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McKenney" , "Uladzislau Rezki \(Sony\)" , Michal Hocko Subject: Re: [PATCH] mm: clarify usage of GFP_ATOMIC in !preemptible contexts In-Reply-To: <20200929123010.5137-1-mhocko@kernel.org> References: <20200929123010.5137-1-mhocko@kernel.org> Date: Tue, 29 Sep 2020 21:55:45 +0200 Message-ID: <875z7wjr26.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 29 2020 at 14:30, Michal Hocko wrote: > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 67a0774e080b..2e8370cf60c7 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -238,7 +238,9 @@ struct vm_area_struct; > * %__GFP_FOO flags as necessary. > * > * %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower > - * watermark is applied to allow access to "atomic reserves" > + * watermark is applied to allow access to "atomic reserves". > + * The current implementation doesn't support NMI and few other strict > + * non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT. > * > * %GFP_KERNEL is typical for kernel-internal allocations. The caller requires > * %ZONE_NORMAL or a lower zone for direct access but can direct reclaim. Reviewed-by: Thomas Gleixner