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Sun, 28 Apr 2024 01:10:40 -0700 (PDT) Received: from [2620:0:1008:15:46db:4823:ceac:2ea3] ([2620:0:1008:15:46db:4823:ceac:2ea3]) by smtp.gmail.com with ESMTPSA id im15-20020a170902bb0f00b001e45572a253sm18481547plb.14.2024.04.28.01.10.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 Apr 2024 01:10:40 -0700 (PDT) Date: Sun, 28 Apr 2024 01:10:39 -0700 (PDT) From: David Rientjes To: linke li cc: xujianhao01@gmail.com, Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slub: mark racy access on slab->freelist In-Reply-To: Message-ID: <1096134d-df6f-185d-240f-8a774d66f98f@google.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Stat-Signature: d371uis4yt7ogjhf5efoagcep51yaec3 X-Rspamd-Queue-Id: 3C4864000F X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1714291842-105715 X-HE-Meta: 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 YF5b69sc 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000343, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 27 Apr 2024, linke li wrote: > In deactivate_slab(), slab->freelist can be changed concurrently. Mark > data race on slab->freelist as benign using READ_ONCE. > > This patch is aimed at reducing the number of benign races reported by > KCSAN in order to focus future debugging effort on harmful races. > Thanks! Do you have a data race report to copy+paste into the commit description so people can search for it if they stumble across the same thing? > Signed-off-by: linke li > --- > mm/slub.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 0d700f6ca547..bb0e05a321e9 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2813,7 +2813,7 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab, > struct slab new; > struct slab old; > > - if (slab->freelist) { > + if (READ_ONCE(slab->freelist)) { > stat(s, DEACTIVATE_REMOTE_FREES); > tail = DEACTIVATE_TO_TAIL; > } > -- > 2.39.3 (Apple Git-146) > >