linux-kernel - Re: [PATCH] zsmalloc: fix migrate_zspage-zs

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Date:	Wed, 20 Jan 2016 16:00:19 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Russell Knize <rknize@...orola.com>
Cc:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Junil Lee <junil0814.lee@....com>,
	Andrew Morton <akpm@...ux-foundation.org>, ngupta@...are.org,
	linux-mm@...ck.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition

Hello Russ,

On Tue, Jan 19, 2016 at 09:47:12AM -0600, Russell Knize wrote:
>    Just wanted to ack this, as we have been seeing the same problem (weird
>    race conditions during compaction) and fixed it in the same way a few
>    weeks ago (resetting the pin bit before recording the obj).
>    Russ

First of all, thanks for your comment.

The patch you tested have a problem although it's really subtle(ie,
it doesn't do store tearing when I disassemble ARM{32|64}) but it
could have a problem potentially for other architecutres or future ARM.
For right fix, I sent v5 - https://lkml.org/lkml/2016/1/18/263.
If you can prove it fixes your problem, please Tested-by to the thread.
It's really valuable to do testing for stable material.

Thanks!