| 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
| ||
|
Message-ID: <20070813081441.GA30089@2ka.mipt.ru> Date: Mon, 13 Aug 2007 12:14:41 +0400 From: Evgeniy Polyakov <johnpol@....mipt.ru> To: Daniel Phillips <phillips@...nq.net> Cc: Jens Axboe <jens.axboe@...cle.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org> Subject: Re: Block device throttling [Re: Distributed storage.] On Sun, Aug 12, 2007 at 11:44:00PM -0700, Daniel Phillips (phillips@...nq.net) wrote: > On Sunday 12 August 2007 22:36, I wrote: > > Note! There are two more issues I forgot to mention earlier. > > Oops, and there is also: > > 3) The bio throttle, which is supposed to prevent deadlock, can itself > deadlock. Let me see if I can remember how it goes. > > * generic_make_request puts a bio in flight > * the bio gets past the throttle and initiates network IO > * net calls sk_alloc->alloc_pages->shrink_caches > * shrink_caches submits a bio recursively to our block device > * this bio blocks on the throttle > * net may never get the memory it needs, and we are wedged If system is in such condition, it is already broken - throttle limit must be lowered (next time) not to allow such situation. -- Evgeniy Polyakov - 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/
Powered by blists - more mailing lists