From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
Mel Gorman <mgorman@suse.de>,
Pavel Emelyanov <xemul@parallels.com>,
gnome@rvzt.net, drawoc@darkrefraction.com,
alan@lxorguk.ukuu.org.uk, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
bugzilla-daemon@bugzilla.kernel.org
Subject: Re: [Bug 67651] Bisected: Lots of fragmented mmaps cause gimp to fail in 3.12 after exceeding vm_max_map_count
Date: Thu, 23 Jan 2014 10:27:46 +0400 [thread overview]
Message-ID: <20140123062746.GT1574@moon> (raw)
In-Reply-To: <20140122220910.198121ee.akpm@linux-foundation.org>
On Wed, Jan 22, 2014 at 10:09:10PM -0800, Andrew Morton wrote:
> > >
> > > That being said, this could cause vma blowups for programs that are
> > > actually using this thing.
> >
> > Hi Andy, indeed, this could happen. The easiest way is to ignore softdirty bit
> > when we're trying to merge vmas and set it one new merged. I think this should
> > be correct. Once I finish I'll send the patch.
>
> Hang on. We think the problem is that gimp is generating vmas which
> *should* be merged, but for unknown reasons they differ in
> VM_SOFTDIRTY, yes?
Yes. One place where I forgot to set softdirty bit is setup_arg_pages. But
it called once on elf load, so it can't cause such effect (but should be
fixed too). Also there is do_brk where vmasoftdirty is missed too :/
Another problem is the potential scenario when we have a bunch of vmas
and clear vma-softdirty bit on them, then we try to map new one, flags
won't match and instead of extending old vma the new one will be created.
I think (if only I'm not missing something) that vma-softdirty should
be ignored in such case (ie inside is_mergeable_vma) and once vma extended
it should be marked as dirty one. Again, I need to think and test more.
> Shouldn't we work out where we're forgetting to set VM_SOFTDIRTY?
> Putting bandaids over this error when we come to trying to merge the
> vmas sounds very wrong?
I'm looking into this as well.
Cyrill
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next prev parent reply other threads:[~2014-01-23 6:27 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-22 19:08 [Bug 67651] Bisected: Lots of fragmented mmaps cause gimp to fail in 3.12 after exceeding vm_max_map_count Mel Gorman
2014-01-22 19:19 ` Cyrill Gorcunov
2014-01-22 22:33 ` Cyrill Gorcunov
2014-01-23 9:55 ` Mel Gorman
2014-01-23 10:36 ` Cyrill Gorcunov
2014-01-23 12:15 ` Cyrill Gorcunov
2014-01-23 12:55 ` Cyrill Gorcunov
2014-01-23 15:14 ` [PATCH] mm: Ignore VM_SOFTDIRTY on VMA merging, v2 Cyrill Gorcunov
2014-01-23 18:07 ` Pavel Emelyanov
2014-01-23 21:02 ` Andrew Morton
2014-01-23 21:45 ` Cyrill Gorcunov
2014-01-24 10:14 ` Mel Gorman
2014-01-24 11:56 ` Cyrill Gorcunov
2014-01-24 13:41 ` Mel Gorman
2014-01-24 14:23 ` Cyrill Gorcunov
2014-01-23 10:30 ` [Bug 67651] Bisected: Lots of fragmented mmaps cause gimp to fail in 3.12 after exceeding vm_max_map_count Mel Gorman
2014-01-22 19:52 ` Andrew Morton
2014-01-23 7:28 ` Mel Gorman
2014-01-22 22:45 ` Andy Lutomirski
2014-01-23 5:59 ` Cyrill Gorcunov
2014-01-23 6:09 ` Andrew Morton
2014-01-23 6:27 ` Cyrill Gorcunov [this message]
2022-11-21 17:23 ` Muhammad Usama Anjum
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