linux.git/mm/filemap.c, branch v5.19

filemap: Handle sibling entries in filemap_get_read_batch()

2022-06-20T20:37:45+00:00

If a read races with an invalidation followed by another read, it is
possible for a folio to be replaced with a higher-order folio.  If that
happens, we'll see a sibling entry for the new folio in the next iteration
of the loop.  This manifests as a NULL pointer dereference while holding
the RCU read lock.

Handle this by simply returning.  The next call will find the new folio
and handle it correctly.  The other ways of handling this rare race are
more complex and it's just not worth it.

Reported-by: Dave Chinner 
Reported-by: Brian Foster 
Debugged-by: Brian Foster 
Tested-by: Brian Foster 
Reviewed-by: Brian Foster 
Fixes: cbd59c48ae2b ("mm/filemap: use head pages in generic_file_buffered_read")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle)

filemap: Correct the conditions for marking a folio as accessed

2022-06-20T20:37:45+00:00

We had an off-by-one error which meant that we never marked the first page
in a read as accessed.  This was visible as a slowdown when re-reading
a file as pages were being evicted from cache too soon.  In reviewing
this code, we noticed a second bug where a multi-page folio would be
marked as accessed multiple times when doing reads that were less than
the size of the folio.

Abstract the comparison of whether two file positions are in the same
folio into a new function, fixing both of these bugs.

Reported-by: Yu Kuai 
Reviewed-by: Kent Overstreet 
Signed-off-by: Matthew Wilcox (Oracle)

filemap: Cache the value of vm_flags

2022-06-09T20:24:25+00:00

After we have unlocked the mmap_lock for I/O, the file is pinned, but
the VMA is not.  Checking this flag after that can be a use-after-free.
It's not a terribly interesting use-after-free as it can only read one
bit, and it's used to decide whether to read 2MB or 4MB.  But it
upsets the automated tools and it's generally bad practice anyway,
so let's fix it.

Reported-by: syzbot+5b96d55e5b54924c77ad@syzkaller.appspotmail.com
Fixes: 4687fdbb805a ("mm/filemap: Support VM_HUGEPAGE for file mappings")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle)

Merge tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-05-26T19:32:41+00:00

Pull MM updates from Andrew Morton:
"Almost all of MM here. A few things are still getting finished off,
reviewed, etc.

- Yang Shi has improved the behaviour of khugepaged collapsing of
readonly file-backed transparent hugepages.

- Johannes Weiner has arranged for zswap memory use to be tracked and
managed on a per-cgroup basis.

- Munchun Song adds a /proc knob ("hugetlb_optimize_vmemmap") for
runtime enablement of the recent huge page vmemmap optimization
feature.

- Baolin Wang contributes a series to fix some issues around hugetlb
pagetable invalidation.

- Zhenwei Pi has fixed some interactions between hwpoisoned pages and
virtualization.

- Tong Tiangen has enabled the use of the presently x86-only
page_table_check debugging feature on arm64 and riscv.

- David Vernet has done some fixup work on the memcg selftests.

- Peter Xu has taught userfaultfd to handle write protection faults
against shmem- and hugetlbfs-backed files.

- More DAMON development from SeongJae Park - adding online tuning of
the feature and support for monitoring of fixed virtual address
ranges. Also easier discovery of which monitoring operations are
available.

- Nadav Amit has done some optimization of TLB flushing during
mprotect().

- Neil Brown continues to labor away at improving our swap-over-NFS
support.

- David Hildenbrand has some fixes to anon page COWing versus
get_user_pages().

- Peng Liu fixed some errors in the core hugetlb code.

- Joao Martins has reduced the amount of memory consumed by
device-dax's compound devmaps.

- Some cleanups of the arch-specific pagemap code from Anshuman
Khandual.

- Muchun Song has found and fixed some errors in the TLB flushing of
transparent hugepages.

- Roman Gushchin has done more work on the memcg selftests.

... and, of course, many smaller fixes and cleanups. Notably, the
customary million cleanup serieses from Miaohe Lin"

* tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (381 commits)
mm: kfence: use PAGE_ALIGNED helper
selftests: vm: add the "settings" file with timeout variable
selftests: vm: add "test_hmm.sh" to TEST_FILES
selftests: vm: check numa_available() before operating "merge_across_nodes" in ksm_tests
selftests: vm: add migration to the .gitignore
selftests/vm/pkeys: fix typo in comment
ksm: fix typo in comment
selftests: vm: add process_mrelease tests
Revert "mm/vmscan: never demote for memcg reclaim"
mm/kfence: print disabling or re-enabling message
include/trace/events/percpu.h: cleanup for "percpu: improve percpu_alloc_percpu event trace"
include/trace/events/mmflags.h: cleanup for "tracing: incorrect gfp_t conversion"
mm: fix a potential infinite loop in start_isolate_page_range()
MAINTAINERS: add Muchun as co-maintainer for HugeTLB
zram: fix Kconfig dependency warning
mm/shmem: fix shmem folio swapoff hang
cgroup: fix an error handling path in alloc_pagecache_max_30M()
mm: damon: use HPAGE_PMD_SIZE
tracing: incorrect isolate_mote_t cast in mm_vmscan_lru_isolate
nodemask.h: fix compilation error with GCC12
...

mm: teach core mm about pte markers

2022-05-13T14:20:09+00:00

This patch still does not use pte marker in any way, however it teaches
the core mm about the pte marker idea.

For example, handle_pte_marker() is introduced that will parse and handle
all the pte marker faults.

Many of the places are more about commenting it up - so that we know
there's the possibility of pte marker showing up, and why we don't need
special code for the cases.

[peterx@redhat.com: userfaultfd.c needs swapops.h]
  Link: https://lkml.kernel.org/r/YmRlVj3cdizYJsr0@xz-m1.local
Link: https://lkml.kernel.org/r/20220405014833.14015-1-peterx@redhat.com
Signed-off-by: Peter Xu 
Cc: Alistair Popple 
Cc: Andrea Arcangeli 
Cc: Axel Rasmussen 
Cc: David Hildenbrand 
Cc: Hugh Dickins 
Cc: Jerome Glisse 
Cc: "Kirill A . Shutemov" 
Cc: Matthew Wilcox 
Cc: Mike Kravetz 
Cc: Mike Rapoport 
Cc: Nadav Amit 
Signed-off-by: Andrew Morton

fs: Remove aops->freepage

2022-05-10T03:12:54+00:00

All implementations now use free_folio so we can delete the callers
and the method.

Signed-off-by: Matthew Wilcox (Oracle)

fs: Add free_folio address space operation

2022-05-10T03:12:52+00:00

Include documentation and convert the callers to use ->free_folio as
well as ->freepage.

Signed-off-by: Matthew Wilcox (Oracle)

fs: Change try_to_free_buffers() to take a folio

2022-05-10T03:12:34+00:00

All but two of the callers already have a folio; pass a folio into
try_to_free_buffers().  This removes the last user of cancel_dirty_page()
so remove that wrapper function too.

Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Jeff Layton

fs: Remove last vestiges of releasepage

2022-05-10T03:12:33+00:00

All users are now converted to release_folio

Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Jeff Layton

fs: Add aops->release_folio

2022-05-10T03:12:30+00:00

This replaces aops->releasepage.  Update the documentation, and call it
if it exists.

Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Jeff Layton