linux-kernel - Re: [PATCH v2 5/7] fs/proc/task_mmu.c: simplify the vma

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Date:	Wed, 6 Aug 2014 13:12:45 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	David Howells <dhowells@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Sasha Levin <levinsasha928@...il.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/7] fs/proc/task_mmu.c: simplify the vma_stop() logic

On Tue, Aug 05, 2014 at 09:46:59PM +0200, Oleg Nesterov wrote:
> m_start() drops ->mmap_sem and does mmput() if it retuns vsyscall
> vma. This is because in this case m_stop()->vma_stop() obviously
> can't use gate_vma->vm_mm.
> 
> Now that we have proc_maps_private->mm we can simplify this logic:
> 
>   - Change m_start() to return with ->mmap_sem held unless it returns
>     IS_ERR_OR_NULL().
> 
>   - Change vma_stop() to use priv->mm and avoid the ugly vma checks,
>     this makes "vm_area_struct *vma" unnecessary.
> 
>   - This also allows m_start() to use vm_stop().
> 
>   - Cleanup m_next() to follow the new locking rule.
> 
>     Note: m_stop() looks very ugly, and this temporary uglifies it
>     even more. Fixed by the next change.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov
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