* [2.6.1-mm2] Badness in futex_wait at kernel/futex.c:509
@ 2004-01-14 5:42 Horacio de Oro
2004-01-14 6:36 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Horacio de Oro @ 2004-01-14 5:42 UTC (permalink / raw)
To: linux-kernel
Hi!
This happen every time I switch from X to console:
Badness in futex_wait at kernel/futex.c:509
Call Trace:
[futex_wait+434/448] futex_wait+0x1b2/0x1c0
[default_wake_function+0/32] default_wake_function+0x0/0x20
[default_wake_function+0/32] default_wake_function+0x0/0x20
[do_futex+112/128] do_futex+0x70/0x80
[sys_futex+292/320] sys_futex+0x124/0x140
[syscall_call+7/11] syscall_call+0x7/0xb
Others messages found in syslog:
Badness in futex_wait at kernel/futex.c:509
Call Trace:
[futex_wait+434/448] futex_wait+0x1b2/0x1c0
[common_interrupt+24/32] common_interrupt+0x18/0x20
[default_wake_function+0/32] default_wake_function+0x0/0x20
[default_wake_function+0/32] default_wake_function+0x0/0x20
[do_futex+112/128] do_futex+0x70/0x80
[sys_futex+292/320] sys_futex+0x124/0x140
[syscall_call+7/11] syscall_call+0x7/0xb
I do not get these messages with 2.6.1.
If more information is needeed, please send me an email
to hgdeoro@yahoo.com
Thanks!
Horacio de Oro
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [2.6.1-mm2] Badness in futex_wait at kernel/futex.c:509
2004-01-14 5:42 [2.6.1-mm2] Badness in futex_wait at kernel/futex.c:509 Horacio de Oro
@ 2004-01-14 6:36 ` Andrew Morton
2004-01-14 22:46 ` Rusty Russell
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2004-01-14 6:36 UTC (permalink / raw)
To: Horacio de Oro; +Cc: linux-kernel, Rusty Russell
Horacio de Oro <hgdeoro@yahoo.com> wrote:
>
> Hi!
>
> This happen every time I switch from X to console:
>
> Badness in futex_wait at kernel/futex.c:509
> Call Trace:
> [futex_wait+434/448] futex_wait+0x1b2/0x1c0
> [default_wake_function+0/32] default_wake_function+0x0/0x20
> [default_wake_function+0/32] default_wake_function+0x0/0x20
> [do_futex+112/128] do_futex+0x70/0x80
> [sys_futex+292/320] sys_futex+0x124/0x140
> [syscall_call+7/11] syscall_call+0x7/0xb
>
/* A spurious wakeup should never happen. */
WARN_ON(!signal_pending(current));
(looks at Rusty)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [2.6.1-mm2] Badness in futex_wait at kernel/futex.c:509
2004-01-14 6:36 ` Andrew Morton
@ 2004-01-14 22:46 ` Rusty Russell
2004-01-15 2:06 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Rusty Russell @ 2004-01-14 22:46 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, Horacio de Oro, mingo
In message <20040113223612.4fe709d9.akpm@osdl.org> you write:
> Horacio de Oro <hgdeoro@yahoo.com> wrote:
> >
> > Hi!
> >
> > This happen every time I switch from X to console:
> >
> > Badness in futex_wait at kernel/futex.c:509
> > Call Trace:
> > [futex_wait+434/448] futex_wait+0x1b2/0x1c0
> > [default_wake_function+0/32] default_wake_function+0x0/0x20
> > [default_wake_function+0/32] default_wake_function+0x0/0x20
> > [do_futex+112/128] do_futex+0x70/0x80
> > [sys_futex+292/320] sys_futex+0x124/0x140
> > [syscall_call+7/11] syscall_call+0x7/0xb
> >
>
> /* A spurious wakeup should never happen. */
> WARN_ON(!signal_pending(current));
>
> (looks at Rusty)
You were the one who said spurious wakeups shouldn't happen 8)
This implies that the console code decided to do wake_up_process() on
us. We returned -EINTR to userspace, but there was no signal, which
is odd.
Anyone have any ideas *why*?
Rusty.
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [2.6.1-mm2] Badness in futex_wait at kernel/futex.c:509
2004-01-14 22:46 ` Rusty Russell
@ 2004-01-15 2:06 ` Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2004-01-15 2:06 UTC (permalink / raw)
To: Rusty Russell; +Cc: linux-kernel, hgdeoro, mingo
Rusty Russell <rusty@rustcorp.com.au> wrote:
>
> In message <20040113223612.4fe709d9.akpm@osdl.org> you write:
> > Horacio de Oro <hgdeoro@yahoo.com> wrote:
> > >
> > > Hi!
> > >
> > > This happen every time I switch from X to console:
> > >
> > > Badness in futex_wait at kernel/futex.c:509
> > > Call Trace:
> > > [futex_wait+434/448] futex_wait+0x1b2/0x1c0
> > > [default_wake_function+0/32] default_wake_function+0x0/0x20
> > > [default_wake_function+0/32] default_wake_function+0x0/0x20
> > > [do_futex+112/128] do_futex+0x70/0x80
> > > [sys_futex+292/320] sys_futex+0x124/0x140
> > > [syscall_call+7/11] syscall_call+0x7/0xb
> > >
> >
> > /* A spurious wakeup should never happen. */
> > WARN_ON(!signal_pending(current));
> >
> > (looks at Rusty)
>
> You were the one who said spurious wakeups shouldn't happen 8)
>
> This implies that the console code decided to do wake_up_process() on
> us. We returned -EINTR to userspace, but there was no signal, which
> is odd.
Well this would seem to imply that this task woke up and ran while it was
still parked on q.waiters, yes?
> Anyone have any ideas *why*?
Nope. This patch should identify the source of the wakeup. Horacio, could
you please add it, see if you get a nice trace? The patch is a bit racy
wrt task exit, but it should hold up for long enough to get a trace.
include/linux/sched.h | 1 +
kernel/futex.c | 5 ++++-
kernel/sched.c | 3 +++
3 files changed, 8 insertions(+), 1 deletion(-)
diff -puN kernel/futex.c~futex-wakeup-debug kernel/futex.c
--- 25/kernel/futex.c~futex-wakeup-debug 2004-01-14 18:01:10.000000000 -0800
+++ 25-akpm/kernel/futex.c 2004-01-14 18:01:10.000000000 -0800
@@ -491,8 +491,11 @@ static int futex_wait(unsigned long uadd
* !list_empty() is safe here without any lock.
* q.lock_ptr != 0 is not safe, because of ordering against wakeup.
*/
- if (likely(!list_empty(&q.list)))
+ if (likely(!list_empty(&q.list))) {
+ current->flags |= PF_FUTEX_DEBUG;
time = schedule_timeout(time);
+ current->flags &= ~PF_FUTEX_DEBUG;
+ }
__set_current_state(TASK_RUNNING);
/*
diff -puN include/linux/sched.h~futex-wakeup-debug include/linux/sched.h
--- 25/include/linux/sched.h~futex-wakeup-debug 2004-01-14 18:01:10.000000000 -0800
+++ 25-akpm/include/linux/sched.h 2004-01-14 18:01:10.000000000 -0800
@@ -500,6 +500,7 @@ do { if (atomic_dec_and_test(&(tsk)->usa
#define PF_SWAPOFF 0x00080000 /* I am in swapoff */
#define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */
#define PF_SYNCWRITE 0x00200000 /* I am doing a sync write */
+#define PF_FUTEX_DEBUG 0x00400000
#ifdef CONFIG_SMP
#define SD_FLAG_NEWIDLE 1 /* Balance when about to become idle */
diff -puN kernel/sched.c~futex-wakeup-debug kernel/sched.c
--- 25/kernel/sched.c~futex-wakeup-debug 2004-01-14 18:01:10.000000000 -0800
+++ 25-akpm/kernel/sched.c 2004-01-14 18:01:10.000000000 -0800
@@ -770,6 +770,9 @@ static int try_to_wake_up(task_t * p, un
}
goto out_activate;
+ if (p->flags & PF_FUTEX_DEBUG)
+ WARN_ON(!signal_pending(p));
+
repeat_lock_task:
task_rq_unlock(rq, &flags);
rq = task_rq_lock(p, &flags);
_
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2004-01-15 2:06 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2004-01-14 5:42 [2.6.1-mm2] Badness in futex_wait at kernel/futex.c:509 Horacio de Oro
2004-01-14 6:36 ` Andrew Morton
2004-01-14 22:46 ` Rusty Russell
2004-01-15 2:06 ` Andrew Morton
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).