From: Al Viro <viro@ZenIV.linux.org.uk>
To: Stephen Wilson <wilsons@start.ca>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Roland McGrath <roland@redhat.com>,
Matt Mackall <mpm@selenic.com>,
David Rientjes <rientjes@google.com>,
Nick Piggin <npiggin@kernel.dk>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mel@csn.ul.ie>, Ingo Molnar <mingo@elte.hu>,
Michel Lespinasse <walken@google.com>,
Hugh Dickins <hughd@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] enable writing to /proc/pid/mem
Date: Wed, 9 Mar 2011 02:33:04 +0000 [thread overview]
Message-ID: <20110309023303.GZ22723@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20110309021524.GA4838@fibrous.localdomain>
On Tue, Mar 08, 2011 at 09:15:25PM -0500, Stephen Wilson wrote:
> I think we could also remove the intermediate copy in both mem_read() and
> mem_write() as well, but I think such optimizations could be left for
> follow on patches.
How? We do copy_.._user() in there; it can trigger page faults and
that's not something you want while holding mmap_sem on some mm.
Looks like a deadlock country... So we can't do that from inside
access_process_vm() or its analogs, which means buffering in caller.
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Stephen Wilson <wilsons@start.ca>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Roland McGrath <roland@redhat.com>,
Matt Mackall <mpm@selenic.com>,
David Rientjes <rientjes@google.com>,
Nick Piggin <npiggin@kernel.dk>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mel@csn.ul.ie>, Ingo Molnar <mingo@elte.hu>,
Michel Lespinasse <walken@google.com>,
Hugh Dickins <hughd@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] enable writing to /proc/pid/mem
Date: Wed, 9 Mar 2011 02:33:04 +0000 [thread overview]
Message-ID: <20110309023303.GZ22723@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20110309021524.GA4838@fibrous.localdomain>
On Tue, Mar 08, 2011 at 09:15:25PM -0500, Stephen Wilson wrote:
> I think we could also remove the intermediate copy in both mem_read() and
> mem_write() as well, but I think such optimizations could be left for
> follow on patches.
How? We do copy_.._user() in there; it can trigger page faults and
that's not something you want while holding mmap_sem on some mm.
Looks like a deadlock country... So we can't do that from inside
access_process_vm() or its analogs, which means buffering in caller.
--
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next prev parent reply other threads:[~2011-03-09 2:33 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-09 0:42 [PATCH 0/6] enable writing to /proc/pid/mem Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 0:42 ` [PATCH 1/6] mm: use mm_struct to resolve gate vma's in __get_user_pages Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 5:19 ` KOSAKI Motohiro
2011-03-09 5:19 ` KOSAKI Motohiro
2011-03-09 6:06 ` Al Viro
2011-03-09 6:06 ` Al Viro
2011-03-09 12:38 ` Stephen Wilson
2011-03-09 12:38 ` Stephen Wilson
2011-03-09 0:42 ` [PATCH 2/6] mm: factor out main logic of access_process_vm Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 0:42 ` [PATCH 3/6] mm: implement access_remote_vm Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 0:42 ` [PATCH 4/6] proc: disable mem_write after exec Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 5:22 ` KOSAKI Motohiro
2011-03-09 5:22 ` KOSAKI Motohiro
2011-03-09 0:42 ` [PATCH 5/6] proc: make check_mem_permission() return an mm_struct on success Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 6:20 ` KOSAKI Motohiro
2011-03-09 6:20 ` KOSAKI Motohiro
2011-03-09 0:42 ` [PATCH 6/6] proc: enable writing to /proc/pid/mem Stephen Wilson
2011-03-09 0:42 ` Stephen Wilson
2011-03-09 1:30 ` [PATCH 0/6] " Al Viro
2011-03-09 1:30 ` Al Viro
2011-03-09 2:15 ` Stephen Wilson
2011-03-09 2:15 ` Stephen Wilson
2011-03-09 2:33 ` Al Viro [this message]
2011-03-09 2:33 ` Al Viro
2011-03-09 2:47 ` Stephen Wilson
2011-03-09 2:47 ` Stephen Wilson
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