From: Andi Kleen <andi@firstfloor.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@suse.de>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Andi Kleen <andi@firstfloor.org>,
"riel@redhat.com" <riel@redhat.com>,
"chris.mason@oracle.com" <chris.mason@oracle.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order
Date: Fri, 12 Jun 2009 12:03:08 +0200 [thread overview]
Message-ID: <20090612100308.GD25568@one.firstfloor.org> (raw)
In-Reply-To: <20090611144430.540500784@intel.com>
On Thu, Jun 11, 2009 at 10:22:41PM +0800, Wu Fengguang wrote:
> To avoid possible deadlock. Proposed by Nick Piggin:
I disagree with the description. There's no possible deadlock right now.
It would be purely out of paranoia.
>
> You have tasklist_lock(R) nesting outside i_mmap_lock, and inside anon_vma
> lock. And anon_vma lock nests inside i_mmap_lock.
>
> This seems fragile. If rwlocks ever become FIFO or tasklist_lock changes
I was a bit dubious on this reasoning. If rwlocks become FIFO a lot of
stuff will likely break.
> type (maybe -rt kernels do it), then you could have a task holding
I think they tried but backed off quickly again
It's ok with a less scare-mongering description.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@suse.de>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Andi Kleen <andi@firstfloor.org>,
"riel@redhat.com" <riel@redhat.com>,
"chris.mason@oracle.com" <chris.mason@oracle.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order
Date: Fri, 12 Jun 2009 12:03:08 +0200 [thread overview]
Message-ID: <20090612100308.GD25568@one.firstfloor.org> (raw)
In-Reply-To: <20090611144430.540500784@intel.com>
On Thu, Jun 11, 2009 at 10:22:41PM +0800, Wu Fengguang wrote:
> To avoid possible deadlock. Proposed by Nick Piggin:
I disagree with the description. There's no possible deadlock right now.
It would be purely out of paranoia.
>
> You have tasklist_lock(R) nesting outside i_mmap_lock, and inside anon_vma
> lock. And anon_vma lock nests inside i_mmap_lock.
>
> This seems fragile. If rwlocks ever become FIFO or tasklist_lock changes
I was a bit dubious on this reasoning. If rwlocks become FIFO a lot of
stuff will likely break.
> type (maybe -rt kernels do it), then you could have a task holding
I think they tried but backed off quickly again
It's ok with a less scare-mongering description.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
--
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next prev parent reply other threads:[~2009-06-12 9:55 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-11 14:22 [PATCH 0/5] [RFC] HWPOISON incremental fixes Wu Fengguang
2009-06-11 14:22 ` Wu Fengguang
2009-06-11 14:22 ` [PATCH 1/5] HWPOISON: define VM_FAULT_HWPOISON to 0 when feature is disabled Wu Fengguang
2009-06-11 14:22 ` Wu Fengguang
2009-06-11 15:44 ` Rik van Riel
2009-06-11 15:44 ` Rik van Riel
2009-06-12 10:00 ` Andi Kleen
2009-06-12 10:00 ` Andi Kleen
2009-06-12 13:15 ` Wu Fengguang
2009-06-12 13:15 ` Wu Fengguang
2009-06-12 11:22 ` Ingo Molnar
2009-06-12 11:22 ` Ingo Molnar
2009-06-12 12:57 ` Wu Fengguang
2009-06-12 12:57 ` Wu Fengguang
2009-06-12 13:17 ` Ingo Molnar
2009-06-12 13:17 ` Ingo Molnar
2009-06-12 13:33 ` Wu Fengguang
2009-06-12 13:33 ` Wu Fengguang
2009-06-12 15:36 ` Ingo Molnar
2009-06-12 15:36 ` Ingo Molnar
2009-06-12 16:14 ` Wu Fengguang
2009-06-12 16:14 ` Wu Fengguang
2009-06-12 18:07 ` Alan Cox
2009-06-12 18:07 ` Alan Cox
2009-06-12 17:55 ` Theodore Tso
2009-06-12 17:55 ` Theodore Tso
2009-06-12 13:58 ` Andi Kleen
2009-06-12 13:58 ` Andi Kleen
2009-06-12 15:28 ` Linus Torvalds
2009-06-12 15:28 ` Linus Torvalds
2009-06-12 15:35 ` Ingo Molnar
2009-06-12 15:35 ` Ingo Molnar
2009-06-12 16:05 ` Rik van Riel
2009-06-12 16:05 ` Rik van Riel
2009-06-12 16:37 ` H. Peter Anvin
2009-06-12 16:37 ` H. Peter Anvin
2009-06-12 16:48 ` Ingo Molnar
2009-06-12 16:48 ` Ingo Molnar
2009-06-15 7:04 ` Nick Piggin
2009-06-15 7:04 ` Nick Piggin
2009-06-15 6:52 ` Nick Piggin
2009-06-15 6:52 ` Nick Piggin
2009-06-16 20:27 ` Russ Anderson
2009-06-16 20:27 ` Russ Anderson
2009-06-17 7:51 ` Nick Piggin
2009-06-17 7:51 ` Nick Piggin
2009-06-12 15:45 ` Ingo Molnar
2009-06-12 15:45 ` Ingo Molnar
2009-06-12 16:12 ` Linus Torvalds
2009-06-12 16:12 ` Linus Torvalds
2009-06-11 14:22 ` [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order Wu Fengguang
2009-06-11 14:22 ` Wu Fengguang
2009-06-11 15:59 ` Rik van Riel
2009-06-11 15:59 ` Rik van Riel
2009-06-12 10:03 ` Andi Kleen [this message]
2009-06-12 10:03 ` Andi Kleen
2009-06-12 10:07 ` Nick Piggin
2009-06-12 10:07 ` Nick Piggin
2009-06-12 13:27 ` Wu Fengguang
2009-06-12 13:27 ` Wu Fengguang
2009-06-12 14:04 ` Wu Fengguang
2009-06-12 14:04 ` Wu Fengguang
2009-06-11 14:22 ` [PATCH 3/5] HWPOISON: remove early kill option for now Wu Fengguang
2009-06-11 14:22 ` Wu Fengguang
2009-06-11 16:06 ` Rik van Riel
2009-06-11 16:06 ` Rik van Riel
2009-06-12 9:59 ` Andi Kleen
2009-06-12 9:59 ` Andi Kleen
2009-06-11 14:22 ` [PATCH 4/5] HWPOISON: report sticky EIO for poisoned file Wu Fengguang
2009-06-11 14:22 ` Wu Fengguang
2009-06-11 16:31 ` Rik van Riel
2009-06-11 16:31 ` Rik van Riel
2009-06-12 10:07 ` Andi Kleen
2009-06-12 10:07 ` Andi Kleen
2009-06-12 13:41 ` Wu Fengguang
2009-06-12 13:41 ` Wu Fengguang
2009-06-11 14:22 ` [PATCH 5/5] HWPOISON: use the safer invalidate page for possible metadata pages Wu Fengguang
2009-06-11 14:22 ` Wu Fengguang
2009-06-11 16:36 ` Rik van Riel
2009-06-11 16:36 ` Rik van Riel
2009-06-12 10:56 ` [PATCH 0/5] [RFC] HWPOISON incremental fixes Andi Kleen
2009-06-12 10:56 ` Andi Kleen
2009-06-12 13:59 ` Wu Fengguang
2009-06-12 13:59 ` Wu Fengguang
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