[PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[Usama Arif]

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. Change this to
warning only once.

Signed-off-by: Usama Arif <usamaarif642@gmail.com>
Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/
---
v2 -> v3:
- Put warning back, but only warn once with pr_warn_once.
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 | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index dc9e729e1d26..36d7c43a6f2a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2102,10 +2102,12 @@ 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)) {
+		pr_warn_once("%s, %s: Failed to create slab extension vector!\n",
+			__func__, s->name);
 		return NULL;
+	}
+
 
 	return slab_obj_exts(slab) + obj_to_index(s, slab, p);
 }
-- 
2.47.1

Re: [PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[Shakeel Butt]

On Fri, May 23, 2025 at 05:52:40PM +0100, Usama Arif 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. Change this to
> warning only once.
> 
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/

Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>

Re: [PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[SeongJae Park]

On Fri, 23 May 2025 17:52:40 +0100 Usama Arif <usamaarif642@gmail.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. Change this to
> warning only once.
> 
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[Vlastimil Babka]

On 5/23/25 18:52, Usama Arif 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. Change this to
> warning only once.
> 
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/
> ---
> v2 -> v3:
> - Put warning back, but only warn once with pr_warn_once.
> 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 | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index dc9e729e1d26..36d7c43a6f2a 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2102,10 +2102,12 @@ 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)) {
> +		pr_warn_once("%s, %s: Failed to create slab extension vector!\n",
> +			__func__, s->name);
>  		return NULL;
> +	}
> +

I've removed the extra line locally.

Added to slab/for-next, thanks.

>  
>  	return slab_obj_exts(slab) + obj_to_index(s, slab, p);
>  }

Re: [PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[Harry Yoo]

On Fri, May 23, 2025 at 05:52:40PM +0100, Usama Arif 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. Change this to
> warning only once.
> 
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
> Closes: https://urldefense.com/v3/__https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/__;!!ACWV5N9M2RV99hQ!Nv5xX_X4cBQR_HUDO6qfamxI0GEW1eFRCpPj29lANRashIUJDrEWAjU7vlys76FH0voShW07CjpDkzSST46Irg$ 
> ---

Acked-by: Harry Yoo <harry.yoo@oracle.com>

> v2 -> v3:
> - Put warning back, but only warn once with pr_warn_once.
> 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 | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index dc9e729e1d26..36d7c43a6f2a 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2102,10 +2102,12 @@ 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)) {
> +		pr_warn_once("%s, %s: Failed to create slab extension vector!\n",
> +			__func__, s->name);
>  		return NULL;
> +	}
> +
>  
>  	return slab_obj_exts(slab) + obj_to_index(s, slab, p);
>  }
> -- 
> 2.47.1
> 

-- 
Cheers,
Harry / Hyeonggon

Re: [PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[Suren Baghdasaryan]

On Mon, May 26, 2025 at 3:05 AM Harry Yoo <harry.yoo@oracle.com> wrote:
>
> On Fri, May 23, 2025 at 05:52:40PM +0100, Usama Arif 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. Change this to
> > warning only once.
> >
> > Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> > Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
> > Closes: https://urldefense.com/v3/__https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/__;!!ACWV5N9M2RV99hQ!Nv5xX_X4cBQR_HUDO6qfamxI0GEW1eFRCpPj29lANRashIUJDrEWAjU7vlys76FH0voShW07CjpDkzSST46Irg$
> > ---
>
> Acked-by: Harry Yoo <harry.yoo@oracle.com>

Acked-by: Suren Baghdasaryan <surenb@google.com>

>
> > v2 -> v3:
> > - Put warning back, but only warn once with pr_warn_once.
> > 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 | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/slub.c b/mm/slub.c
> > index dc9e729e1d26..36d7c43a6f2a 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -2102,10 +2102,12 @@ 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)) {
> > +             pr_warn_once("%s, %s: Failed to create slab extension vector!\n",
> > +                     __func__, s->name);
> >               return NULL;
> > +     }
> > +
> >
> >       return slab_obj_exts(slab) + obj_to_index(s, slab, p);
> >  }
> > --
> > 2.47.1
> >
>
> --
> Cheers,
> Harry / Hyeonggon

Re: [PATCH v3] mm: slub: only warn once when allocating slab obj extensions fails

[Roman Gushchin]

Usama Arif <usamaarif642@gmail.com> writes:

> 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. Change this to
> warning only once.
>
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> Reported-by: Vlad Poenaru <vlad.wing@gmail.com>
> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/

Acked-by: Roman Gushchin <roman.gushchin@linux.dev>

Thanks!