aio: fix race in ring buffer page lookup introduced by page migration support

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Prior to the introduction of page migration support in "fs/aio: Add support
to aio ring pages migration" / 36bc08cc01,
mapping of the ring buffer pages was done via get_user_pages() while
retaining mmap_sem held for write.  This avoided possible races with userland
racing an munmap() or mremap().  The page migration patch, however, switched
to using mm_populate() to prime the page mapping.  mm_populate() cannot be
called with mmap_sem held.

Instead of dropping the mmap_sem, revert to the old behaviour and simply
drop the use of mm_populate() since get_user_pages() will cause the pages to
get mapped anyways.  Thanks to Al Viro for spotting this issue.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>

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This commit is contained in:

Benjamin LaHaise 2013-09-09 11:57:59 -04:00

parent 77d30b14d2

commit d6c355c7da

1 changed files with 12 additions and 3 deletions

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fs/aio.c

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