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SubjectRe: ipc,sem: sysv semaphore scalability
On 03/29/2013 03:01 PM, Dave Jones wrote:
> On Tue, Mar 26, 2013 at 12:43:09PM -0700, Andrew Morton wrote:
> > On Tue, 26 Mar 2013 15:28:52 -0400 Dave Jones <davej@redhat.com> wrote:
> >
> > > On Thu, Mar 21, 2013 at 02:10:58PM -0700, Andrew Morton wrote:
> > >
> > > > Whichever way we go, we should get a wiggle on - this has been hanging
> > > > around for too long. Dave, do you have time to determine whether
> > > > reverting 88b9e456b1649722673ff ("ipc: don't allocate a copy larger
> > > > than max") fixes things up?
> > >
> > > Ok, with that reverted it's been grinding away for a few hours without incident.
> > > Normally I see the oops within a minute or so.
> > >
> >
> > OK, thanks, I queued a revert:
> >
> > From: Andrew Morton <akpm@linux-foundation.org>
> > Subject: revert "ipc: don't allocate a copy larger than max"
> >
> > Revert 88b9e456b164. Dave has confirmed that this was causing oopses
> > during trinity testing.
>
> I owe Peter an apology. I just hit it again with that backed out.
> Andrew, might as well drop that revert.
>
> BUG: unable to handle kernel NULL pointer dereference at 000000000000000f
> IP: [<ffffffff812c24ca>] testmsg.isra.5+0x1a/0x60
> [...snip...]
>
> I think I wasn't seeing that this last week because I had inadvertantly disabled DEBUG_PAGEALLOC
>
> and.. we're back to square one.
>
> Dave

Andrew,

I just realized you're still carrying

commit 4bea54c91bcc5451f237e6b721b0b35eccd01d17
Author: Andrew Morton <akpm@linux-foundation.org>
Date: Fri Apr 26 10:55:12 2013 +1000

revert "ipc: don't allocate a copy larger than max"

Revert 88b9e456b164. Dave has confirmed that this was causing oopses
during trinity testing.

Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Reported-by: Dave Jones <davej@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Please drop.

As quoted above, the testing on mainline that attributed
the observed oops to the reverted patch was due to a config
error.

As Linus pointed out below, this patch fixes real bugs.

On 04/02/2013 03:53 PM, Sasha Levin wrote:
> On 04/02/2013 01:52 PM, Linus Torvalds wrote:
>> On Tue, Apr 2, 2013 at 9:08 AM, Sasha Levin <sasha.levin@oracle.com> wrote:
>>>
>>> By just playing with the 'msgsz' parameter with MSG_COPY set.
>>
>> Hmm. Looking closer, I suspect you're testing without commit
>> 88b9e456b164 ("ipc: don't allocate a copy larger than max"). That
>> should limit the size passed in to prepare_copy -> load_copy to
>> msg_ctlmax.
>
> That commit has a revert in the -next trees, do we need a revert
> of the revert?
>
> commit ff6577a3e714ccae02d4400e989762c19c37b0b3
> Author: Andrew Morton <akpm@linux-foundation.org>
> Date: Wed Mar 27 10:24:02 2013 +1100
>
> revert "ipc: don't allocate a copy larger than max"
>
> Revert 88b9e456b164. Dave has confirmed that this was causing oopses
> during trinity testing.
>
> Cc: Peter Hurley <peter@hurleysoftware.com>
> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
> Reported-by: Dave Jones <davej@redhat.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>


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