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Howlett" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260710-kmalloc-no-objext-v2-0-2709afb6a030@kernel.org> <32a056e2-e641-4aaa-887e-586d997feefc@kernel.org> Content-Language: en-US From: Harry Yoo In-Reply-To: <32a056e2-e641-4aaa-887e-586d997feefc@kernel.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------bh0iCJLSq0YYjqkEhFMD4qVf" X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 32BD112000D X-Stat-Signature: 8weye46dotb3yb56cdayx7gpr1esffs1 X-HE-Tag: 1783691098-57290 X-HE-Meta: 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 StQERx1n JEFUxyug0QV4wLW2icW/UIfIJFhZgFIIV48t+Jup5+84XwU4QBNQmjMm9ZPnUkWggXsbFtgeN2WCKpwOarldgLJssQZGZt3RH/mIO8fz7EIMEHl9gNeBsgLiKiSQS0HommC3sbyT0YsAx3Gi3QhIGF1dJleGwkbV1PzrcELSPtEqi30HvbLEVC7qz9G5P8Xmi4ixzkOMWJJY3MO6ax+KqNFRVuDhhMIRN6xTghMWBk6pMowldOYadZZAHjqMNS8tIIuDRsLrE7cZwL+gS+LPOAWiNNK1daTWBQVuFJfwzGB2LOTyVdwSFFqfKz6wEUatKBfk7sXerrAY32ELXzm9xSPirrT6JjNCfMjHIp+xF6msJ9B5LUbypkl96U3N6VLJhpw9m0m/BESGuZOeDc00TPKwaINRfyqj7ZNETGDYILiTPdM8Z6eo/XbtrtnRwfGa21yLb26TTPTb1KeVsIdsUh6joGYlHHBuQmGhh Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------bh0iCJLSq0YYjqkEhFMD4qVf Content-Type: multipart/mixed; boundary="------------LHSebdT4vB2ZGMN1riwkJEZQ"; protected-headers="v1" From: Harry Yoo To: "Vlastimil Babka (SUSE)" , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Suren Baghdasaryan , Hao Ge , Kees Cook , Pedro Falcato , Shakeel Butt , Danielle Constantino , "Liam R. Howlett" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Message-ID: <4a5c8eb6-90f4-412a-93bf-21360fce3c7a@kernel.org> Subject: Re: [PATCH slab/for-next-fixes v2 0/3] mm/slab: fix unbounded recursion in free path with memalloc profiling References: <20260710-kmalloc-no-objext-v2-0-2709afb6a030@kernel.org> <32a056e2-e641-4aaa-887e-586d997feefc@kernel.org> In-Reply-To: <32a056e2-e641-4aaa-887e-586d997feefc@kernel.org> --------------LHSebdT4vB2ZGMN1riwkJEZQ Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 7/10/26 10:07 PM, Vlastimil Babka (SUSE) wrote: > On 7/10/26 08:03, Harry Yoo (Oracle) wrote: >> This is a follow-up fix after the recent discussion [1]. >> See patch 2 for the detailed description on the bug. >> >> Based on slab/for-next-fixes (72bb229f916) and will be soon available >> at git.kernel.org [2]. >> >> Instead preventing cycles by bumping up the allocation size of obj_ext= s >> arrays, it introduces a new kmalloc type called KMALLOC_NO_OBJ_EXT and= >> disallow formation of cycles between kmalloc types when allocating >> obj_exts arrays. obj_exts arrays of normal kmalloc caches are served >> from KMALLOC_NO_OBJ_EXT caches (that don't have obj_exts), and all oth= er >> obj_exts arrays are served from normal kmalloc caches. >=20 > Since we agreed to investigate later whether it makes sense to start > allocating all obj_ext allocations from the new type, I wonder if for n= ow we > should not create them at all if they won't be used - if anything to av= oid > polluting slabinfo. That's fair point! > AFAIU that means only create them with mem alloc > profiling is config-enabled and mem_profiling_support =3D=3D true? assuming mem_profiling_support =3D=3D true means not "never"... > (Or probably also with SLUB_TINY && MEMCG, as nonsensical as it is...) I'll instead check "is any kmalloc type w/ higher priority than KMALLOC_CGROUP aliased with KMALLOC_NORMAL?", which would be IS_ENABLED(CONFIG_MEMCG) && (KMALLOC_DMA =3D=3D KMALLOC_NORMAL || KMALLOC_RECLAIM =3D=3D KMALLOC_NORM= AL), --=20 Cheers, Harry / Hyeonggon --------------LHSebdT4vB2ZGMN1riwkJEZQ-- --------------bh0iCJLSq0YYjqkEhFMD4qVf Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCalD3QwAKCRCGXBN6rc5S 1rBbAP9swMPew8X20cwWuwn1XEQImWWSR2qmMZhLty5iWRZ7oQEA0a/HLzON3ljk jBI8WgyBFx/efIAV1Ekatq5opFy5Pw4= =EFDt -----END PGP SIGNATURE----- --------------bh0iCJLSq0YYjqkEhFMD4qVf--