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Groups > linux.kernel > #1645728
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure |
| Date | 2017-05-19 18:10 +0200 |
| Message-ID | <tISDw-4BS-35@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <tIom6-7a7-7@gated-at.bofh.it> <tIoP7-7E3-7@gated-at.bofh.it> <tIp8u-7LV-35@gated-at.bofh.it> <tIp8u-7LV-33@gated-at.bofh.it> <tISka-4bg-19@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, May 19, 2017 at 05:48:50PM +0200, Peter Zijlstra wrote:
> Markus reported that the glibc/nptl/tst-robustpi8 test was failing after
> commit:
>
> cfafcd117da0 ("futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()")
>
> Much tracing later I managed to catch the culprit:
>
> ld-linux-x86-64-2161 [019] .... 410.760971: SyS_futex: 00007ffbeb76b028: 80000875 op=FUTEX_LOCK_PI
> ld-linux-x86-64-2161 [019] ...1 410.760972: lock_pi_update_atomic: 00007ffbeb76b028: curval=80000875 uval=80000875 newval=80000875 ret=0
> ld-linux-x86-64-2165 [011] .... 410.760978: SyS_futex: 00007ffbeb76b028: 80000875 op=FUTEX_UNLOCK_PI
> ld-linux-x86-64-2165 [011] d..1 410.760979: do_futex: 00007ffbeb76b028: curval=80000875 uval=80000875 newval=80000871 ret=0
> ld-linux-x86-64-2165 [011] .... 410.760980: SyS_futex: 00007ffbeb76b028: 80000871 ret=0000
> ld-linux-x86-64-2161 [019] .... 410.760980: SyS_futex: 00007ffbeb76b028: 80000871 ret=ETIMEDOUT
The above trace continues like:
ld-linux-x86-64-2164 [006] .... 410.762336: SyS_futex: 00007ffbeb76b028: 80000871 op=FUTEX_LOCK_PI
ld-linux-x86-64-2164 [006] ...1 410.762337: lock_pi_update_atomic: 00007ffbeb76b028: curval=80000871 uval=80000871 newval=80000871 ret=0
ld-linux-x86-64-2164 [006] .... 410.762347: SyS_futex: 00007ffbeb76b028: 80000871 ret=ETIMEDOUT
ld-linux-x86-64-2161 [019] .... 410.762521: SyS_futex: 00007ffbeb76b028: 80000871 op=FUTEX_LOCK_PI
ld-linux-x86-64-2161 [019] .... 410.762522: SyS_futex: 00007ffbeb76b028: 80000871 ret=EDEADLK
And every subsequent attempt by 2161 will (obviously) return EDEADLK.
Now since the test explicitly tracks the lock state[] and
pthread_mutex_*lock() return values this _should_ have triggered one of
the printf()'s, but I never saw any of those.
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commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Markus Trippelsdorf <markus@trippelsdorf.de> - 2017-05-17 19:40 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Florian Weimer <fweimer@redhat.com> - 2017-05-17 20:00 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 08:50 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 09:00 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 09:50 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Markus Trippelsdorf <markus@trippelsdorf.de> - 2017-05-18 10:10 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 10:20 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Florian Weimer <fweimer@redhat.com> - 2017-05-18 10:20 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Florian Weimer <fweimer@redhat.com> - 2017-05-18 10:40 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 10:50 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Florian Weimer <fweimer@redhat.com> - 2017-05-18 10:50 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 13:50 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 14:40 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-19 17:50 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-19 18:10 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Markus Trippelsdorf <markus@trippelsdorf.de> - 2017-05-19 19:40 +0200
[tip:locking/urgent] futex,rt_mutex: Fix rt_mutex_cleanup_proxy_lock() tip-bot for Peter Zijlstra <tipbot@zytor.com> - 2017-05-22 22:10 +0200
Re: commit cfafcd117 "futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()" causes glibc nptl/tst-robustpi8 failure Peter Zijlstra <peterz@infradead.org> - 2017-05-18 10:40 +0200
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