Re: 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free

[Marc MERLIN <marc@merlins.org>]

On Mon, Nov 21, 2016 at 07:43:36AM -0800, Marc MERLIN wrote:
> Howdy,
> 
> As a followup to https://plus.google.com/u/0/+MarcMERLIN/posts/A3FrLVo3kc6
> 
> http://pastebin.com/yJybSHNq and http://pastebin.com/B6xEH4Dw
> show a system with plenty of RAM (24GB) falling over and killing inoccent
> user space apps, a few hours after I start a 9TB copy between 2 raid5 arrays 
> both hosting bcache, dmcrypt and btrfs (yes, that's 3 layers under btrfs)
> 
> This kind of stuff worked until 4.6 if I'm not mistaken and started failing
> with 4.8 (I didn't try 4.7)
> 
> I tried applying
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9f7e3387939b036faacf4e7f32de7bb92a6635d6
> to 4.8.8 and it didn't help
> http://pastebin.com/2LUicF3k

My apologies. I'm actually wrong on that one bit.
That patch didn't actually apply on my kernel and I didn't end up
testing it, due to the failure/revert, it was just another test of the
same 4.8.8, so a worthless test.

That part of the patch is not compatible with 4.8.8:
--- mm/compaction.c
+++ mm/compaction.c
@@ -1660,7 +1664,8 @@
 		.classzone_idx = classzone_idx,
 		.direct_compaction = true,
 		.whole_zone = (prio == MIN_COMPACT_PRIORITY),
-		.ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY)
+		.ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY),
+		.ignore_block_suitable = (prio == MIN_COMPACT_PRIORITY)
 	};
 	INIT_LIST_HEAD(&cc.freepages);
 	INIT_LIST_HEAD(&cc.migratepages);

Anyway, for now I'm going to test 
https://marc.info/?l=linux-mm&m=147423605024993
for real now (on top of 4.8.8)

If you'd like me to re-test the compaction patch with 4.8.8, please give
me one that is compatible with 4.8.8 but in the meantime, I'll try that
2nd patch on 4.8.8 and report back.

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901

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