From: Alexey Dobriyan <adobriyan@gmail.com>
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Matt Mackall <mpm@selenic.com>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
akpm@linux-foundation.org
Subject: Re: [PATCH] acquire mmap semaphore in pagemap_read.
Date: Thu, 12 Mar 2009 14:45:33 +0300 [thread overview]
Message-ID: <20090312114533.GA2407@x200.localdomain> (raw)
In-Reply-To: <20090312113308.6fe18a93@skybase>
On Thu, Mar 12, 2009 at 11:33:08AM +0100, Martin Schwidefsky wrote:
> --- linux-2.6/fs/proc/task_mmu.c
> +++ linux-2.6-patched/fs/proc/task_mmu.c
> @@ -716,7 +716,9 @@ static ssize_t pagemap_read(struct file
> * user buffer is tracked in "pm", and the walk
> * will stop when we hit the end of the buffer.
> */
> + down_read(&mm->mmap_sem);
> ret = walk_page_range(start_vaddr, end_vaddr, &pagemap_walk);
> + up_read(&mm->mmap_sem);
This will introduce "put_user under mmap_sem" which is deadlockable.
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next prev parent reply other threads:[~2009-03-12 11:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-12 10:33 [PATCH] acquire mmap semaphore in pagemap_read Martin Schwidefsky
2009-03-12 11:45 ` Alexey Dobriyan [this message]
2009-03-12 11:54 ` Martin Schwidefsky
2009-03-12 15:23 ` Matt Mackall
2009-03-12 15:27 ` Martin Schwidefsky
2009-03-12 15:41 ` Brice Goglin
2009-03-12 15:46 ` Martin Schwidefsky
2009-03-12 15:54 ` Martin Schwidefsky
2009-03-17 12:04 ` Martin Schwidefsky
2009-03-17 16:21 ` Matt Mackall
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