Re: frequent slab corruption (since a long time)

From: Dave Jones
Date: Wed Aug 02 2006 - 18:21:16 EST


On Tue, Aug 01, 2006 at 10:31:10PM -0700, David Miller wrote:
> From: David Miller <davem@xxxxxxxxxxxxx>
> Date: Tue, 01 Aug 2006 22:05:38 -0700 (PDT)
>
> > The corruption is always a 32-bit 0xffffffff followed by
> > a 32-bit 0x00000000, 12 bytes into the object.
>
> This analysis is wrong, it's "0xb0 + 12" bytes into the object
> which is 188 bytes. For x86, this lands us at the "count"
> member of the tty_struct, and it shows that the tty count
> has decremented to -1 (0xffffffff) which is a serious bug.

<stabbing in the dark here>

None of the code manipulating tty->count seems to be under
the tty_mutex. Should it be ?
Or is this protected through some other means?

Jason, ISTR you've done some digging around this area wrt races,
any insight ?

Dave

--
http://www.codemonkey.org.uk
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