linux-kernel - Re: [PATCH 0/5] (Was: procfs: silence lockdep warning about read vs. exec seq

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Message-ID: <20140804092043.GA13940@node.dhcp.inet.fi>
Date:	Mon, 4 Aug 2014 12:20:43 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	David Howells <dhowells@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Sasha Levin <levinsasha928@...il.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	"David S. Miller" <davem@...emloft.net>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH 0/5] (Was: procfs: silence lockdep warning about read vs.
 exec seq_file)

On Sun, Aug 03, 2014 at 11:18:43PM +0200, Oleg Nesterov wrote:
> On 08/03, Oleg Nesterov wrote:
> >
> > The question is, why m_start() calls mm_access(). This is not even
> > strictly correct if the task execs between m_stop() + m_start().
> >
> > Can't we do something like below? The patch is obviously horrible and
> > incomplete, just to explain what I meant. Basically this is what
> > proc_mem_operations does.
> 
> Absolutely untested, only for review.
> 
> What do you all think?

Look good. And works for me.

> Sure, with this change you can't open (say) /proc/pid/maps, and read the
> new mappings after exec. But hopefully this is fine? And again, this
> matches /proc/pid/mem.
> 
> lock_trace() users need another fix.

task_nommu.c need to be covered too, I believe.

-- 
 Kirill A. Shutemov
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