Commit 31895438 authored Sep 23, 2019 by Song Liu Committed by Linus Torvalds Sep 24, 2019

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>

parent 585e5a7b

mm/filemap.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1647,7 +1647,7 @@ repeat:
		}

		/* Has the page been truncated? */
		if (unlikely(page->mapping != mapping)) {
		if (unlikely(compound_head(page)->mapping != mapping)) {
		unlock_page(page);
		put_page(page);
		goto repeat;

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