Messages in this thread | | | Date | Tue, 18 Apr 2017 15:46:31 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH linux-4.1.y] sched/wait: Fix signal handling in bit wait helpers |
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Just curious, any particular reason you want to backport this patch?
because nobody understands why it actually helped.
and please note that this patch is buggy, fixed by dfd01f0260 "sched/wait: Fix the signal handling fix"
Oleg.
On 04/12, Florian Fainelli wrote: > > From: Peter Zijlstra <peterz@infradead.org> > > [ Upstream commit 68985633bccb6066bf1803e316fbc6c1f5b796d6 ] > > Vladimir reported getting RCU stall warnings and bisected it back to > commit: > > 743162013d40 ("sched: Remove proliferation of wait_on_bit() action functions") > > That commit inadvertently reversed the calls to schedule() and signal_pending(), > thereby not handling the case where the signal receives while we sleep. > > Reported-by: Vladimir Murzin <vladimir.murzin@arm.com> > Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Mike Galbraith <efault@gmx.de> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: mark.rutland@arm.com > Cc: neilb@suse.de > Cc: oleg@redhat.com > Fixes: 743162013d40 ("sched: Remove proliferation of wait_on_bit() action functions") > Fixes: cbbce8220949 ("SCHED: add some "wait..on_bit...timeout()" interfaces.") > Link: http://lkml.kernel.org/r/20151201130404.GL3816@twins.programming.kicks-ass.net > Signed-off-by: Ingo Molnar <mingo@kernel.org> > --- > kernel/sched/wait.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c > index 852143a79f36..e0bb7e6c4fb0 100644 > --- a/kernel/sched/wait.c > +++ b/kernel/sched/wait.c > @@ -583,18 +583,18 @@ EXPORT_SYMBOL(wake_up_atomic_t); > > __sched int bit_wait(struct wait_bit_key *word) > { > - if (signal_pending_state(current->state, current)) > - return 1; > schedule(); > + if (signal_pending(current)) > + return -EINTR; > return 0; > } > EXPORT_SYMBOL(bit_wait); > > __sched int bit_wait_io(struct wait_bit_key *word) > { > - if (signal_pending_state(current->state, current)) > - return 1; > io_schedule(); > + if (signal_pending(current)) > + return -EINTR; > return 0; > } > EXPORT_SYMBOL(bit_wait_io); > @@ -602,11 +602,11 @@ EXPORT_SYMBOL(bit_wait_io); > __sched int bit_wait_timeout(struct wait_bit_key *word) > { > unsigned long now = ACCESS_ONCE(jiffies); > - if (signal_pending_state(current->state, current)) > - return 1; > if (time_after_eq(now, word->timeout)) > return -EAGAIN; > schedule_timeout(word->timeout - now); > + if (signal_pending(current)) > + return -EINTR; > return 0; > } > EXPORT_SYMBOL_GPL(bit_wait_timeout); > @@ -614,11 +614,11 @@ EXPORT_SYMBOL_GPL(bit_wait_timeout); > __sched int bit_wait_io_timeout(struct wait_bit_key *word) > { > unsigned long now = ACCESS_ONCE(jiffies); > - if (signal_pending_state(current->state, current)) > - return 1; > if (time_after_eq(now, word->timeout)) > return -EAGAIN; > io_schedule_timeout(word->timeout - now); > + if (signal_pending(current)) > + return -EINTR; > return 0; > } > EXPORT_SYMBOL_GPL(bit_wait_io_timeout); > -- > 2.12.1 >
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