The patch titled
Subject: mm, vmscan: unlock page while waiting on writeback
has been added to the -mm tree. Its filename is
mm-vmscan-unlock-page-while-waiting-on-writeback.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-vmscan-unlock-page-while-waiting-on-writeback.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmscan-unlock-page-while-waiting-on-writeback.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 ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm, vmscan: unlock page while waiting on writeback
This is merely a politeness: I've not found that shrink_page_list() leads
to deadlock with the page it holds locked across wait_on_page_writeback();
but nevertheless, why hold others off by keeping the page locked there?
And while we're at it: remove the mistaken "not " from the commentary on
this Case 3 (and a distracting blank line from Case 2, if I may).
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff -puN mm/vmscan.c~mm-vmscan-unlock-page-while-waiting-on-writeback mm/vmscan.c
--- a/mm/vmscan.c~mm-vmscan-unlock-page-while-waiting-on-writeback
+++ a/mm/vmscan.c
@@ -982,7 +982,7 @@ static unsigned long shrink_page_list(st
* __GFP_IO|__GFP_FS for this reason); but more thought
* would probably show more reasons.
*
- * 3) Legacy memcg encounters a page that is not already marked
+ * 3) Legacy memcg encounters a page that is already marked
* PageReclaim. memcg does not have any dirty pages
* throttling so we could easily OOM just because too many
* pages are in writeback and there is nothing else to
@@ -1012,12 +1012,15 @@ static unsigned long shrink_page_list(st
*/
SetPageReclaim(page);
nr_writeback++;
-
goto keep_locked;
/* Case 3 above */
} else {
+ unlock_page(page);
wait_on_page_writeback(page);
+ /* then go back and try same page again */
+ list_add_tail(&page->lru, page_list);
+ continue;
}
}
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
mm-fix-potential-data-race-in-sys_swapon.patch
mm-vmscan-unlock-page-while-waiting-on-writeback.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
