linux-kernel - Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish

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: <20150928144757.GB2881@worktop.programming.kicks-ass.net>
Date:	Mon, 28 Sep 2015 16:47:57 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Jens Axboe <axboe@...com>, Ingo Molnar <mingo@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Chris Mason <clm@...com>, Dave Chinner <david@...morbit.com>,
	Jan Kara <jack@...e.cz>, Josef Bacik <jbacik@...com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Neil Brown <neilb@...e.de>, Christoph Hellwig <hch@....de>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()

On Fri, Sep 18, 2015 at 09:12:38AM -0700, Linus Torvalds wrote:
> 
> So I disagree with your notion that it's a recursion flag. It is
> absolutely nothing of the sort.

OK, agreed. I had it classed under recursion in my head, clearly I
indexed it sloppily. In any case I have a patch that kills off
PREEMPT_ACTIVE entirely.

I just have to clean it up, benchmark, split and write changelogs. But
it should be forthcoming 'soon'. As is, it boots..

> It gets set by preemption - and,
> somewhat illogically, by cond_resched().

I suspect that was done to make cond_resched() (voluntary preemption)
more robust and only have a single preemption path/logic. But all that
was done well before I got involved.
--
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/