linux-kernel - Re: [PATCH] x86: Fix memory leak of init_vdso

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Message-ID: <CAObL_7HyjsPKnyDEEa0T8iTetpkd9Hq7RTBymieazzGOsXQLdA@mail.gmail.com>
Date:	Thu, 21 Jul 2011 13:26:36 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	mingo@...hat.com, wzt <wzt.wzt@...il.com>,
	linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
	hpa@...or.com, Michal Hocko <mhocko@...e.cz>,
	Zhitong Wang <zhitong.wangzt@...baba-inc.com>
Subject: Re: [PATCH] x86: Fix memory leak of init_vdso_vars()

On Thu, Jul 21, 2011 at 1:08 PM, Andi Kleen <ak@...ux.intel.com> wrote:
> On Thu, Jul 21, 2011 at 10:33:14AM -0400, Andy Lutomirski wrote:
>> From: Zhitong Wang <wzt.wzt@...il.com>
>>
>> If init_vdso_vars ran out of memory (not very likely), then it would
>> leak a few pages as well.
>>
>> Also rename init_vdso_vars to just init_vdso, since initializing
>> vvars is just about the only thing this function doesn't do.
>
> Just add a GFP_PANIC, there's no way to recover from this.
> Your system will not work without a vdso.

Ingo objected to this before, although I'm not convinved.  Calling
init_vdso_vars more than once will cause major problems (like
double-patching of alternatives).  If there's too little memory for it
to work, then presumably there's also too little memory to start init.
 (Also, I bet that no one ever audited whether the ELF loader works
right if the vDSO failed to load.)

Ingo?

--Andy

>
> -Andi
>
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