diff options
| author | Peter Zijlstra | 2021-10-18 16:41:05 +0200 |
|---|---|---|
| committer | Peter Zijlstra | 2021-10-22 15:32:46 +0200 |
| commit | 96611c26dc351c33f73b48756a9feacc109e5bab (patch) | |
| tree | d1feeaf18f00f6777dceb73620de7938c94f2a13 /kernel/smp.c | |
| parent | 09089db79859cbccccd8df95b034f36f7027efa6 (diff) | |
sched: Improve wake_up_all_idle_cpus() take #2
As reported by syzbot and experienced by Pavel, using cpus_read_lock()
in wake_up_all_idle_cpus() generates lock inversion (against mmap_sem
and possibly others).
Instead, shrink the preempt disable region by iterating all CPUs and
checking the online status for each individual CPU while having
preemption disabled.
Fixes: 8850cb663b5c ("sched: Simplify wake_up_*idle*()")
Reported-by: syzbot+d5b23b18d2f4feae8a67@syzkaller.appspotmail.com
Reported-by: Pavel Machek <pavel@ucw.cz>
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
Diffstat (limited to 'kernel/smp.c')
| -rw-r--r-- | kernel/smp.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index ad0b68a3a3d3..01a7c1706a58 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -1170,14 +1170,12 @@ void wake_up_all_idle_cpus(void) { int cpu; - cpus_read_lock(); - for_each_online_cpu(cpu) { - if (cpu == raw_smp_processor_id()) - continue; - - wake_up_if_idle(cpu); + for_each_possible_cpu(cpu) { + preempt_disable(); + if (cpu != smp_processor_id() && cpu_online(cpu)) + wake_up_if_idle(cpu); + preempt_enable(); } - cpus_read_unlock(); } EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); |