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Tue, 27 Jan 2026 16:49:12 +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 bZKxDYjseGnsTAAAD6G6ig (envelope-from ); Tue, 27 Jan 2026 16:49:12 +0000 Message-ID: <62706310-5144-4edf-8377-540ee947181f@suse.cz> Date: Tue, 27 Jan 2026 17:49:11 +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 Cc: Andrew Morton , 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam11 X-Stat-Signature: 6trkgou3i7dk7cfknsdoz6whmqbtah1h X-Rspam-User: X-Rspamd-Queue-Id: 6D66240011 X-HE-Tag: 1769532554-766646 X-HE-Meta: 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 rXq4ZIUa NPjgEB3RECbK7IKw= 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 17:42, Harry Yoo wrote: > On Tue, Jan 27, 2026 at 05:35:50PM +0100, Vlastimil Babka wrote: >> 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? > > But then patch 2/2 should be modified to check slab_nomerge then? Yeah I would do that as well, > And even slab_unmergeable() does slab_nomerge check, so perhaps it's > more consistent to do it in slab_args_unmergeable(). But this is true so I'll leave both as you did, thanks!