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| author |   Matthew Wilcox <willy@infradead.org> | 2019-03-05 15:44:08 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-05 21:07:16 -0800 |
| commit | 14ef1fc72a3e86cea6498193c5e04b4619cb8622 (patch) | |
| tree | 51dca5e31d99fc92626bfe7c3eebfb4543201554 | |
| parent | mm/memcontrol.c: use struct_size() in kmalloc() (diff) | |
| download | linux-dev-14ef1fc72a3e86cea6498193c5e04b4619cb8622.tar.xz linux-dev-14ef1fc72a3e86cea6498193c5e04b4619cb8622.zip | |
mm/filemap.c: remove redundant test from find_get_pages_contig
After we establish a reference on the page, we check the pointer
continues to be in the correct position in i_pages. Checking
page->index afterwards is unnecessary; if it were to change, then the
pointer to it from the page cache would also move. The check used to be
done before grabbing a reference on the page which was racy (see commit
9cbb4cb21b19f ("mm: find_get_pages_contig fixlet")), but nobody noticed
that moving the check after grabbing the reference was redundant.
Link: http://lkml.kernel.org/r/20190107200224.13260-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/filemap.c | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 9f5e323e883e..935fbc29aeb1 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1837,16 +1837,6 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, if (unlikely(page != xas_reload(&xas))) goto put_page; - /* - * must check mapping and index after taking the ref. - * otherwise we can get both false positives and false - * negatives, which is just confusing to the caller. - */ - if (!page->mapping || page_to_pgoff(page) != xas.xa_index) { - put_page(page); - break; - } - pages[ret] = page; if (++ret == nr_pages) break; |