* Re: slub: don't panic for memcg kmem cache creation failure
@ 2019-06-29 14:05 Alexey Dobriyan
2019-06-29 20:31 ` Shakeel Butt
0 siblings, 1 reply; 2+ messages in thread
From: Alexey Dobriyan @ 2019-06-29 14:05 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel, shakeelb, dave.hansen, rientjes, mhocko
> - if (flags & SLAB_PANIC)
> - panic("Cannot create slab %s size=%u realsize=%u order=%u offset=%u flags=%lx\n",
> - s->name, s->size, s->size,
> - oo_order(s->oo), s->offset, (unsigned long)flags);
This is wrong. Without SLAB_PANIC people will start to implement error
checking out of habit and add all slightly different error messages.
This simply increases text and rodata size.
If memcg kmem caches creation failure is OK, then SLAB_PANIC should not
be passed.
The fact that SLAB doesn't implement SLAB_PANIC is SLAB bug.
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: slub: don't panic for memcg kmem cache creation failure
2019-06-29 14:05 slub: don't panic for memcg kmem cache creation failure Alexey Dobriyan
@ 2019-06-29 20:31 ` Shakeel Butt
0 siblings, 0 replies; 2+ messages in thread
From: Shakeel Butt @ 2019-06-29 20:31 UTC (permalink / raw)
To: Alexey Dobriyan
Cc: Andrew Morton, LKML, Dave Hansen, David Rientjes, Michal Hocko
On Sat, Jun 29, 2019 at 7:05 AM Alexey Dobriyan <adobriyan@gmail.com> wrote:
>
> > - if (flags & SLAB_PANIC)
> > - panic("Cannot create slab %s size=%u realsize=%u order=%u offset=%u flags=%lx\n",
> > - s->name, s->size, s->size,
> > - oo_order(s->oo), s->offset, (unsigned long)flags);
>
> This is wrong. Without SLAB_PANIC people will start to implement error
> checking out of habit and add all slightly different error messages.
> This simply increases text and rodata size.
>
> If memcg kmem caches creation failure is OK, then SLAB_PANIC should not
> be passed.
>
> The fact that SLAB doesn't implement SLAB_PANIC is SLAB bug.
I do not agree with you. IMHO the kmem_cache_create_usercopy() is the
right place to handle SLAB_PANIC which is handling it. If you want
extra info here, you can add pr_warn for SLAB_PANIC here and the
caller will still and rightfully do the panic().
thanks,
Shakeel
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-06-29 14:05 slub: don't panic for memcg kmem cache creation failure Alexey Dobriyan
2019-06-29 20:31 ` Shakeel Butt
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