From: Kautuk Consul <consul.kautuk@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>,
Al Viro <viro@zeniv.linux.org.uk>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] mmap.c: find_vma: remove if(mm) check
Date: Wed, 28 Mar 2012 09:13:00 +0530 [thread overview]
Message-ID: <CAFPAmTR67R6aF9U7-idXGDsbfvhTxEn=D3pu_Jjhq37rhcez8Q@mail.gmail.com> (raw)
In-Reply-To: <20120327151238.302a5920.akpm@linux-foundation.org>
On Wed, Mar 28, 2012 at 3:42 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Mon, 26 Mar 2012 19:49:27 -0400
> Kautuk Consul <consul.kautuk@gmail.com> wrote:
>
>> find_vma is called from kernel code where it is absolutely
>> sure that the mm_struct arg being passed to it is non-NULL.
>>
>> Remove the if(mm) check.
>
> It's odd that the if(mm) test exists - I wonder why it was originally
> added. My repo only goes back ten years, and it's there in 2.4.18.
>
> Any code which calls find_vma() without an mm is surely pretty busted?
>
>
> Still, I think I'd prefer to do
>
> if (WARN_ON_ONCE(!mm))
> return NULL;
>
yes, I agree. that is safe for now as there are a huge number of calls
to this API.
> then let that bake for a kernel release, just to find out if we have a
> weird caller out there, such as a function which is called by both user
> threads and by kernel threads.
ok. I'll spin another one and send it to you with your suggestions in a day or
two when I go back home after my day job.
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prev parent reply other threads:[~2012-03-28 3:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-26 23:49 Kautuk Consul
2012-03-27 22:12 ` Andrew Morton
2012-03-28 3:43 ` Kautuk Consul [this message]
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