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  1. 17 12月, 2021 2 次提交
  3. 25 11月, 2021 1 次提交
  5. 22 11月, 2021 1 次提交
    • A
      iomap: Fix inline extent handling in iomap_readpage · d8af404f
      由 Andreas Gruenbacher 提交于 
      Before commit 740499c7 ("iomap: fix the iomap_readpage_actor return
value for inline data"), when hitting an IOMAP_INLINE extent,
iomap_readpage_actor would report having read the entire page.  Since
then, it only reports having read the inline data (iomap->length).

This will force iomap_readpage into another iteration, and the
filesystem will report an unaligned hole after the IOMAP_INLINE extent.
But iomap_readpage_actor (now iomap_readpage_iter) isn't prepared to
deal with unaligned extents, it will get things wrong on filesystems
with a block size smaller than the page size, and we'll eventually run
into the following warning in iomap_iter_advance:

  WARN_ON_ONCE(iter->processed > iomap_length(iter));

Fix that by changing iomap_readpage_iter to return 0 when hitting an
inline extent; this will cause iomap_iter to stop immediately.

To fix readahead as well, change iomap_readahead_iter to pass on
iomap_readpage_iter return values less than or equal to zero.

Fixes: 740499c7 ("iomap: fix the iomap_readpage_actor return value for inline data")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
      d8af404f
  7. 18 10月, 2021 1 次提交
    • A
      iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable · a6294593
      由 Andreas Gruenbacher 提交于 
      Turn iov_iter_fault_in_readable into a function that returns the number
of bytes not faulted in, similar to copy_to_user, instead of returning a
non-zero value when any of the requested pages couldn't be faulted in.
This supports the existing users that require all pages to be faulted in
as well as new users that are happy if any pages can be faulted in.

Rename iov_iter_fault_in_readable to fault_in_iov_iter_readable to make
sure this change doesn't silently break things.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
      a6294593
  9. 17 8月, 2021 13 次提交
  11. 06 8月, 2021 2 次提交
  13. 04 8月, 2021 5 次提交
  15. 16 7月, 2021 3 次提交
  17. 30 6月, 2021 1 次提交
  19. 10 6月, 2021 1 次提交
  21. 03 6月, 2021 1 次提交
  23. 15 5月, 2021 1 次提交
  25. 04 5月, 2021 1 次提交
  27. 09 4月, 2021 1 次提交
  29. 11 3月, 2021 1 次提交
  31. 27 2月, 2021 1 次提交
  33. 26 2月, 2021 1 次提交
  35. 03 12月, 2020 1 次提交
    • R
      mm: memcontrol: Use helpers to read page's memcg data · bcfe06bf
      由 Roman Gushchin 提交于 
      Patch series "mm: allow mapping accounted kernel pages to userspace", v6.

Currently a non-slab kernel page which has been charged to a memory cgroup
can't be mapped to userspace.  The underlying reason is simple: PageKmemcg
flag is defined as a page type (like buddy, offline, etc), so it takes a
bit from a page->mapped counter.  Pages with a type set can't be mapped to
userspace.

But in general the kmemcg flag has nothing to do with mapping to
userspace.  It only means that the page has been accounted by the page
allocator, so it has to be properly uncharged on release.

Some bpf maps are mapping the vmalloc-based memory to userspace, and their
memory can't be accounted because of this implementation detail.

This patchset removes this limitation by moving the PageKmemcg flag into
one of the free bits of the page->mem_cgroup pointer.  Also it formalizes
accesses to the page->mem_cgroup and page->obj_cgroups using new helpers,
adds several checks and removes a couple of obsolete functions.  As the
result the code became more robust with fewer open-coded bit tricks.

This patch (of 4):

Currently there are many open-coded reads of the page->mem_cgroup pointer,
as well as a couple of read helpers, which are barely used.

It creates an obstacle on a way to reuse some bits of the pointer for
storing additional bits of information.  In fact, we already do this for
slab pages, where the last bit indicates that a pointer has an attached
vector of objcg pointers instead of a regular memcg pointer.

This commits uses 2 existing helpers and introduces a new helper to
converts all read sides to calls of these helpers:
  struct mem_cgroup *page_memcg(struct page *page);
  struct mem_cgroup *page_memcg_rcu(struct page *page);
  struct mem_cgroup *page_memcg_check(struct page *page);

page_memcg_check() is intended to be used in cases when the page can be a
slab page and have a memcg pointer pointing at objcg vector.  It does
check the lowest bit, and if set, returns NULL.  page_memcg() contains a
VM_BUG_ON_PAGE() check for the page not being a slab page.

To make sure nobody uses a direct access, struct page's
mem_cgroup/obj_cgroups is converted to unsigned long memcg_data.
Signed-off-by: NRoman Gushchin <guro@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Link: https://lkml.kernel.org/r/20201027001657.3398190-1-guro@fb.com
Link: https://lkml.kernel.org/r/20201027001657.3398190-2-guro@fb.com
Link: https://lore.kernel.org/bpf/20201201215900.3569844-2-guro@fb.com
      bcfe06bf
  37. 05 11月, 2020 2 次提交
    • B
      iomap: clean up writeback state logic on writepage error · 50e7d6c7
      由 Brian Foster 提交于 
      The iomap writepage error handling logic is a mash of old and
slightly broken XFS writepage logic. When keepwrite writeback state
tracking was introduced in XFS in commit 0d085a52 ("xfs: ensure
WB_SYNC_ALL writeback handles partial pages correctly"), XFS had an
additional cluster writeback context that scanned ahead of
->writepage() to process dirty pages over the current ->writepage()
extent mapping. This context expected a dirty page and required
retention of the TOWRITE tag on partial page processing so the
higher level writeback context would revisit the page (in contrast
to ->writepage(), which passes a page with the dirty bit already
cleared).

The cluster writeback mechanism was eventually removed and some of
the error handling logic folded into the primary writeback path in
commit 150d5be0 ("xfs: remove xfs_cancel_ioend"). This patch
accidentally conflated the two contexts by using the keepwrite logic
in ->writepage() without accounting for the fact that the page is
not dirty. Further, the keepwrite logic has no practical effect on
the core ->writepage() caller (write_cache_pages()) because it never
revisits a page in the current function invocation.

Technically, the page should be redirtied for the keepwrite logic to
have any effect. Otherwise, write_cache_pages() may find the tagged
page but will skip it since it is clean. Even if the page was
redirtied, however, there is still no practical effect to keepwrite
since write_cache_pages() does not wrap around within a single
invocation of the function. Therefore, the dirty page would simply
end up retagged on the next writeback sequence over the associated
range.

All that being said, none of this really matters because redirtying
a partially processed page introduces a potential infinite redirty
-> writeback failure loop that deviates from the current design
principle of clearing the dirty state on writepage failure to avoid
building up too much dirty, unreclaimable memory on the system.
Therefore, drop the spurious keepwrite usage and dirty state
clearing logic from iomap_writepage_map(), treat the partially
processed page the same as a fully processed page, and let the
imminent ioend failure clean up the writeback state.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
      50e7d6c7
    • B
      iomap: support partial page discard on writeback block mapping failure · 763e4cdc
      由 Brian Foster 提交于 
      iomap writeback mapping failure only calls into ->discard_page() if
the current page has not been added to the ioend. Accordingly, the
XFS callback assumes a full page discard and invalidation. This is
problematic for sub-page block size filesystems where some portion
of a page might have been mapped successfully before a failure to
map a delalloc block occurs. ->discard_page() is not called in that
error scenario and the bio is explicitly failed by iomap via the
error return from ->prepare_ioend(). As a result, the filesystem
leaks delalloc blocks and corrupts the filesystem block counters.

Since XFS is the only user of ->discard_page(), tweak the semantics
to invoke the callback unconditionally on mapping errors and provide
the file offset that failed to map. Update xfs_discard_page() to
discard the corresponding portion of the file and pass the range
along to iomap_invalidatepage(). The latter already properly handles
both full and sub-page scenarios by not changing any iomap or page
state on sub-page invalidations.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
      763e4cdc