linux-kernel - Re: [PATCH] fork: dup_mm: init vm stat counters under mmap

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Date:	Wed, 18 Jun 2014 17:22:09 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Vladimir Davydov <vdavydov@...allels.com>
Cc:	akpm@...ux-foundation.org, rientjes@...gle.com, cl@...ux.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fork: dup_mm: init vm stat counters under mmap_sem

On 06/18, Vladimir Davydov wrote:
>
> @@ -365,7 +365,12 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
>  	 */
>  	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
>  
> +	mm->total_vm = oldmm->total_vm;
>  	mm->locked_vm = 0;
> +	mm->pinned_vm = 0;
> +	mm->shared_vm = oldmm->shared_vm;
> +	mm->exec_vm = oldmm->exec_vm;
> +	mm->stack_vm = oldmm->stack_vm;
>  	mm->mmap = NULL;
>  	mm->vmacache_seqnum = 0;
>  	mm->map_count = 0;

I think the patch is fine.


But perhaps this deserves more cleanups, with or without this patch
the initialization does not look consistent. dup_mmap() nullifies
locked_vm/pinned_vm/mmap/map_count while mm_init() clears core_state/
nr_ptes/rss_stat.

Oleg.

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