Patch "mm, oom: stop pre-mature high-order OOM killer invocations" has been added to the 4.8-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mm, oom: stop pre-mature high-order OOM killer invocations

to the 4.8-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-oom-stop-pre-mature-high-order-oom-killer-invocations.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From mhocko@kernel.org  Tue Nov 29 17:42:17 2016
From: Michal Hocko <mhocko@kernel.org>
Date: Tue, 29 Nov 2016 17:25:15 +0100
Subject: mm, oom: stop pre-mature high-order OOM killer invocations
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Stable tree <stable@vger.kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, Marc MERLIN <marc@merlins.org>, linux-mm@kvack.org, Linus Torvalds <torvalds@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Tejun Heo <tj@kernel.org>
Message-ID: <20161129162515.GD9796@dhcp22.suse.cz>
Content-Disposition: inline

From: Michal Hocko <mhocko@suse.com>

31e49bfda184 ("mm, oom: protect !costly allocations some more for
!CONFIG_COMPACTION") was an attempt to reduce chances of pre-mature OOM
killer invocation for high order requests. It seemed to work for most
users just fine but it is far from bullet proof and obviously not
sufficient for Marc who has reported pre-mature OOM killer invocations
with 4.8 based kernels. 4.9 will all the compaction improvements seems
to be behaving much better but that would be too intrusive to backport
to 4.8 stable kernels. Instead this patch simply never declares OOM for
!costly high order requests. We rely on order-0 requests to do that in
case we are really out of memory. Order-0 requests are much more common
and so a risk of a livelock without any way forward is highly unlikely.

Reported-by: Marc MERLIN <marc@merlins.org>
Tested-by: Marc MERLIN <marc@merlins.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/page_alloc.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3161,6 +3161,16 @@ should_compact_retry(struct alloc_contex
 	if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
 		return false;
 
+#ifdef CONFIG_COMPACTION
+	/*
+	 * This is a gross workaround to compensate a lack of reliable compaction
+	 * operation. We cannot simply go OOM with the current state of the compaction
+	 * code because this can lead to pre mature OOM declaration.
+	 */
+	if (order <= PAGE_ALLOC_COSTLY_ORDER)
+		return true;
+#endif
+
 	/*
 	 * There are setups with compaction disabled which would prefer to loop
 	 * inside the allocator rather than hit the oom killer prematurely.


Patches currently in stable-queue which might be from mhocko@kernel.org are

queue-4.8/mm-oom-stop-pre-mature-high-order-oom-killer-invocations.patch