linux-kernel - Re: [PATCH] mm: slub: do not warn when allocating slab obj extensions fails

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Message-ID: <CAJuCfpGtb9j1y93bksErU4NfjPX6tGrP6qvMrazx3+M7dJWtxQ@mail.gmail.com>
Date: Wed, 21 May 2025 09:02:54 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Usama Arif <usamaarif642@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, hannes@...xchg.org, shakeel.butt@...ux.dev, 
	vlad.wing@...il.com, linux-mm@...ck.org, kent.overstreet@...ux.dev, 
	cl@...two.org, rientjes@...gle.com, vbabka@...e.cz, roman.gushchin@...ux.dev, 
	harry.yoo@...cle.com, linux-kernel@...r.kernel.org, kernel-team@...a.com
Subject: Re: [PATCH] mm: slub: do not warn when allocating slab obj extensions fails

On Wed, May 21, 2025 at 7:25 AM Usama Arif <usamaarif642@...il.com> wrote:
>
> In memory bound systems, a large number of warnings for failing this
> allocation repeatedly may mask any real issues in the system
> during memory pressure being reported in dmesg. Failing this
> allocation is not indicative of a bug, so remove the warning.
>
> Signed-off-by: Usama Arif <usamaarif642@...il.com>
> Reported-by: Vlad Poenaru <vlad.wing@...il.com>
> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/
> ---
> v1 -> v2:
> - remove the warning completely. We will have a way in the
>   future to indicate that the mem alloc profile is inaccurate.
> ---
>  mm/slub.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index dc9e729e1d26..06ab9a558b73 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2102,9 +2102,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
>
>         slab = virt_to_slab(p);
>         if (!slab_obj_exts(slab) &&
> -           WARN(alloc_slab_obj_exts(slab, s, flags, false),
> -                "%s, %s: Failed to create slab extension vector!\n",
> -                __func__, s->name))
> +           alloc_slab_obj_exts(slab, s, flags, false))

I thought we agreed to having pr_warn_once() here. Did I miss something?

>                 return NULL;
>
>         return slab_obj_exts(slab) + obj_to_index(s, slab, p);
> --
> 2.47.1
>