Re: linux-next: Tree for Apr 18 [ call-trace: drm | x86 | smp | rcurelated? ]

[Davidlohr Bueso]

On Fri, 2013-04-19 at 15:19 -0400, Rik van Riel wrote:
> On 04/19/2013 02:53 PM, Sedat Dilek wrote:
> > On Fri, Apr 19, 2013 at 6:43 PM, Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >
> >> I tried to switch from SLUB to SLAB...
> >>
> >> ...and also from VIRT_CPU_ACCOUNTING_GEN to TICK_CPU_ACCOUNTING.
> >>
> >> 2x NOPE.
> >>
> >> In one kernel-build I saw in my console...
> >>
> >>       semop(1): encountered an error: Identifier removed

This looks like what Emmanuel was/is running into:
https://lkml.org/lkml/2013/3/30/1

> >>
> >> ...if this says sth. to you.
> >>
> > [ CC folks from below thread ]
> >
> > I have found a thread called "Re: ipc,sem: sysv semaphore scalability"
> > on LKML with a screenshot that shows the same call-trace.
> > I followed it a bit.
> > There is a patch in [3]... unconfirmed.
> >
> > Comments on the rcu read-lock and "sem_lock()" vs "sem_unlock()" from Linus.
> >
> > What's the status of this discussion?
> >
> > - Sedat -
> >
> > [1] https://lkml.org/lkml/2013/3/30/6
> > [2] http://i.imgur.com/uk6gmq1.jpg
> > [3] https://lkml.org/lkml/2013/3/31/12
> > [4] https://lkml.org/lkml/2013/3/31/77
> >
> I am at a conference right now, but when I get
> back I will check linux-next vs. all the fixes from
> the semaphore scalability email thread.

I'm back from the collab. summit, so AFAICT these still need to go in
linux-next:

ipc,sem: untangle RCU locking with find_alloc_undo:
https://lkml.org/lkml/2013/3/28/275

ipc,sem: fix lockdep false positive:
https://lkml.org/lkml/2013/3/29/119

ipc, sem: do not call sem_lock when bogus sma:
https://lkml.org/lkml/2013/3/31/12

Thanks,
Davidlohr

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