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| author |   Oleg Nesterov <oleg@redhat.com> | 2014-10-05 22:23:22 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2014-10-28 10:46:05 +0100 |
| commit | 009f60e2763568cdcd75bd1cf360c7c7165e2e60 (patch) | |
| tree | 190e6cb5857bd0c2788939fe4004a128e655ec49 /arch | |
| parent | sched/fair: Fix division by zero sysctl_numa_balancing_scan_size (diff) | |
| download | wireguard-linux-009f60e2763568cdcd75bd1cf360c7c7165e2e60.tar.xz wireguard-linux-009f60e2763568cdcd75bd1cf360c7c7165e2e60.zip | |
sched: stop the unbound recursion in preempt_schedule_context()
preempt_schedule_context() does preempt_enable_notrace() at the end
and this can call the same function again; exception_exit() is heavy
and it is quite possible that need-resched is true again.
1. Change this code to dec preempt_count() and check need_resched()
by hand.
2. As Linus suggested, we can use the PREEMPT_ACTIVE bit and avoid
the enable/disable dance around __schedule(). But in this case
we need to move into sched/core.c.
3. Cosmetic, but x86 forgets to declare this function. This doesn't
really matter because it is only called by asm helpers, still it
make sense to add the declaration into asm/preempt.h to match
preempt_schedule().
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20141005202322.GB27962@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/preempt.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index 7024c12f7bfe..400873450e33 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -105,6 +105,7 @@ static __always_inline bool should_resched(void) # ifdef CONFIG_CONTEXT_TRACKING extern asmlinkage void ___preempt_schedule_context(void); # define __preempt_schedule_context() asm ("call ___preempt_schedule_context") + extern asmlinkage void preempt_schedule_context(void); # endif #endif |