The patch titled
mm: find_get_pages_contig fixlet
has been added to the -mm tree. Its filename is
mm-find_get_pages_contig-fixlet.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: find_get_pages_contig fixlet
From: Nick Piggin <npiggin@xxxxxxxxx>
Testing ->mapping and ->index without a ref is not stable as the page
may have been reused at this point.
Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>
Reviewed-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff -puN mm/filemap.c~mm-find_get_pages_contig-fixlet mm/filemap.c
--- a/mm/filemap.c~mm-find_get_pages_contig-fixlet
+++ a/mm/filemap.c
@@ -846,9 +846,6 @@ repeat:
if (radix_tree_deref_retry(page))
goto restart;
- if (page->mapping == NULL || page->index != index)
- break;
-
if (!page_cache_get_speculative(page))
goto repeat;
@@ -858,6 +855,16 @@ repeat:
goto repeat;
}
+ /*
+ * 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 == NULL || page->index != index) {
+ page_cache_release(page);
+ break;
+ }
+
pages[ret] = page;
ret++;
index++;
_
Patches currently in -mm which might be from npiggin@xxxxxxxxx are
atomic-add-atomic_inc_not_zero_hint.patch
radix-tree-fix-rcu-bug.patch
linux-next.patch
cifs-dont-overwrite-dentry-name-in-d_revalidate.patch
jfs-dont-overwrite-dentry-name-in-d_revalidate.patch
mm-find_get_pages_contig-fixlet.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
