Messages in this thread |  | | | Date | Mon, 21 Apr 2008 21:20:58 -0700 | | From | Arjan van de Ven <> | | Subject | Re: [PATCH] use canary at end of stack to indicate overruns at oops time | |
On Mon, 21 Apr 2008 22:44:39 -0500
Eric Sandeen <sandeen@redhat.com> wrote:
> Use a canary at the end of the stack to clearly indicate
> at oops time whether the stack has ever overflowed.
>
> This is a very simple implementation with a couple of
> drawbacks:
>
> 1) a thread may legitimately use exactly up to the last
> word on the stack
>
> -- but the chances of doing this and then oopsing later seem slim
>
> 2) it's possible that the stack usage isn't dense enough
> that the canary location could get skipped over
>
> -- but the worst that happens is that we don't flag the overrun
>
> With the code in place, an intentionally-bloated stack oops does:
>
> BUG: unable to handle kernel paging request at ffff8103f84cc680
> IP: [<ffffffff810253df>] update_curr+0x9a/0xa8
> PGD 8063 PUD 0
> Thread overran stack or stack corrupted
> Oops: 0000 [1] SMP
> CPU 0
I like this but I wonder if it's useful to do this for the irq stacks too;
either way
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
(I'll also add detection of your printk to the kerneloops.org website)
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