linux-kernel - Re: [RFC PATCH] shrink_dcache

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]

Date:	Tue, 10 Jan 2012 08:33:51 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Al Viro <viro@...iv.linux.org.uk>,
	Dave Chinner <david@...morbit.com>,
	Christoph Hellwig <hch@...radead.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	mgorman@...e.de, gregkh@...e.de, akpm@...ux-foundation.org
Subject: Re: [RFC PATCH] shrink_dcache_parent() deadlock

On Tue, Jan 10, 2012 at 8:22 AM, Miklos Szeredi <miklos@...redi.hu> wrote:
>
> You didn't quite get it right: the flag now needs to be set in
> select_parent() not prune_dcache_sb().

Ahhah.

> I think prune_dcache_sb() doesn't need this logic (although it
> wouldn't hurt either) because that one is called from the slab
> shrinkers and those are protected from being run multiple times in
> parallel, I hope.

Hmm. Even if they are never run in parallel, I think it would be much
nicer to do it in both, just so that there would be a conceptual
consistency of "when we remove the dentry from the LRU list and put it
on our pruning list, we set the bit". That cacheline will be dirty
anyway (due to the list move and getting the dentry lock), so setting
a bit is not expensive - but having odd inconsistent ad-hoc rules is
nasty.

Al?

                        Linus
--
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/