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[109.81.31.43]) by smtp.gmail.com with UTF8SMTPSA id a640c23a62f3a-b07b3347b6fsm990538866b.111.2025.09.15.10.16.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Sep 2025 10:16:51 -0700 (PDT) Date: Mon, 15 Sep 2025 19:16:50 +0200 From: Michal Hocko To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Andrew Morton , Baoquan He , LKML Subject: Re: [PATCH v2 09/10] mm: Skip might_alloc() warnings when PF_MEMALLOC is set Message-ID: References: <20250915134041.151462-1-urezki@gmail.com> <20250915134041.151462-10-urezki@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250915134041.151462-10-urezki@gmail.com> On Mon 15-09-25 15:40:39, Uladzislau Rezki wrote: > might_alloc() catches invalid blocking allocations in contexts > where sleeping is not allowed. > > However when PF_MEMALLOC is set, the page allocator already skips > reclaim and other blocking paths. In such cases, a blocking gfp_mask > does not actually lead to blocking, so triggering might_alloc() splats > is misleading. > > Adjust might_alloc() to skip warnings when the current task has > PF_MEMALLOC set, matching the allocator's actual blocking behaviour. > > Signed-off-by: Uladzislau Rezki (Sony) I would probably just bail out early for PF_MEMALLOC to not meddle with might_sleep_if condition as it seems to read better but I do not insist. Acked-by: Michal Hocko Thanks > --- > include/linux/sched/mm.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h > index 2201da0afecc..dc2d3cab32ef 100644 > --- a/include/linux/sched/mm.h > +++ b/include/linux/sched/mm.h > @@ -318,7 +318,8 @@ static inline void might_alloc(gfp_t gfp_mask) > fs_reclaim_acquire(gfp_mask); > fs_reclaim_release(gfp_mask); > > - might_sleep_if(gfpflags_allow_blocking(gfp_mask)); > + might_sleep_if(gfpflags_allow_blocking(gfp_mask) && > + !(current->flags & PF_MEMALLOC)); > } > > /** > -- > 2.47.3 -- Michal Hocko SUSE Labs