Messages in this thread | | | Subject | Re: [PATCH] mm: clarify usage of GFP_ATOMIC in !preemptible contexts | From | David Hildenbrand <> | Date | Tue, 29 Sep 2020 15:29:59 +0200 |
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On 29.09.20 14:30, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > There is a general understanding that GFP_ATOMIC/GFP_NOWAIT are > to be used from atomic contexts. E.g. from within a spin lock or from > the IRQ context. This is correct but there are some atomic contexts > where the above doesn't hold. One of them would be an NMI context. > Page allocator has never supported that and the general fear of this > context didn't let anybody to actually even try to use the allocator > there. Good, but let's be more specific about that. > > Another such a context, and that is where people seem to be more daring, > is raw_spin_lock. Mostly because it simply resembles regular spin lock > which is supported by the allocator and there is not any implementation > difference with !RT kernels in the first place. Be explicit that such > a context is not supported by the allocator. The underlying reason is > that zone->lock would have to become raw_spin_lock as well and that has > turned out to be a problem for RT > (http://lkml.kernel.org/r/87mu305c1w.fsf@nanos.tec.linutronix.de).
Interesting
Reviewed-by: David Hildenbrand <david@redhat.com>
-- Thanks,
David / dhildenb
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