From: Chris Mason <chris.mason@oracle.com>
To: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-nfs@vger.kernel.org
Subject: Re: [PATCH] VM: kswapd should not do blocking memory allocations
Date: Wed, 18 Aug 2010 15:34:40 -0400 [thread overview]
Message-ID: <20100818193440.GZ5854@think> (raw)
In-Reply-To: <1282158241.8540.85.camel@heimdal.trondhjem.org>
On Wed, Aug 18, 2010 at 03:04:01PM -0400, Trond Myklebust wrote:
> From: Trond Myklebust <Trond.Myklebust@netapp.com>
>
> Allowing kswapd to do GFP_KERNEL memory allocations (or any blocking memory
> allocations) is wrong and can cause deadlocks in try_to_release_page(), as
> the filesystem believes it is safe to allocate new memory and block,
> whereas kswapd is there specifically to clear a low-memory situation...
>
> Set the gfp_mask to GFP_IOFS instead.
I always thought releasepage was supposed to do almost zero work. It
could release an instantly freeable page but it wasn't supposed to dive
in and solve world hunger or anything.
I thought the VM would be using writepage for that.
-chris
WARNING: multiple messages have this Message-ID (diff)
From: Chris Mason <chris.mason@oracle.com>
To: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-nfs@vger.kernel.org
Subject: Re: [PATCH] VM: kswapd should not do blocking memory allocations
Date: Wed, 18 Aug 2010 15:34:40 -0400 [thread overview]
Message-ID: <20100818193440.GZ5854@think> (raw)
In-Reply-To: <1282158241.8540.85.camel@heimdal.trondhjem.org>
On Wed, Aug 18, 2010 at 03:04:01PM -0400, Trond Myklebust wrote:
> From: Trond Myklebust <Trond.Myklebust@netapp.com>
>
> Allowing kswapd to do GFP_KERNEL memory allocations (or any blocking memory
> allocations) is wrong and can cause deadlocks in try_to_release_page(), as
> the filesystem believes it is safe to allocate new memory and block,
> whereas kswapd is there specifically to clear a low-memory situation...
>
> Set the gfp_mask to GFP_IOFS instead.
I always thought releasepage was supposed to do almost zero work. It
could release an instantly freeable page but it wasn't supposed to dive
in and solve world hunger or anything.
I thought the VM would be using writepage for that.
-chris
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next prev parent reply other threads:[~2010-08-18 19:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-18 19:04 [PATCH] VM: kswapd should not do blocking memory allocations Trond Myklebust
2010-08-18 19:04 ` Trond Myklebust
[not found] ` <AANLkTi=WkoxjwZbt6Vd0VhbuA7_k2WM-NUXZnrmzOOPy@mail.gmail.com>
2010-08-18 19:31 ` Trond Myklebust
2010-08-18 19:31 ` Trond Myklebust
2010-08-20 5:45 ` Wu Fengguang
2010-08-20 5:45 ` Wu Fengguang
2010-08-20 12:17 ` Trond Myklebust
2010-08-20 12:17 ` Trond Myklebust
2010-08-18 19:34 ` Chris Mason [this message]
2010-08-18 19:34 ` Chris Mason
2010-08-18 20:10 ` Trond Myklebust
2010-08-18 20:10 ` Trond Myklebust
2010-08-20 5:40 ` Wu Fengguang
2010-08-20 5:40 ` Wu Fengguang
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