linux-kernel - Re: [PATCH]: exec: avoid propagating PF_NO

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Message-ID: <20131126180420.GA18172@redhat.com>
Date:	Tue, 26 Nov 2013 19:04:20 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	zhang.yi20@....com.cn
Cc:	htejun@...il.com, lkml <linux-kernel@...r.kernel.org>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH]: exec: avoid propagating PF_NO_SETAFFINITY into
	userspace child

On 11/26, zhang.yi20@....com.cn wrote:
>
> Userspace process doesn't want the PF_NO_SETAFFINITY, but its parent may be
> a kernel worker thread which has PF_NO_SETAFFINITY set.

... and this worker thread can do kernel_thread() to create the child.

> Clearing this flag in usersapce child to enable its migrating capability.
>
>
> Signed-off-by: Zhang Yi <zhang.yi20@....com.cn>
>
> --- linux-3.12.old/fs/exec.c	2013-11-26 08:53:12.175811856 +0000
> +++ linux-3.12/fs/exec.c	2013-11-26 09:26:53.575999604 +0000
> @@ -1091,7 +1091,8 @@ int flush_old_exec(struct linux_binprm *
>
>  	set_fs(USER_DS);
>  	current->flags &=
> -		~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE);
> +		~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE
> +		| PF_NO_SETAFFINITY);

Thanks,

Acked-by: Oleg Nesterov <oleg@...hat.com>




Can't resist... perhaps

	current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
			    PF_NOFREEZE | PF_NO_SETAFFINITY);

looks a bit better, but this is minor and I won't insist.

Oleg.

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