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| author | Hugh Dickins | 2014-06-23 22:22:06 +0200 |
|---|---|---|
| committer | Linus Torvalds | 2014-06-24 01:47:44 +0200 |
| commit | f00cdc6df7d7cfcabb5b740911e6788cb0802bdb (patch) | |
| tree | 2d540f918e013b5dcca920e904c264c703c794eb /mm/slab.c | |
| parent | mm: let mm_find_pmd fix buggy race with THP fault (diff) | |
| download | kernel-qcow2-linux-f00cdc6df7d7cfcabb5b740911e6788cb0802bdb.tar.gz kernel-qcow2-linux-f00cdc6df7d7cfcabb5b740911e6788cb0802bdb.tar.xz kernel-qcow2-linux-f00cdc6df7d7cfcabb5b740911e6788cb0802bdb.zip | |
shmem: fix faulting into a hole while it's punched
Trinity finds that mmap access to a hole while it's punched from shmem
can prevent the madvise(MADV_REMOVE) or fallocate(FALLOC_FL_PUNCH_HOLE)
from completing, until the reader chooses to stop; with the puncher's
hold on i_mutex locking out all other writers until it can complete.
It appears that the tmpfs fault path is too light in comparison with its
hole-punching path, lacking an i_data_sem to obstruct it; but we don't
want to slow down the common case.
Extend shmem_fallocate()'s existing range notification mechanism, so
shmem_fault() can refrain from faulting pages into the hole while it's
punched, waiting instead on i_mutex (when safe to sleep; or repeatedly
faulting when not).
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.c')
0 files changed, 0 insertions, 0 deletions