Messages in this thread | | | Subject | Re: [PATCH v2 5/6] block: nr_sects_write(): Disable preemption on seqcount write | From | Jens Axboe <> | Date | Thu, 4 Jun 2020 21:22:53 -0600 |
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On 6/3/20 8:49 AM, Ahmed S. Darwish wrote: > For optimized block readers not holding a mutex, the "number of sectors" > 64-bit value is protected from tearing on 32-bit architectures by a > sequence counter. > > Disable preemption before entering that sequence counter's write side > critical section. Otherwise, the read side can preempt the write side > section and spin for the entire scheduler tick. If the reader belongs to > a real-time scheduling class, it can spin forever and the kernel will > livelock.
Applied, thanks.
-- Jens Axboe
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