch:
[root@sidhakum-ol9-2 hugepages]# time fallocate -l 100GB test.txt
real 0m22.383s
user 0m0.000s
sys 0m22.255s
6.5-rc3:
[opc@sidhakum-ol9-2 hugepages]$ time sudo fallocate -l 100GB /dev/hugepages/test.txt
real 0m22.735s
user 0m0.038s
sys 0m22.567s
1GB Page Size
6.5-rc3 + this patch:
[root@sidhakum-ol9-2 hugepages1GB]# time fallocate -l 100GB test.txt
real 0m25.786s
user 0m0.001s
sys 0m25.589s
6.5-rc3:
[root@sidhakum-ol9-2 hugepages1G]# time fallocate -l 100GB test.txt
real 0m33.454s
user 0m0.001s
sys 0m33.193s
aarch64:
workload - fallocate a 700GB file backed by huge pages
6.5-rc3 + this patch:
2MB Page Size:
--100.00%--__arm64_sys_fallocate
ksys_fallocate
vfs_fallocate
hugetlbfs_fallocate
|
|--95.04%--__pi_clear_page
|
|--3.57%--clear_huge_page
| |
| |--2.63%--rcu_all_qs
| |
| --0.91%--__cond_resched
|
--0.67%--__cond_resched
0.17% 0.00% 0 fallocate [kernel.vmlinux] [k] hugetlb_add_to_page_cache
0.14% 0.10% 11 fallocate [kernel.vmlinux] [k] __filemap_add_folio
6.5-rc3
2MB Page Size:
--100.00%--__arm64_sys_fallocate
ksys_fallocate
vfs_fallocate
hugetlbfs_fallocate
|
|--94.91%--__pi_clear_page
|
|--4.11%--clear_huge_page
| |
| |--3.00%--rcu_all_qs
| |
| --1.10%--__cond_resched
|
--0.59%--__cond_resched
0.08% 0.01% 1 fallocate [kernel.kallsyms] [k] hugetlb_add_to_page_cache
0.05% 0.03% 3 fallocate [kernel.kallsyms] [k] __filemap_add_folio
x86
workload - fallocate a 100GB file backed by huge pages
6.5-rc3 + this patch:
2MB Page Size:
hugetlbfs_fallocate
|
--99.57%--clear_huge_page
|
--98.47%--clear_page_erms
|
--0.53%--asm_sysvec_apic_timer_interrupt
0.04% 0.04% 1 fallocate [kernel.kallsyms] [k] xa_load
0.04% 0.00% 0 fallocate [kernel.kallsyms] [k] hugetlb_add_to_page_cache
0.04% 0.00% 0 fallocate [kernel.kallsyms] [k] __filemap_add_folio
0.04% 0.00% 0 fallocate [kernel.kallsyms] [k] xas_store
6.5-rc3
2MB Page Size:
--99.93%--__x64_sys_fallocate
vfs_fallocate
hugetlbfs_fallocate
|
--99.38%--clear_huge_page
|
|--98.40%--clear_page_erms
|
--0.59%--__cond_resched
0.03% 0.03% 1 fallocate [kernel.kallsyms] [k] __filemap_add_folio
========================= TESTING ======================================
This patch passes libhugetlbfs tests and LTP hugetlb tests
********** TEST SUMMARY
* 2M
* 32-bit 64-bit
* Total testcases: 110 113
* Skipped: 0 0
* PASS: 107 113
* FAIL: 0 0
* Killed by signal: 3 0
* Bad configuration: 0 0
* Expected FAIL: 0 0
* Unexpected PASS: 0 0
* Test not present: 0 0
* Strange test result: 0 0
**********
Done executing testcases.
LTP Version: 20220527-178-g2761a81c4
page migration was also tested using Mike Kravetz's test program.[8]
[dan.carpenter@linaro.org: fix an NULL vs IS_ERR() bug]
Link: https://lkml.kernel.org/r/1772c296-1417-486f-8eef-171af2192681@moroto.mountain
Link: https://lkml.kernel.org/r/20230926192017.98183-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reported-and-tested-by: syzbot+c225dea486da4d5592bd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c225dea486da4d5592bd
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
si_meminfo() will read and assign more info not just free/ram pages. For
just DAMOS_WMARK_FREE_MEM_RATE use, only get free and ram pages is ok to
save cpu.
Link: https://lkml.kernel.org/r/20230920015727.4482-1-link@vivo.com
Signed-off-by: Huan Yang <link@vivo.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The cpupid (or access time) is stored in the head page for THP, so it is
safely to make should_numa_migrate_memory() and numa_hint_fault_latency()
to take a folio. This is in preparation for large folio numa balancing.
Link: https://lkml.kernel.org/r/20230921074417.24004-7-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In preparation for large folio numa balancing, make mpol_misplaced() to
take a folio, no functional change intended.
Link: https://lkml.kernel.org/r/20230921074417.24004-6-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In preparation for large folio numa balancing, make numa_migrate_prep() to
take a folio, no functional change intended.
Link: https://lkml.kernel.org/r/20230921074417.24004-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Numa balancing only try to migrate non-compound page in do_numa_page(),
use a folio in it to save several compound_head calls, note we use
folio_estimated_sharers(), it is enough to check the folio sharers since
only normal page is handled, if large folio numa balancing is supported, a
precise folio sharers check would be used, no functional change intended.
Link: https://lkml.kernel.org/r/20230921074417.24004-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use a folio in do_huge_pmd_numa_page(), reduce three page_folio() calls to
one, no functional change intended.
Link: https://lkml.kernel.org/r/20230921074417.24004-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: convert numa balancing functions to use a folio", v2.
do_numa_pages() only handles non-compound pages, and only PMD-mapped THPs
are handled in do_huge_pmd_numa_page(). But a large, PTE-mapped folio
will be supported so let's convert more numa balancing functions to
use/take a folio in preparation for that, no functional change intended
for now.
This patch (of 6):
The new vm_normal_folio_pmd() wrapper is similar to vm_normal_folio(),
which allow them to completely replace the struct page variables with
struct folio variables.
Link: https://lkml.kernel.org/r/20230921074417.24004-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20230921074417.24004-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Simplify code pattern of 'folio->index + folio_nr_pages(folio)' by using
the existing helper folio_next_index() in filemap_map_pages().
Link: https://lkml.kernel.org/r/20230921081535.3398-1-duminjie@vivo.com
Signed-off-by: Minjie Du <duminjie@vivo.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The current memory reclaim delay statistics only count the direct memory
reclaim of the task in do_try_to_free_pages(). In systems with NUMA open,
some tasks occasionally experience slower response times, but the total
count of reclaim does not increase, using ftrace can show that
node_reclaim has occurred.
The memory reclaim occurring in get_page_from_freelist() is also due to
heavy memory load. To get the impact of tasks in memory reclaim, this
patch adds the statistics of the memory reclaim delay statistics for
__node_reclaim().
Link: https://lkml.kernel.org/r/181C946095F0252B+7cc60eca-1abf-4502-aad3-ffd8ef89d910@ex.bilibili.com
Signed-off-by: Wen Yu Li <wenyuli@ex.bilibili.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: <wangyun@bilibili.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since commit b25806dcd3d5("mm: memcontrol: deprecate swapaccounting=0
mode") do_memsw_account() is synonymous with
!cgroup_subsys_on_dfl(memory_cgrp_subsys), It always equals true in
memcg1_stat_format(). Remove the unused code.
Link: https://lkml.kernel.org/r/20230915105845.3199656-3-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Tejun heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Expose swapcache stat for memcg v1", v2.
Since commit b603894248 ("mm: memcg: add swapcache stat for memcg v2")
adds swapcache stat for the cgroup v2, it seems there is no reason to hide
it in memcg v1. Conversely, with swapcached it is more accurate to
evaluate the available memory for memcg.
Link: https://lkml.kernel.org/r/20230915105845.3199656-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20230915105845.3199656-2-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Suggested-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
First found this typo as reviewing memory tier code. Fix it by sed like:
$ sed -i 's/sibiling/sibling/g' $(git grep -l sibiling)
so the acpi one will be corrected as well.
Link: https://lkml.kernel.org/r/20230802092856.819328-1-lizhijian@cn.fujitsu.com
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
do_pages_move does not handle compat pointers for the page list.
correctly. Add in_compat_syscall check and appropriate get_user fetch
when iterating the page list.
It makes the syscall in compat mode (32-bit userspace, 64-bit kernel)
work the same way as the native 32-bit syscall again, restoring the
behavior before my broken commit 5b1b561ba7 ("mm: simplify
compat_sys_move_pages").
More specifically, my patch moved the parsing of the 'pages' array from
the main entry point into do_pages_stat(), which left the syscall
working correctly for the 'stat' operation (nodes = NULL), while the
'move' operation (nodes != NULL) is now missing the conversion and
interprets 'pages' as an array of 64-bit pointers instead of the
intended 32-bit userspace pointers.
It is possible that nobody noticed this bug because the few
applications that actually call move_pages are unlikely to run in
compat mode because of their large memory requirements, but this
clearly fixes a user-visible regression and should have been caught by
ltp.
Link: https://lkml.kernel.org/r/20231003144857.752952-1-gregory.price@memverge.com
Fixes: 5b1b561ba7 ("mm: simplify compat_sys_move_pages")
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
