From: Arseny Solokha <asolokha@kb.kras.ru>
To: Scott Wood <scottwood@freescale.com>
Cc: Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/mm: bail out early when flushing TLB page
Date: Sat, 31 Jan 2015 11:18:37 +0700 [thread overview]
Message-ID: <54CC579D.1070709@kb.kras.ru> (raw)
In-Reply-To: <1422654781.10544.173.camel@freescale.com>
> 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
next prev parent reply other threads:[~2015-01-31 4:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-30 12:08 [PATCH] powerpc/mm: bail out early when flushing TLB page Arseny Solokha
2015-01-30 21:53 ` Scott Wood
2015-01-31 4:18 ` Arseny Solokha [this message]
2015-01-31 20:27 ` Benjamin Herrenschmidt
2015-02-02 5:07 ` Arseny Solokha
2015-02-02 5:28 ` [PATCH] powerpc/mm: warn on flushing tlb page in kernel context Arseny Solokha
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