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Fri, 24 Oct 2025 08:38:20 +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 uD6MHfw6+2jiXwAAD6G6ig (envelope-from ); Fri, 24 Oct 2025 08:38:20 +0000 Message-ID: <50e96fd8-114b-4de3-939e-9ba606e64b06@suse.cz> Date: Fri, 24 Oct 2025 10:38:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] slab, block: generalize bvec_alloc_gfp Content-Language: en-US To: Christoph Hellwig , Jens Axboe Cc: Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , "Martin K. Petersen" , linux-block@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan References: <20251023080919.9209-1-hch@lst.de> <20251023080919.9209-2-hch@lst.de> 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: <20251023080919.9209-2-hch@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 81CE520004 X-Rspamd-Server: rspam02 X-Stat-Signature: eebrs5uc7akqb7rwipoj61ppipx3drqy X-HE-Tag: 1761295110-765427 X-HE-Meta: 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 Z0MjRdBB ZkxLuuTdRw8hT6CY= 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 10/23/25 10:08, Christoph Hellwig wrote: > bvec_alloc_gfp is useful for any place that tries to kmalloc first and > then fall back to a mempool. Rename it and move it to blk.h to prepare I wonder if such fall backs are necessary because IIRC mempools try to allocate from the underlying provider (i.e. kmalloc caches first), and only give out the reserves when that fails. Is it done for less overhead or something? > for using it to allocate the default integrity buffer. > > Signed-off-by: Christoph Hellwig That says blk.h but you move it to slab.h? Assuming you intended slab.h. However gfp flags are not slab only so it should be rather include/linux/gfp.h - added maintainers of that to Cc. We do have gfp_nested_mask() there which is quite similar but not exactly. Maybe a canonical macro not for nested, but for opportunistic allocations (if a one size fits all solution can be found) would be useful too, as people indeed reinvent those manually in various places with subtle differences. > --- > block/bio.c | 13 ++----------- > include/linux/slab.h | 10 ++++++++++ > 2 files changed, 12 insertions(+), 11 deletions(-) > > diff --git a/block/bio.c b/block/bio.c > index b3a79285c278..4ea5833a7637 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -169,16 +169,6 @@ void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs) > kmem_cache_free(biovec_slab(nr_vecs)->slab, bv); > } > > -/* > - * Make the first allocation restricted and don't dump info on allocation > - * failures, since we'll fall back to the mempool in case of failure. > - */ > -static inline gfp_t bvec_alloc_gfp(gfp_t gfp) > -{ > - return (gfp & ~(__GFP_DIRECT_RECLAIM | __GFP_IO)) | > - __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; > -} > - > struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs, > gfp_t gfp_mask) > { > @@ -201,7 +191,8 @@ struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs, > if (*nr_vecs < BIO_MAX_VECS) { > struct bio_vec *bvl; > > - bvl = kmem_cache_alloc(bvs->slab, bvec_alloc_gfp(gfp_mask)); > + bvl = kmem_cache_alloc(bvs->slab, > + try_alloc_gfp(gfp_mask & ~__GFP_IO)); > if (likely(bvl) || !(gfp_mask & __GFP_DIRECT_RECLAIM)) > return bvl; > *nr_vecs = BIO_MAX_VECS; > diff --git a/include/linux/slab.h b/include/linux/slab.h > index d5a8ab98035c..a6672cead03e 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -1113,6 +1113,16 @@ void kfree_rcu_scheduler_running(void); > */ > size_t kmalloc_size_roundup(size_t size); > > +/* > + * Make the first allocation restricted and don't dump info on allocation > + * failures, for callers that will fall back to a mempool in case of failure. > + */ > +static inline gfp_t try_alloc_gfp(gfp_t gfp) > +{ > + return (gfp & ~__GFP_DIRECT_RECLAIM) | > + __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; Note without __GFP_DIRECT_RECLAIM the __GFP_NORETRY is most likely redundant (but doesn't hurt). > +} > + > void __init kmem_cache_init_late(void); > void __init kvfree_rcu_init(void); >