[PATCH] powerpc/mm: bail out early when flushing TLB page
Scott Wood
scottwood at freescale.com
Sat Jan 31 08:53:01 AEDT 2015
On Fri, 2015-01-30 at 19:08 +0700, Arseny Solokha wrote:
> MMU_NO_CONTEXT is conditionally defined as 0 or (unsigned int)-1.
For nohash it is specifically -1.
> However, in __flush_tlb_page() a corresponding variable is only tested
> for open coded 0, which can cause NULL pointer dereference if `mm'
> argument was legitimately passed as such.
>
> Bail out early in case the first argument is NULL, thus eliminate confusion
> between different values of MMU_NO_CONTEXT and avoid disabling and then
> re-enabling preemption unnecessarily.
How did you notice this? Did you see an oops, or was it code
inspection? I'm wondering what codepath gets here with mm == NULL.
-Scott
More information about the Linuxppc-dev
mailing list