Messages in this thread | | | Subject | Re: [PATCH] sched/core: fix illegal RCU from offline CPUs | From | Tetsuo Handa <> | Date | Mon, 13 Jan 2020 17:20:57 +0900 |
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On 2020/01/13 15:30, Qian Cai wrote: >>> - mmdrop(mm); >>> + smp_call_function_single(cpumask_first(cpu_online_mask), >>> + (void (*)(void *))mmdrop, mm, 0); >> >> mmdrop() might sleep, but > > If that is the case, and then the commit e78a7614f387 (“idle: Prevent > late-arriving interrupts from disrupting offline”) is incorrect because it > will disable local irq before calling mmdrop() which will trigger > the might_sleep() warning. Can you prove it?
Is commit 7283094ec3db318e ("kernel, oom: fix potential pgd_lock deadlock from __mmdrop") about only softirq? Is it guaranteed that smp_call_function_single() does not hit such race? Then just my overcareful...
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