Re: [BUGFIX][mm][PATCH] fix migration race in rmap_walk
From: Minchan Kim
Date: Mon Apr 26 2010 - 05:48:49 EST
On Mon, Apr 26, 2010 at 6:28 PM, KAMEZAWA Hiroyuki
> On Mon, 26 Apr 2010 08:49:01 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>> On Sat, 24 Apr 2010 11:43:24 +0100
>> Mel Gorman <mel@xxxxxxxxx> wrote:
>> > It looks nice but it still broke after 28 hours of running. The
>> > seq-counter is still insufficient to catch all changes that are made to
>> > the list. I'm beginning to wonder if a) this really can be fully safely
>> > locked with the anon_vma changes and b) if it has to be a spinlock to
>> > catch the majority of cases but still a lazy cleanup if there happens to
>> > be a race. It's unsatisfactory and I'm expecting I'll either have some
>> > insight to the new anon_vma changes that allow it to be locked or Rik
>> > knows how to restore the original behaviour which as Andrea pointed out
>> > was safe.
> Ok, reproduced. Here is status in my test + printk().
> Â* A race doesn't seem to happen if swap=off.
> Â ÂI need to swapon to cause the bug
Do you have a swapon/off bomb test?
When I saw your mail, I feel it might be culprit.
It is just guessing. I don't have a time to look into, now.
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