From: Minchan Kim <minchan@kernel.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Christoph Lameter <cl@linux.com>,
Android Kernel Team <kernel-team@android.com>,
Robert Love <rlove@google.com>, Mel Gorman <mel@csn.ul.ie>,
Hugh Dickins <hughd@google.com>,
Dave Hansen <dave@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>,
Dave Chinner <david@fromorbit.com>, Neil Brown <neilb@suse.de>,
Mike Hommey <mh@glandium.org>, Taras Glek <tglek@mozilla.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [RFC v2] Support volatile range for anon vma
Date: Tue, 11 Dec 2012 13:40:44 +0900 [thread overview]
Message-ID: <20121211044044.GC22698@blaptop> (raw)
In-Reply-To: <50C28EB4.6030505@linaro.org>
On Fri, Dec 07, 2012 at 04:49:56PM -0800, John Stultz wrote:
> On 12/04/2012 08:18 PM, Minchan Kim wrote:
> >On Tue, Dec 04, 2012 at 11:13:40AM -0800, John Stultz wrote:
> >>I don't think the problem is when vmas being marked VM_VOLATILE are
> >>being merged, its that when we mark the vma as *non-volatile*, and
> >>remove the VM_VOLATILE flag we merge the non-volatile vmas with
> >>neighboring vmas. So preserving the purged flag during that merge is
> >>important. Again, the example I used to trigger this was an
> >>alternating pattern of volatile and non volatile vmas, then marking
> >>the entire range non-volatile (though sometimes in two overlapping
> >>passes).
> >Understood. Thanks.
> >Below patch solves your problems? It's simple than yours.
>
> Yea, this is nicer then my fix.
> Although I still need the purged handling in the vma merge code for
> me to see the behavior I expect in my tests.
>
> I've integrated your patch and repushed my queue here:
> http://git.linaro.org/gitweb?p=people/jstultz/android-dev.git;a=shortlog;h=refs/heads/dev/minchan-anonvol
>
> git://git.linaro.org/people/jstultz/android-dev.git dev/minchan-anonvol
>
> >Anyway, both yours and mine are not right fix.
> >As I mentioned, locking scheme is broken.
> >We need anon_vma_lock to handle purged and we should consider fork
> >case, too.
> Hrm. I'm sure you're right, as I've not yet fully grasped all the
> locking rules here. Could you clarify how it is broken? And why is
> the anon_vma_lock needed to manage the purged state that is part of
> the vma itself?
If you don't hold anon->lock, merge/split/fork can race with try_to_unmap
so vma->[purged|vm_flags] would lose consistency.
>
> thanks
> -john
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
--
Kind regards,
Minchan Kim
--
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WARNING: multiple messages have this Message-ID (diff)
From: Minchan Kim <minchan@kernel.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Christoph Lameter <cl@linux.com>,
Android Kernel Team <kernel-team@android.com>,
Robert Love <rlove@google.com>, Mel Gorman <mel@csn.ul.ie>,
Hugh Dickins <hughd@google.com>,
Dave Hansen <dave@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>,
Dave Chinner <david@fromorbit.com>, Neil Brown <neilb@suse.de>,
Mike Hommey <mh@glandium.org>, Taras Glek <tglek@mozilla.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [RFC v2] Support volatile range for anon vma
Date: Tue, 11 Dec 2012 13:40:44 +0900 [thread overview]
Message-ID: <20121211044044.GC22698@blaptop> (raw)
In-Reply-To: <50C28EB4.6030505@linaro.org>
On Fri, Dec 07, 2012 at 04:49:56PM -0800, John Stultz wrote:
> On 12/04/2012 08:18 PM, Minchan Kim wrote:
> >On Tue, Dec 04, 2012 at 11:13:40AM -0800, John Stultz wrote:
> >>I don't think the problem is when vmas being marked VM_VOLATILE are
> >>being merged, its that when we mark the vma as *non-volatile*, and
> >>remove the VM_VOLATILE flag we merge the non-volatile vmas with
> >>neighboring vmas. So preserving the purged flag during that merge is
> >>important. Again, the example I used to trigger this was an
> >>alternating pattern of volatile and non volatile vmas, then marking
> >>the entire range non-volatile (though sometimes in two overlapping
> >>passes).
> >Understood. Thanks.
> >Below patch solves your problems? It's simple than yours.
>
> Yea, this is nicer then my fix.
> Although I still need the purged handling in the vma merge code for
> me to see the behavior I expect in my tests.
>
> I've integrated your patch and repushed my queue here:
> http://git.linaro.org/gitweb?p=people/jstultz/android-dev.git;a=shortlog;h=refs/heads/dev/minchan-anonvol
>
> git://git.linaro.org/people/jstultz/android-dev.git dev/minchan-anonvol
>
> >Anyway, both yours and mine are not right fix.
> >As I mentioned, locking scheme is broken.
> >We need anon_vma_lock to handle purged and we should consider fork
> >case, too.
> Hrm. I'm sure you're right, as I've not yet fully grasped all the
> locking rules here. Could you clarify how it is broken? And why is
> the anon_vma_lock needed to manage the purged state that is part of
> the vma itself?
If you don't hold anon->lock, merge/split/fork can race with try_to_unmap
so vma->[purged|vm_flags] would lose consistency.
>
> thanks
> -john
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
--
Kind regards,
Minchan Kim
next prev parent reply other threads:[~2012-12-11 4:40 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-30 1:29 [RFC v2] Support volatile range for anon vma Minchan Kim
2012-10-30 1:29 ` Minchan Kim
2012-10-31 21:35 ` Andrew Morton
2012-10-31 21:35 ` Andrew Morton
2012-10-31 21:59 ` Paul Turner
2012-10-31 21:59 ` Paul Turner
2012-10-31 22:56 ` KOSAKI Motohiro
2012-10-31 22:56 ` KOSAKI Motohiro
2012-11-01 1:15 ` Paul Turner
2012-11-01 1:15 ` Paul Turner
2012-11-01 1:46 ` Minchan Kim
2012-11-01 1:46 ` Minchan Kim
2012-11-01 1:25 ` Minchan Kim
2012-11-01 1:25 ` Minchan Kim
2012-11-01 2:01 ` KOSAKI Motohiro
2012-11-01 2:01 ` KOSAKI Motohiro
2012-11-05 23:54 ` Arun Sharma
2012-11-05 23:54 ` Arun Sharma
2012-11-06 1:49 ` Minchan Kim
2012-11-06 1:49 ` Minchan Kim
2012-11-06 2:03 ` Arun Sharma
2012-11-06 2:03 ` Arun Sharma
2012-11-01 0:50 ` Minchan Kim
2012-11-01 0:50 ` Minchan Kim
2012-11-01 1:22 ` Paul Turner
2012-11-01 1:22 ` Paul Turner
2012-11-01 1:33 ` Minchan Kim
2012-11-01 1:33 ` Minchan Kim
2012-11-01 0:21 ` Minchan Kim
2012-11-01 0:21 ` Minchan Kim
2012-11-02 1:43 ` Bob Liu
2012-11-02 1:43 ` Bob Liu
2012-11-02 2:37 ` Minchan Kim
2012-11-02 2:37 ` Minchan Kim
2012-11-22 0:36 ` John Stultz
2012-11-22 0:36 ` John Stultz
2012-11-29 4:18 ` John Stultz
2012-11-29 4:18 ` John Stultz
2012-12-04 0:00 ` Minchan Kim
2012-12-04 0:00 ` Minchan Kim
2012-12-04 0:57 ` John Stultz
2012-12-04 0:57 ` John Stultz
2012-12-04 7:22 ` Minchan Kim
2012-12-04 7:22 ` Minchan Kim
2012-12-04 19:13 ` John Stultz
2012-12-04 19:13 ` John Stultz
2012-12-05 4:18 ` Minchan Kim
2012-12-05 4:18 ` Minchan Kim
2012-12-08 0:49 ` John Stultz
2012-12-08 0:49 ` John Stultz
2012-12-11 4:40 ` Minchan Kim [this message]
2012-12-11 4:40 ` Minchan Kim
2012-12-05 7:01 ` Minchan Kim
2012-12-05 7:01 ` Minchan Kim
2012-12-08 0:20 ` John Stultz
2012-12-08 0:20 ` John Stultz
2012-12-11 4:34 ` Minchan Kim
2012-12-11 4:34 ` Minchan Kim
2012-12-03 23:50 ` Minchan Kim
2012-12-03 23:50 ` Minchan Kim
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