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filemap: check compound_head(page)->mapping in pagecache_get_page() 

Similar to previous patch, pagecache_get_page() avoids race condition with
truncate by checking page->mapping == mapping.  This does not work for
compound pages.  This patch let it check compound_head(page)->mapping
instead.

Link: http://lkml.kernel.org/r/20190801184244.3169074-3-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Song Liu 2019-09-23 15:37:47 -07:00 committed by Linus Torvalds
parent 585e5a7bab
commit 31895438e7
1 changed files with 1 additions and 1 deletions
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2
mm/filemap.c
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@ -1647,7 +1647,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
} }
/* Has the page been truncated? */ /* Has the page been truncated? */
if (unlikely(page->mapping != mapping)) { if (unlikely(compound_head(page)->mapping != mapping)) {
unlock_page(page); unlock_page(page);
put_page(page); put_page(page);
goto repeat; goto repeat;