linux-kernel - Re: [PATCH] rwsem-spinlock: let rwsem write lock stealable

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: <20130131211818.GA13195@gmail.com>
Date:	Thu, 31 Jan 2013 22:18:18 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Yuanhan Liu <yuanhan.liu@...ux.intel.com>
Cc:	Michel Lespinasse <walken@...gle.com>,
	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>
Subject: Re: [PATCH] rwsem-spinlock: let rwsem write lock stealable


* Yuanhan Liu <yuanhan.liu@...ux.intel.com> wrote:

> On Thu, Jan 31, 2013 at 02:12:28PM +0100, Ingo Molnar wrote:
> > 
> > * Yuanhan Liu <yuanhan.liu@...ux.intel.com> wrote:
> > 
> > > BTW, mind to tell a nice test case for mmap_sem?
> > 
> > this one was write-hitting on mmap_sem pretty hard, last I 
> > checked:
> > 
> >   http://people.redhat.com/mingo/threaded-mmap-stresstest/
> 
> Thanks!
> 
> Is there any pass condition? I tested a while, at least I 
> found no oops or any noisy from dmesg output. Is that OK?

Yeah, not crashing and not hanging is the expected behavior.

> Well, sometimes, it will quit peacefully. Sometimes it will 
> not. ps -eo 'pid, state,wchan,comm' shows that it is sleeping 
> at futex_wait_queue_me().
> 
> NOTE: this happens both with or w/o this patch. Thus it may 
> not an issue introduced by this patch?

hm, that's unexpected - it's expected to loop infinitely. I have 
a newer version (attached) - is that exiting too?

Maybe this triggers spuriously:

        if (!info->si_addr)
                raise(SIGABRT); /* Allow GDB backtrace */

although then you should see the SIGABRT as an irregular exit 
IIRC.

Thanks,

	Ingo

Download attachment "threaded-mmap-stresstest.tar.gz" of type "application/x-gzip" (3036 bytes)