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: <55FC1E72.3040500@fb.com>
Date:	Fri, 18 Sep 2015 08:23:46 -0600
From:	Jens Axboe <axboe@...com>
To:	Chris Mason <clm@...com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	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 09/18/2015 07:16 AM, Chris Mason wrote:
> On Thu, Sep 17, 2015 at 11:04:03PM -0700, Linus Torvalds wrote:
>> On Thu, Sep 17, 2015 at 10:40 PM, Dave Chinner <david@...morbit.com> wrote:
>>>
>>> Ok, makes sense - the plug is not being flushed as we switch away,
>>> but Chris' patch makes it do that.
>>
>> Yup.
>
> Huh, that does make much more sense, thanks Linus.  I'm wondering where
> else I've assumed that cond_resched() unplugged.
>
>>
>> And I actually think Chris' patch is better than the one I sent out
>> (but maybe the scheduler people should take a look at the behavior of
>> cond_resched()), I just wanted you to test that to verify the
>> behavior.

It makes no sense for preemption schedule to NOT unplug, the fact that 
it doesn't is news to me as well. It was never the intent of the 
unplug-on-schedule to NOT unplug for certain schedule out events, that 
seems like very odd behavior.

-- 
Jens Axboe

--
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/