linux-kernel - Re: [PATCH 1/2] SLUB: Fix merged slab cache names

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Date:	Tue, 14 Sep 2010 11:02:39 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux.com>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH 1/2] SLUB: Fix merged slab cache names

On Tue, Sep 14, 2010 at 10:06 AM, Pekka Enberg <penberg@...nel.org> wrote:
>
> @@ -3218,6 +3221,18 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
>        down_write(&slub_lock);
>        s = find_mergeable(size, align, flags, name, ctor);
>        if (s) {
> +               if (!(s->flags & SLAB_DYNAMIC_NAME)) {
> +                       const char *new_name;
> +
> +                       new_name = kstrdup(s->name, GFP_KERNEL);
> +                       if (!new_name)
> +                               goto err;
> +
> +                       s->name = new_name;

Once you do this, please actually update the name to list the first
few different names.

Since the SLAB_DYNAMIC_NAME test mean that this will only happen once,
I would suggest something like just doing

   size = strlen(s->name) + strlen(name) + sizeof(", ...");
   new_name = kmalloc(size, GFP_KERNEL);
   if (!new_name)
      return -ENOMEM;
   snprintf(new_name, "%s, %s...", s->name, name);

so that you get the two first names listed. Sure, it will be
wrong/incomplete if there's lots of merging, but it will be visually
very obvious in /proc/slabinfo and in the debug messages.

                  Linus
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