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Tue, 27 Jan 2026 16:35:51 +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 EOcuE2fpeGlAQAAAD6G6ig (envelope-from ); Tue, 27 Jan 2026 16:35:51 +0000 Message-ID: Date: Tue, 27 Jan 2026 17:35:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V1 1/2] mm/slab: factor out slab_args_unmergeable() Content-Language: en-US To: Harry Yoo , Andrew Morton Cc: Christoph Lameter , David Rientjes , Roman Gushchin , Muchun Song , Shakeel Butt , Michal Hocko , Yeoreum Yun , Johannes Weiner , Suren Baghdasaryan , Hai Li , linux-mm@kvack.org References: <20260127103151.21883-1-harry.yoo@oracle.com> <20260127103151.21883-2-harry.yoo@oracle.com> 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: <20260127103151.21883-2-harry.yoo@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam11 X-Stat-Signature: hxdp57o1nr5ac3mknwxb6tydfjjr4s1z X-Rspam-User: X-Rspamd-Queue-Id: 9710C40007 X-HE-Tag: 1769531753-84861 X-HE-Meta: U2FsdGVkX18t6+g+EmcNpA7tj8LusL5nZRch55EK8qnCHSdKx1N0ZBh+9S4YFrpGWMqnpn7tBf97cHX+Zq67Y8rCX5lqnan3ymH6tfLUpKxKOs1o1GY9TGiQEHgbwu34v+7tHPAp0cJ90k8qji0z84/rkbBEbtsjXE1LKnngmRA6rLhrEqGUlSjyI16XcuAHX8Q3jUzFDjAdwZJHvg+jrpO4ipCKaFh4ThgXToGa90E6xwYFcRK+YeoPgvKcLGRgy1diqHFbKnpkrquUqzaMiuzZh4cSBKjRwrM9Gcr6CF61UgZFvMyI37GINRv+Q8tQvXzvoeAur5fl1rxE8VevoNg409A/7tyzs08LOR5aJJTnQ02B5p4qV+5fRl4+NemIj2NTi770DnSs8NXdLJQgc9LEytks7yGA3ianyI8RJUzSIqdTyPcwr5m8D4ha3AUvklFWJ1Ipipi4qLweVxQX1HRiKtoohnmez9SvAQ9G4dBCYUeQpDvh8e6Ymd9USZa5lceYif6gcJxAM1Lq0Nj5CUrbx0KgSMsy2RH18EJcklos6+vDpTukPXOer54JE3ZRYLFm8qH4XFqwIG0PMJUPiez+xr3R96B1o55eSuozQc2GGkhQirRw+Z2zczwiNTOmH5BtpjWANikElV5tQlOFgr8oQJKoj4p9nUJNOHu2ZSFVgns6GNG+LRUAMEc7zF9r9yyJsfeigIfmIFYvItI42LpKgp2S/EEe3LtfREiZHZZoOdG05M+ubOzPwGpBChd9MHObgYjQwBV+jT3BfXTc+NU0G2F+SVHUP6Df+0XfSnSd4ZbELXpZtxUxNMoKOw55wvKYrVqsdA9C9v7nrJoJAZQw0PqlSCGbzBJZt1BIW32n6di5c++4hcF0m6xoaStTbUKOMESEBsVp3WwumFEgwdICzq3t8E27l9lz+S3i01Dy85oxlf3Z/m2u6GNthm8Qq+dhvLcF5eisZ3EhW5q 1XjA3Ncb g33oTNhE38UVPcQSz51Zj8yX54x7cG7Y5eEZ4eUj5z0auVpONXncEJh8upmIuE9HSXpJHio8Gzh1SJ0YwJKBIorRZap4EbBK8FhxzMgc+2zGemfOh2mkt3wSwjEFZoHacVbnoLTVTDG38pihwqn1JTsv8SmO17nmJwzQ+IvH4lkW8Axxx7/CNPO5kTfyXB9w6HX33rEwewwMKs0q022UJsJummWLLToKrbKwUpTJiKv31qS/6P2u7DMkcmYFpLnqQJLmP5ZGlLz73LmrTWDHxmAI9WwJbq104sTKYNAlSPOAHaBABeli4t8AZsf+jKmUPbXuN9BRmGRPBcc06j6LKTjPx+FyEGr6hbKY+MlJmxlknan8= 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 1/27/26 11:31, Harry Yoo wrote: > slab_mergeable() determines whether a slab cache can be merged, but it > should not be used when the cache is not fully created yet. > > Extract the pre-cache-creation mergeability checks into > slab_args_unmergeable(), which evaluates kmem_cache_args, slab flags, > and slab_nomerge to determine if a cache will be mergeable before it is > created. > > Signed-off-by: Harry Yoo > --- > mm/slab_common.c | 28 ++++++++++++++++++---------- > 1 file changed, 18 insertions(+), 10 deletions(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 2e80d323f550..904414c3ebb8 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -174,24 +174,32 @@ int slab_unmergeable(struct kmem_cache *s) > return 0; > } > > -static struct kmem_cache *find_mergeable(unsigned int size, slab_flags_t flags, > - const char *name, struct kmem_cache_args *args) > +static bool slab_args_unmergeable(struct kmem_cache_args *args, > + slab_flags_t flags) > { > - struct kmem_cache *s; > - unsigned int align; > - > if (slab_nomerge) > - return NULL; > + return true; I think this still logically belongs to find_mergeable() and not here, so moved there. Agreed? > if (args->ctor) > - return NULL; > + return true; > > if (IS_ENABLED(CONFIG_HARDENED_USERCOPY) && args->usersize) > - return NULL; > - > - flags = kmem_cache_flags(flags, name); > + return true; > > if (flags & SLAB_NEVER_MERGE) > + return true; > + > + return false; > +} > + > +static struct kmem_cache *find_mergeable(unsigned int size, slab_flags_t flags, > + const char *name, struct kmem_cache_args *args) > +{ > + struct kmem_cache *s; > + unsigned int align; > + > + flags = kmem_cache_flags(flags, name); > + if (slab_args_unmergeable(args, flags)) > return NULL; > > size = ALIGN(size, sizeof(void *));