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b=hcFkC3n8AHC2UQ/5CKvA8Ur1qGVOq+ZJoimSPsg/lymsNXEw6hDCkD+1aAaKZUzbF EboLoiFXWX6RCKMMS95x5EetuT50ZUevkKpHh1q2EwciC75UP0Bv3S9UG3Zuv2aS7h AomCbO1VGjRn073SkoxHWyKd4LdBvRNa2Qt5PIUKn/UHIGlVUOVWfiR4uVnR5lRkzG 07Jc5gEi5ftmPZVEIS15RXvKVPNoT6My4N+4hJMdEF1crY5YsXQEoIbbIeBODtoOLR tjcrd/wz2PAqaQ3OAmwjn3896pSO2n8c0+gOwHz/G9kN2Ff7rQ0wARl9f9ai/IRfO6 clsd80r3SIm8g== Message-ID: <143ed5f0-67be-451d-a592-e184dd51763a@kernel.org> Date: Wed, 1 Jul 2026 17:43:23 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/slub: serve slabobj_ext array from a strictly larger kmalloc cache From: Harry Yoo To: Suren Baghdasaryan Cc: Shakeel Butt , "Vlastimil Babka (SUSE)" , Andrew Morton , Roman Gushchin , Hao Li , Christoph Lameter , David Rientjes , Usama Arif , Meta kernel team , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danielle Costantino , Kees Cook References: <62969830-4b1f-483d-8fa9-9ce487568570@kernel.org> <39a79576-dcae-4b66-9478-c81dfe676699@kernel.org> <5ebd3c4a-5c06-43b4-ab0a-7a8f0396c84c@kernel.org> <9a139365-28e6-4f1e-b35b-7f6091e9aa14@kernel.org> <92bf5e21-690e-4a77-929e-5217e0d7cb0c@kernel.org> <68e7f6cd-cf11-46b2-84a2-d512bb22dae4@kernel.org> Content-Language: en-US In-Reply-To: <68e7f6cd-cf11-46b2-84a2-d512bb22dae4@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8FDBB1C0003 X-Rspam-User: X-Stat-Signature: u7xgjjgceenktt4om8fmn987mq3db31j X-HE-Tag: 1782895409-119548 X-HE-Meta: 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 oUOIxYeO kaIuOGIkUESb+h/MRnplMxfvUHLB5Ud5IJlAT+Jtd6PBgVjjU2Xu+rwC4Pl8S1PPqIp+ZjsLaTRvtfLCnjd4MCbV0cgGJbgrkaslzKbJpq7rkSXOXRZpYeDW/AWVQDqoI175+XfgAeddzfvkVJYFF5eDrFVyNyh/vCh1ZHbn68UiclPDk+dLyF+YWxTemmo3CcvCNaCzkaljTGgZwZTIBQg4+0N7+gef7lXkXeyUeig/pyMyVn9L8gKj3/3w0fmK7Th+2OTFMwd2yWy6QqOL2vZGa2XcuW80+xgPA6UDc5GIryMtbNP1M2PewXA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/1/26 4:42 PM, Harry Yoo wrote: >=20 >=20 > On 7/1/26 1:53 PM, Harry Yoo wrote: >> >> >> On 7/1/26 1:30 PM, Harry Yoo wrote: >>> We can do that in pre-7.2 kernels, by teaching kmalloc_type() and >>> kmalloc_slab() select the new KMALLOC_TYPE based on __GFP_NO_OBJ_EXT?= >>> >>> e.g.) Select the new KMALLOC_TYPE when KMALLOC_NOT_NORMAL_BITS is not= >>> set AND __GFP_NO_OBJ_EXT is set. >> >> Uh, this is bit subtle though. >> >> In some cases KMALLOC_DMA =3D=3D KMALLOC_NORMAL, >> KMALLOC_CGROUP =3D=3D KMALLOC_NORMAL, >> or KMALLOC_RECLAIM =3D=3D KMALLOC_NORMAL. >> >> Just checking KMALLOC_NOT_NORMAL_BITS is misleading. >=20 > Here's a prototype for slab/for-next. Backporting it requires handling > __GFP_NO_OBJ_EXT instead of SLAB_ALLOC_NO_RECURSE, but shouldn't be > too difficult. Now writing changelog and going through testing... Now thinking about the performance implication of sheaf allocations for kmalloc caches being served from KMALLOC_NO_RECURSE caches won't have sheaves at all --=20 Cheers, Harry / Hyeonggon