linux-kernel - Re: [PATCH] mm: Do not keep page locked during page fault while charging it for memcg

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: <20110622121516.GA28359@infradead.org>
Date:	Wed, 22 Jun 2011 08:15:16 -0400
From:	Christoph Hellwig <hch@...radead.org>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	Michel Lespinasse <walken@...gle.com>
Subject: Re: [PATCH] mm: Do not keep page locked during page fault while
 charging it for memcg

> +
> +			/* We have to drop the page lock here because memcg
> +			 * charging might block for unbound time if memcg oom
> +			 * killer is disabled.
> +			 */
> +			unlock_page(vmf.page);
> +			ret = mem_cgroup_newpage_charge(page, mm, GFP_KERNEL);
> +			lock_page(vmf.page);

This introduces a completely poinless unlock/lock cycle for non-memcg
pagefaults.  Please make sure it only happens when actually needed.

--
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/