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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sun, 10 Dec 2017 12:45:10 -0800
Message-ID: <CA+55aFzE0Z98KRT4rk3f3R0BcMqGMrHWHsaB9Aq02etwWm_hjg@mail.gmail.com>
Subject: Re: [PATCH] mm/slab: Do not hash pointers when debugging slab
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Tobin C . Harding" <me@tobin.cc>, linux-mm <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Thu, Dec 7, 2017 at 2:17 AM, Geert Uytterhoeven
<geert+renesas@glider.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