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author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-10-06 22:53:14 +0300 |
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committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-19 00:34:14 +0300 |
commit | 164b06f238b986317131e6b61b2f22aabcbc2cc0 (patch) | |
tree | 44cf8d09d2943df9bb5221287c89f30d99042a36 /mm/page_table_check.c | |
parent | 5d74b2ab2c15d596c470bae6626f345d5575a9d0 (diff) | |
download | linux-164b06f238b986317131e6b61b2f22aabcbc2cc0.tar.xz |
mm: call wp_page_copy() under the VMA lock
It is usually safe to call wp_page_copy() under the VMA lock. The only
unsafe situation is when no anon_vma has been allocated for this VMA, and
we have to look at adjacent VMAs to determine if their anon_vma can be
shared. Since this happens only for the first COW of a page in this VMA,
the majority of calls to wp_page_copy() do not need to fall back to the
mmap_sem.
Add vmf_anon_prepare() as an alternative to anon_vma_prepare() which will
return RETRY if we currently hold the VMA lock and need to allocate an
anon_vma. This lets us drop the check in do_wp_page().
Link: https://lkml.kernel.org/r/20231006195318.4087158-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/page_table_check.c')
0 files changed, 0 insertions, 0 deletions