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authorRalph Campbell <rcampbell@nvidia.com>2020-10-13 16:56:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 18:38:33 -0700
commita9b576f7253e22528584f5aeb46edf0b6b007992 (patch)
tree8330e51264c87e3be6efe80cf546a470ad83605a /lib/Makefile
parent30d8ec73e8772b32a7eae626d14004bd37d8f13c (diff)
downloadlinux-a9b576f7253e22528584f5aeb46edf0b6b007992.tar.gz
mm: move call to compound_head() in release_pages()
The function is_huge_zero_page() doesn't call compound_head() to make sure
the page pointer is a head page. The call to is_huge_zero_page() in
release_pages() is made before compound_head() is called so the test would
fail if release_pages() was called with a tail page of the huge_zero_page
and put_page_testzero() would be called releasing the page.
This is unlikely to be happening in normal use or we would be seeing all
sorts of process data corruption when accessing a THP zero page.

Looking at other places where is_huge_zero_page() is called, all seem to
only pass a head page so I think the right solution is to move the call
to compound_head() in release_pages() to a point before calling
is_huge_zero_page().

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20200917173938.16420-1-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/Makefile')
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