This is a note to let you know that I've just added the patch titled
mm: numa: ensure anon_vma is locked to prevent parallel THP splits
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-numa-ensure-anon_vma-is-locked-to-prevent-parallel-thp-splits.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c3a489cac38d43ea6dc4ac240473b44b46deecf7 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@xxxxxxx>
Date: Wed, 18 Dec 2013 17:08:38 -0800
Subject: mm: numa: ensure anon_vma is locked to prevent parallel THP splits
From: Mel Gorman <mgorman@xxxxxxx>
commit c3a489cac38d43ea6dc4ac240473b44b46deecf7 upstream.
The anon_vma lock prevents parallel THP splits and any associated
complexity that arises when handling splits during THP migration. This
patch checks if the lock was successfully acquired and bails from THP
migration if it failed for any reason.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Alex Thorlton <athorlton@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1334,6 +1334,13 @@ int do_huge_pmd_numa_page(struct mm_stru
goto out_unlock;
}
+ /* Bail if we fail to protect against THP splits for any reason */
+ if (unlikely(!anon_vma)) {
+ put_page(page);
+ page_nid = -1;
+ goto clear_pmdnuma;
+ }
+
/*
* Migrate the THP to the requested node, returns with page unlocked
* and pmd_numa cleared.
Patches currently in stable-queue which might be from mgorman@xxxxxxx are
queue-3.12/sched-numa-skip-inaccessible-vmas.patch
queue-3.12/mm-clear-pmd_numa-before-invalidating.patch
queue-3.12/mm-numa-ensure-anon_vma-is-locked-to-prevent-parallel-thp-splits.patch
queue-3.12/mm-numa-avoid-unnecessary-work-on-the-failure-path.patch
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