linux-kernel - Re: [PATCH] mm,vmscan: Use accurate values for zone

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.2.20.1510220939310.23718@east.gentwo.org>
Date:	Thu, 22 Oct 2015 09:41:11 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Tejun Heo <htejun@...il.com>
cc:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	mhocko@...nel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	David Rientjes <rientjes@...gle.com>, oleg@...hat.com,
	kwalker@...hat.com, akpm@...ux-foundation.org, hannes@...xchg.org,
	vdavydov@...allels.com, skozina@...hat.com, mgorman@...e.de,
	riel@...hat.com
Subject: Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()
 checks

On Thu, 22 Oct 2015, Tejun Heo wrote:

> The only way to hang the execution for a work item w/ WQ_MEM_RECLAIM
> is to create a cyclic dependency on another work item and keep that
> work item busy wait.  Workqueue thinks that work item is making
> progress as it's running and doesn't schedule the next one.
>
> (I was misremembering here) HIGHPRI originally was implemented
> head-queueing on the same pool followed by immediate execution, so
> could get around cases where this could happen, but that got lost
> while converting it to a separate pool.  I can introduce another flag
> to bypass concurrency management if necessary (it's kinda trivial) but
> busy-waiting cyclic dependency is a pretty unusual thing.
>
> If this is actually a legit busy-waiting cyclic dependency, just let
> me know.

There is no dependency of the vmstat updater on anything.
They can run anytime. If there is a dependency then its created by the
kworker subsystem itself.


--
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/