From: Scott Wood <scottwood@freescale.com>
To: Arseny Solokha <asolokha@kb.kras.ru>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
<linuxppc-dev@lists.ozlabs.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] powerpc/mm: bail out early when flushing TLB page
Date: Fri, 30 Jan 2015 15:53:01 -0600 [thread overview]
Message-ID: <1422654781.10544.173.camel@freescale.com> (raw)
In-Reply-To: <1422619707-30864-1-git-send-email-asolokha@kb.kras.ru>
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
next prev parent reply other threads:[~2015-01-30 21:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-30 12:08 Arseny Solokha
2015-01-30 21:53 ` Scott Wood [this message]
2015-01-31 4:18 ` Arseny Solokha
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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