linux-kernel - Re: slub: don't panic for memcg kmem cache creation failure

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Message-ID: <20190629140533.GA10164@avx2>
Date:   Sat, 29 Jun 2019 17:05:33 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, shakeelb@...gle.com,
        dave.hansen@...el.com, rientjes@...gle.com, mhocko@...e.com
Subject: Re: slub: don't panic for memcg kmem cache creation failure

> -       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.