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From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Avi Kivity <avi@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
	Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@elte.hu>,
	akpm@linux-foundation.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	David Miller <davem@davemloft.net>,
	Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Nick Piggin <npiggin@suse.de>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH 10/28] mm: Make use of the anon_vma ref count
Date: Wed, 09 Jun 2010 15:32:27 +0200	[thread overview]
Message-ID: <1276090347.1645.582.camel@laptop> (raw)
In-Reply-To: <20100609132245.GF5650@csn.ul.ie>

On Wed, 2010-06-09 at 14:22 +0100, Mel Gorman wrote:
> This comment is no longer strictly correct. anon_vma_alloc() can also be
> called from anon_vma_fork where the root of the newly allocated anon_vma
> will be set to the same as the parents anon_vma. Maybe something like
> 
> /*
>  * Initialise the anon_vma root to point to itself. If called from
>  * fork, the root will be reset to the parents anon_vma 
>  */

Sure, I'll change the comment.

> Else, just leave the initialisation of the root where it was but only
> init the refcount here.

Ah, that would lead to problems. We use put_anon_vma() to free in the
create error path, and __put_anon_vma() will also check the
anon_vma->root, so by not setting it the error path will explode.

  reply	other threads:[~2010-06-09 13:33 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-07 11:06 [PATCH 00/28] mm: preemptibility -v3 Peter Zijlstra
2010-06-07 11:06 ` Peter Zijlstra
2010-06-07 11:06 ` [PATCH 01/28] powerpc: Use call_rcu_sched() for pagetables Peter Zijlstra
2010-06-07 11:06   ` Peter Zijlstra
2010-06-07 11:06 ` [PATCH 02/28] mm: Improve page_lock_anon_vma() comment Peter Zijlstra
2010-06-07 11:06   ` Peter Zijlstra
2010-06-09 10:50   ` Mel Gorman
2010-06-07 11:06 ` [PATCH 03/28] rename anon_vma_lock to vma_lock_anon_vma Peter Zijlstra
2010-06-07 11:06   ` Peter Zijlstra
2010-06-07 15:01   ` Peter Zijlstra
2010-06-09 10:59   ` Mel Gorman
2010-06-07 11:06 ` [PATCH 04/28] change direct call of spin_lock(anon_vma->lock) to inline function Peter Zijlstra
2010-06-07 11:06   ` Peter Zijlstra
2010-06-07 11:06 ` [PATCH 05/28] track the root (oldest) anon_vma Peter Zijlstra
2010-06-07 11:06   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 06/28] always lock " Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 07/28] extend KSM refcounts to the anon_vma root Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-09 10:55   ` Mel Gorman
2010-06-07 11:07 ` [PATCH 08/28] mm: Rename drop_anon_vma to put_anon_vma Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 09/28] mm: Move anon_vma ref out from under CONFIG_KSM Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-09 11:05   ` Mel Gorman
2010-06-07 11:07 ` [PATCH 10/28] mm: Make use of the anon_vma ref count Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-09 13:22   ` Mel Gorman
2010-06-09 13:32     ` Peter Zijlstra [this message]
2010-06-07 11:07 ` [PATCH 11/28] mm: Preemptible mmu_gather Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 12/28] powerpc: " Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 13/28] sparc: " Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 14/28] s390: preemptible mmu_gather Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 15/28] arm: Preemptible mmu_gather Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 16/28] sh: " Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:38   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 17/28] um: " Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 18/28] ia64: " Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 19/28] mm, powerpc: Move the RCU page-table freeing into generic code Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 20/28] sparc64: Kill page table quicklists Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 21/28] sparc64: Use RCU page table freeing Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 22/28] sparc64: Add support for _PAGE_SPECIAL Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 23/28] sparc64: Implement get_user_pages_fast() Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 24/28] lockdep, mutex: Provide mutex_lock_nest_lock Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 25/28] mutex: Provide mutex_is_contended Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 26/28] mm: Convert i_mmap_lock and anon_vma->lock to mutexes Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 27/28] mm: Extended batches for generic mmu_gather Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 28/28] mm: Optimize page_lock_anon_vma() fast-path Peter Zijlstra
2010-06-07 11:07   ` Peter Zijlstra
2010-06-07 13:57 ` [PATCH 00/28] mm: preemptibility -v3 Sam Ravnborg
2010-06-07 15:02   ` Peter Zijlstra
2010-06-07 16:36 ` Andi Kleen
2010-06-07 16:39   ` Peter Zijlstra
2010-06-10  1:45 ` Zhang, Yanmin
2010-06-10  6:52   ` Peter Zijlstra
2010-06-10  6:59     ` Zhang, Yanmin
2010-06-21 10:21       ` Peter Zijlstra
2010-06-24  9:55         ` Peter Zijlstra
2010-06-29  7:40           ` Zhang, Yanmin
2010-06-29  7:48             ` Peter Zijlstra

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