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boundary="------------wKfn6SOhJ4zncBuTwBK74Tnp"; protected-headers="v1" From: Harry Yoo To: "Vlastimil Babka (SUSE)" , Shakeel Butt Cc: Andrew Morton , Roman Gushchin , Hao Li , Christoph Lameter , David Rientjes , Suren Baghdasaryan , Usama Arif , Meta kernel team , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danielle Costantino Message-ID: <0a5bd822-5076-4dc5-9c99-8b4a36d119a2@kernel.org> Subject: Re: [PATCH] mm/slub: serve slabobj_ext array from a strictly larger kmalloc cache References: <20260625230029.703750-1-shakeel.butt@linux.dev> <62453403-954c-4cf1-8924-6d38184b0810@kernel.org> <09267187-6c85-438f-8791-4cce8d07892a@kernel.org> <0925f783-1506-4a20-ab9a-3130c2f07ed3@kernel.org> In-Reply-To: <0925f783-1506-4a20-ab9a-3130c2f07ed3@kernel.org> --------------wKfn6SOhJ4zncBuTwBK74Tnp Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 6/28/26 5:10 PM, Harry Yoo wrote: >=20 >=20 > On 6/27/26 2:11 AM, Vlastimil Babka (SUSE) wrote: >> Minimally I'd now want to only do that size bumping when allocation >> profiling is enabled. Ideally that means both configured in and not bo= oted >> with "never". >> >> We probably should have done that already in 280ea9c3154b2. >=20 > I think we did already. >=20 > obj_exts allocation triggered by memcg has __GFP_ACCOUNT, kmalloc type > is KMALLOC_CGROUP, and so is_kmalloc_normal() should return false? >=20 > Perhaps a comment above !is_kmalloc_normal() check would be nice. >=20 >> Because AFAIU >> memcg-only obj_exts array don't have this issue >> (or maybe they do have the > [1] issue? Harry?). >=20 > memcg-only obj_exts array doesn't have this issue and [1]. >> Because obj_exts are not accounted and so we can't allocate obj_exts > from KMALLOC_CGROUP. Oh god, I am confused again! Commit 8dafa9f5900c says it might have this issue. However is_kmalloc_normal(s) =3D=3D true detects that it might hav= e the problem when either 1) memory allocation profiling is enabled, or 2) SLUB_TINY w/ __GFP_RECLAIMABLE|__GFP_ACCOUNT allocates accounted slab objects from KMALLOC_NORMAL. --=20 Cheers, Harry / Hyeonggon --------------wKfn6SOhJ4zncBuTwBK74Tnp-- --------------3GfxXd63I9ObqmVAjGuD5Xr0 Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCakDc9QAKCRCGXBN6rc5S 1jIeAP4qtq+NisEYFpv03iiMzdPr6nve/wHx8YPlWmcM0mTcaQEAnILwYYfktP41 1GWR1qw3TzgjwtzfndemUjSIV6ZG1ws= =BhXu -----END PGP SIGNATURE----- --------------3GfxXd63I9ObqmVAjGuD5Xr0--