linux-kernel - Re: [PATCH 1/6] Revert "mm: mempolicy: Let vma_merge and vma_split handle vma->vm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.00.1205301414020.31768@router.home>
Date:	Wed, 30 May 2012 14:17:29 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Andrew Morton <akpm@...gle.com>, Dave Jones <davej@...hat.com>,
	Mel Gorman <mgorman@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	stable@...r.kernel.org, hughd@...gle.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [PATCH 1/6] Revert "mm: mempolicy: Let vma_merge and vma_split
 handle vma->vm_policy linkages"

On Wed, 30 May 2012, kosaki.motohiro@...il.com wrote:

> From: KOSAKI Motohiro <kosaki.motohiro@...il.com>
>
> commit 05f144a0d5 removed vma->vm_policy updates code and it is a purpose of
> mbind_range(). Now, mbind_range() is virtually no-op. no-op function don't
> makes any bugs, I agree. but maybe it is not right fix.

I dont really understand the changelog. But to restore the policy_vma() is
the right thing to do since there are potential multiple use cases where
we want to apply a policy to a vma.

Proposed new changelog:

Commit 05f144a0d5 folded policy_vma() into mbind_range(). There are
other use cases of policy_vma(*) though and so revert a piece of
that commit in order to have a policy_vma() function again.

> @@ -655,23 +676,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
>  			if (err)
>  				goto out;
>  		}
> -
> -		/*
> -		 * Apply policy to a single VMA. The reference counting of
> -		 * policy for vma_policy linkages has already been handled by
> -		 * vma_merge and split_vma as necessary. If this is a shared
> -		 * policy then ->set_policy will increment the reference count
> -		 * for an sp node.
> -		 */

You are dropping the nice comments by Mel that explain the refcounting.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/