From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>, Linux-MM <linux-mm@kvack.org>
Subject: Re: [patch V4 01/32] mm/slab: Fix broken stack trace storage
Date: Mon, 15 Apr 2019 08:23:39 -0500 [thread overview]
Message-ID: <20190415132339.wiqyzygqklliyml7@treble> (raw)
In-Reply-To: <alpine.DEB.2.21.1904151101100.1729@nanos.tec.linutronix.de>
On Mon, Apr 15, 2019 at 11:02:58AM +0200, Thomas Gleixner wrote:
> kstack_end() is broken on interrupt stacks as they are not guaranteed to be
> sized THREAD_SIZE and THREAD_SIZE aligned.
>
> Use the stack tracer instead. Remove the pointless pointer increment at the
> end of the function while at it.
>
> Fixes: 98eb235b7feb ("[PATCH] page unmapping debug") - History tree
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: linux-mm@kvack.org
> ---
> V4: Made the code simpler to understand (Andy) and make it actually compile
> ---
> mm/slab.c | 30 ++++++++++++++----------------
> 1 file changed, 14 insertions(+), 16 deletions(-)
>
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -1470,33 +1470,31 @@ static bool is_debug_pagealloc_cache(str
> static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
> unsigned long caller)
> {
> - int size = cachep->object_size;
> + int size = cachep->object_size / sizeof(unsigned long);
>
> addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];
>
> - if (size < 5 * sizeof(unsigned long))
> + if (size < 5)
> return;
>
> *addr++ = 0x12345678;
> *addr++ = caller;
> *addr++ = smp_processor_id();
> - size -= 3 * sizeof(unsigned long);
> + size -= 3;
> +#ifdef CONFIG_STACKTRACE
> {
> - unsigned long *sptr = &caller;
> - unsigned long svalue;
> -
> - while (!kstack_end(sptr)) {
> - svalue = *sptr++;
> - if (kernel_text_address(svalue)) {
> - *addr++ = svalue;
> - size -= sizeof(unsigned long);
> - if (size <= sizeof(unsigned long))
> - break;
> - }
> - }
> + struct stack_trace trace = {
> + /* Leave one for the end marker below */
> + .max_entries = size - 1,
> + .entries = addr,
> + .skip = 3,
> + };
>
> + save_stack_trace(&trace);
> + addr += trace.nr_entries;
> }
> - *addr++ = 0x87654321;
> +#endif
> + *addr = 0x87654321;
Looks like stack_trace.nr_entries isn't initialized? (though this code
gets eventually replaced by a later patch)
Who actually reads this stack trace? I couldn't find a consumer.
--
Josh
next prev parent reply other threads:[~2019-04-15 13:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190414155936.679808307@linutronix.de>
2019-04-14 15:59 ` [patch V3 01/32] mm/slab: Fix broken stack trace storage Thomas Gleixner
2019-04-14 16:16 ` Andy Lutomirski
2019-04-14 16:34 ` Thomas Gleixner
2019-04-15 9:02 ` [patch V4 " Thomas Gleixner
2019-04-15 13:23 ` Josh Poimboeuf [this message]
2019-04-15 16:07 ` Thomas Gleixner
2019-04-15 16:16 ` Josh Poimboeuf
2019-04-15 17:05 ` Andy Lutomirski
2019-04-15 21:22 ` Thomas Gleixner
2019-04-16 11:37 ` Vlastimil Babka
2019-04-16 14:10 ` [patch V5 01/32] mm/slab: Remove " Thomas Gleixner
2019-04-16 15:16 ` Vlastimil Babka
2019-04-15 21:20 ` [patch V4 01/32] mm/slab: Fix " Thomas Gleixner
2019-04-15 16:21 ` Peter Zijlstra
2019-04-15 16:58 ` [patch V3 " Andy Lutomirski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190415132339.wiqyzygqklliyml7@treble \
--to=jpoimboe@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=penberg@kernel.org \
--cc=sean.j.christopherson@intel.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).