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Sun, 07 Apr 2024 14:06:21 -0700 (PDT) Date: Sun, 7 Apr 2024 14:06:19 -0700 (PDT) From: David Rientjes To: Sangyun Kim cc: linux-mm@kvack.org, Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Hyunmin Lee , Jeungwoo Yoo , Gwan-gyeong Mun Subject: Re: [PATCH] mm/slub: remove duplicate initialization for early_kmem_cache_node_alloc() In-Reply-To: <20240406074449.563704-1-sangyun.kim@snu.ac.kr> Message-ID: <5bfe9c1c-7620-b7fd-b5fb-c481e7dfa5e7@google.com> References: <20240406074449.563704-1-sangyun.kim@snu.ac.kr> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 605C7100005 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: fqqxswoxhnmkw4gbs1w7i4t1ygp1iuau X-HE-Tag: 1712523983-469071 X-HE-Meta: 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 LBafC8tq VkdGyvxH23glb6yb1qryomDxIl/kdr79zeT9XHdkpTF3cM+JvEH9GaTecNIoCjXg2DEQS9biPyN7pMAy0k03e3PWIfKw84DMGl4I/z/APGh2EPKY9tn/+BFQHJD/SRfYJEg2913N9C31t60NHpk7GZwCkpgcvfwgUL2V4IpTxNUhJMxP8kkKeGGcpXndWLOPn9VyH5OpGTznaahcMM/2RmNE8qjgBZ2zWpPhVd032tR8bO+cfOXMj+mADVZUt/N1jeZW6ZtIkCdiKtMwLht7MT31ezD7fbkKRqvUZh+7VurAFEnBn8smVYcfO5NB/VTHGFuLDJeBLpPgy92FuPDTBbN07VyQeFsSYkAqalqqbauCIOaapKE54VGaBjAjXtblKsKxduDnouvAvddHl9BFYnQa8D5whOg7irTi3Jua6IYMV4TsK9Qq97jsZK/f3qTgZleT+9W2NAw8ufObeB9COHVThhtoYd1ODVZesEKjgILiFpKiw5DmDYMTO4GSDR05zpTPG864QvJBj8DdDchOt8QNoRKwaPCibk8R0R0r1Q4CyUy93j72nrZd+goDPNe1ngCqd 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: List-Subscribe: List-Unsubscribe: On Sat, 6 Apr 2024, Sangyun Kim wrote: > The struct track for every object in a new slab is already set up by > new_slab(), > so remove the duplicate initialization in early_kmem_cache_node_alloc(). > > Signed-off-by: Sangyun Kim > > Co-developed-by: Hyunmin Lee > Signed-off-by: Hyunmin Lee > > Co-developed-by: Jeungwoo Yoo > Signed-off-by: Jeungwoo Yoo > > Cc: Gwan-gyeong Mun > --- > mm/slub.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 0dfc0c18a78b..5ffe46843b36 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -4938,7 +4938,6 @@ static void early_kmem_cache_node_alloc(int node) > BUG_ON(!n); > #ifdef CONFIG_SLUB_DEBUG > init_object(kmem_cache_node, n, SLUB_RED_ACTIVE); > - init_tracking(kmem_cache_node, n); > #endif > n = kasan_slab_alloc(kmem_cache_node, n, GFP_KERNEL, false); > slab->freelist = get_freepointer(kmem_cache_node, n); I think this is technically safe based on the current implementation because, as you said, allocate_slab() takes care of this for SLAB_STORE_USER. What user observable effect does this have given it would only make a difference when slab_state == DOWN?