linux-kernel - Re: [PATCH] fs: fput() can be called from interrupt context

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:	Sat, 14 Mar 2009 07:32:19 -0700 (PDT)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Trond Myklebust <trond.myklebust@....uio.no>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Dumazet <dada1@...mosbay.com>,
	Jeff Moyer <jmoyer@...hat.com>, Avi Kivity <avi@...hat.com>,
	linux-aio <linux-aio@...ck.org>, zach.brown@...cle.com,
	Benjamin LaHaise <bcrl@...ck.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [PATCH] fs: fput() can be called from interrupt context

On Sat, 14 Mar 2009, Trond Myklebust wrote:

> > Did I miss something? This wouldn't be (eventually) on keventd shoulders, 
> > but on aio work queue (aio_wq).
> > I guess we could do the same optimization we're already doing for ki_filp, 
> > for ki_eventfd ...
> 
> Last I checked, a call to schedule_work(&fddef->wq) would still run
> fd_defer_queue() under keventd.

Oh, you were commenting about Eric's patch-set. I thought you were talking 
about the current status (that my reply to Andrew was hinting to), and was 
wondering for a while from where fd_defer_queue() came from.

> That said, even if you were to run it under aio_wq, the argument remains
> the same: do you really want to add potentially long lasting sleeps onto
> a work queue that was designed to service fast i/o requests?

No, and if you roll back, you couldn't miss to notice that mine was a 
question about the f_count direct manipulation/optimization. We can do the 
same optimization for eventfd, although both will fall in the aio kthread 
in any case, if we're holding the last insteance of the file* (that I 
guess we can consider an unlikely case).
Dunno how worth it could be adding a new NCPU*thread(s) just to handle 
delayed fputs.

- Davide

--
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/