Messages in this thread | | | Date | Sat, 31 Jan 2015 11:18:37 +0700 | From | Arseny Solokha <> | Subject | Re: [PATCH] powerpc/mm: bail out early when flushing TLB page |
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> 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.
Just a code inspection. It didn't seemed right at the first glance.
Arsény
> > -Scott
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