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Thu, 15 Jan 2026 13:53:37 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id kNb/AmHxaGkrRQAAD6G6ig (envelope-from ); Thu, 15 Jan 2026 13:53:37 +0000 Message-ID: <3aa7a303-677d-4ef5-8df1-b3c0fdfcc787@suse.cz> Date: Thu, 15 Jan 2026 14:53:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v2 09/20] slab: remove cpu (partial) slabs usage from allocation paths Content-Language: en-US To: Hao Li Cc: Harry Yoo , Petr Tesarik , Christoph Lameter , David Rientjes , Roman Gushchin , Andrew Morton , Uladzislau Rezki , "Liam R. Howlett" , Suren Baghdasaryan , Sebastian Andrzej Siewior , Alexei Starovoitov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, bpf@vger.kernel.org, kasan-dev@googlegroups.com References: <20260112-sheaves-for-all-v2-0-98225cfb50cf@suse.cz> <20260112-sheaves-for-all-v2-9-98225cfb50cf@suse.cz> <3k4wy7gavxczpqn63jt66423fqa3wvdztigvbmejbvcpbr7ld2@fbylldpeuvgi> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <3k4wy7gavxczpqn63jt66423fqa3wvdztigvbmejbvcpbr7ld2@fbylldpeuvgi> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 1fgxnnuujjhk7xyfui85f6ke6ere8m65 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: BDF3D180006 X-Rspam-User: X-HE-Tag: 1768485218-792561 X-HE-Meta: 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 w7hKZ9Eg 9/uYIBdSg5ofI+b8DCbYdr03XpJG+RcdGU0/QyIb0aWgWbU4oZDaK+C99dbu7E3hDTBTeDuIcG9Udzsp/rNh9WEf9b7fQEA4FAHfgAxHoPs/NjnF4YCuM0a1Qdv9g+lWg9zwOLEFu+3vg2/EdqR7F/dR4DNx7ALzzeUruXp31CmuHSwVmu0V6Hkhz9nbtVGXYXCTcSuyExyWt5LodoVsnlLQFi1A6DHmdRVfLZN6OWZ6ztxIH6NdmNR4nW9JgTuBe02zxO/fNLEcjI5YIUzQnEtuIKGVpN/w7Nw8s 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 1/14/26 07:07, Hao Li wrote: >> @@ -4836,68 +4558,31 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, >> if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) { >> freelist = alloc_single_from_new_slab(s, slab, orig_size, gfpflags); >> >> - if (unlikely(!freelist)) { >> - /* This could cause an endless loop. Fail instead. */ >> - if (!allow_spin) >> - return NULL; >> - goto new_objects; >> + if (likely(freelist)) { >> + goto success; >> } >> + } else { >> + alloc_from_new_slab(s, slab, &freelist, 1, allow_spin); > > IIUC, when CONFIG_SLUB_DEBUG is enabled, each successful new_slab() call > should have a matching inc_slabs_node(), since __kmem_cache_shutdown() > rely on the accounting done by inc_slabs_node(). Here > alloc_single_from_new_slab() does call inc_slabs_node(), but > alloc_from_new_slab() doesn't. Could this mismatch cause any issues? Great spot, thanks a lot! Yes we should do inc_slabs_node() here. >> >> - if (s->flags & SLAB_STORE_USER) >> - set_track(s, freelist, TRACK_ALLOC, addr, >> - gfpflags & ~(__GFP_DIRECT_RECLAIM)); >> - >> - return freelist; >> - } >> - >> - /* >> - * No other reference to the slab yet so we can >> - * muck around with it freely without cmpxchg >> - */ >> - freelist = slab->freelist; >> - slab->freelist = NULL; >> - slab->inuse = slab->objects; >> - slab->frozen = 1; >> -