linux-kernel - Re: [PATCH][Resend v2] Fix infinite loop in search_binary

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Message-Id: <201107051155.18465.richard@nod.at>
Date:	Tue, 5 Jul 2011 11:55:18 +0200
From:	Richard Weinberger <richard@....at>
To:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:	viro@...iv.linux.org.uk, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH][Resend v2] Fix infinite loop in search_binary_handler()

Am Dienstag 05 Juli 2011, 03:24:14 schrieb Tetsuo Handa:
> Richard Weinberger wrote:
> > With MAX_KMOD_CONCURRENT=3 it takes only a few seconds until
> > the modprobe storm ends.
> 
> OK. Many years ago, I got a few reports that the kernel panics after
> printing
> 
>   request_module: runaway loop modprobe binfmt-464c
> 
> line. This was because they installed by error a binary x86_32 kernel rpm
> on x86_64 userland tools. So, this error is not specific to UML.
> 
> > How shall we proceed?
> > Applying my ad-hoc patch
> > or lowering MAX_KMOD_CONCURRENT?
> 
> What about disallowing request_module() for ____call_usermodehelper()
> threads?

This patch helps.
But IMHO adding a new attribute to task_struct is a bit overkill.
Why is your variant better than my strcmp() in fs/exec.c?

Thanks,
//richard
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