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From: Andrew Morton <akpm@linux-foundation.org>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: linux-mm@kvack.org, Dave Jones <davej@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Pekka Enberg <penberg@kernel.org>
Subject: Re: OOM killer even when not overcommiting
Date: Mon, 5 Mar 2012 12:04:27 -0800	[thread overview]
Message-ID: <20120305120427.2d11d30e.akpm@linux-foundation.org> (raw)
In-Reply-To: <1330977506.1589.59.camel@lappy>

On Mon, 05 Mar 2012 21:58:26 +0200
Sasha Levin <levinsasha928@gmail.com> wrote:

> Hi all,

> I assumed that when setting overcommit_memory=2 and
> overcommit_ratio<100 that the OOM killer won't ever get invoked (since
> we're not overcommiting memory), but it looks like I'm mistaken since
> apparently a simple mmap from userspace will trigger the OOM killer if
> it requests more memory than available.
>
> Is it how it's supposed to work?  Why does it resort to OOM killing
> instead of just failing the allocation?
>
> Here is the dump I get when the OOM kicks in:
> 
> ...
>
> [ 3108.730350]  [<ffffffff81198e4a>] mlock_vma_pages_range+0x9a/0xa0
> [ 3108.734486]  [<ffffffff8119b75b>] mmap_region+0x28b/0x510
> ...

The vma is mlocked for some reason - presumably the app is using
mlockall() or mlock()?  So the kernel is trying to instantiate all the
pages at mmap() time.


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WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: linux-mm@kvack.org, Dave Jones <davej@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Pekka Enberg <penberg@kernel.org>
Subject: Re: OOM killer even when not overcommiting
Date: Mon, 5 Mar 2012 12:04:27 -0800	[thread overview]
Message-ID: <20120305120427.2d11d30e.akpm@linux-foundation.org> (raw)
In-Reply-To: <1330977506.1589.59.camel@lappy>

On Mon, 05 Mar 2012 21:58:26 +0200
Sasha Levin <levinsasha928@gmail.com> wrote:

> Hi all,

> I assumed that when setting overcommit_memory=2 and
> overcommit_ratio<100 that the OOM killer won't ever get invoked (since
> we're not overcommiting memory), but it looks like I'm mistaken since
> apparently a simple mmap from userspace will trigger the OOM killer if
> it requests more memory than available.
>
> Is it how it's supposed to work?  Why does it resort to OOM killing
> instead of just failing the allocation?
>
> Here is the dump I get when the OOM kicks in:
> 
> ...
>
> [ 3108.730350]  [<ffffffff81198e4a>] mlock_vma_pages_range+0x9a/0xa0
> [ 3108.734486]  [<ffffffff8119b75b>] mmap_region+0x28b/0x510
> ...

The vma is mlocked for some reason - presumably the app is using
mlockall() or mlock()?  So the kernel is trying to instantiate all the
pages at mmap() time.



  reply	other threads:[~2012-03-05 20:04 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-05 19:58 OOM killer even when not overcommiting Sasha Levin
2012-03-05 19:58 ` Sasha Levin
2012-03-05 20:04 ` Andrew Morton [this message]
2012-03-05 20:04   ` Andrew Morton
2012-03-05 20:13   ` Sasha Levin
2012-03-05 20:13     ` Sasha Levin

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