linux-kernel - Re: [PATCH] mm/slab: Do not hash pointers when debugging slab

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Date:   Sun, 10 Dec 2017 12:45:10 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Tobin C . Harding" <me@...in.cc>, linux-mm <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/slab: Do not hash pointers when debugging slab

On Thu, Dec 7, 2017 at 2:17 AM, Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
>
>         if (cachep->flags & SLAB_STORE_USER) {
> -               pr_err("Last user: [<%p>](%pSR)\n",
> +               pr_err("Last user: [<%px>](%pSR)\n",
>                        *dbg_userword(cachep, objp),
>                        *dbg_userword(cachep, objp));

Is there actually any point to the %px at all?

Why not remove it? the _real_ information is printed out by %pSR, and
that's both sufficient and useful in ways %px isn't.

> -                               pr_err("Slab corruption (%s): %s start=%p, len=%d\n",
> +                               pr_err("Slab corruption (%s): %s start=%px, len=%d\n",
>                                        print_tainted(), cachep->name,
>                                        realobj, size);

and here, is the pointer actually interesting, or should we just give
the offset to the allocation?

But if the pointer is interesting, then ack.

              Linus