linux-kernel - Re: [PATCH] coredump: fix unfreezable coredumping task

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Date:   Mon, 7 Nov 2016 19:27:09 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>, "Oleg Nesterov" <oleg@...hat.com>
CC:     <linux-pm@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] coredump: fix unfreezable coredumping task

On 09/30/2016 11:50 AM, Andrey Ryabinin wrote:
> It could be not possible to freeze coredumping task when it waits
> for 'core_state->startup' completion, because threads are frozen
> in get_signal() before they got a chance to complete 'core_state->startup'.
> 
> Use freezer_do_not_count() to tell freezer to ignore coredumping
> task while it waits for core_state->startup completion.
> 
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: stable@...r.kernel.org
> ---

Ping. Can someone apply this please?

>  fs/coredump.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/coredump.c b/fs/coredump.c
> index 281b768..eb9c92c 100644
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -1,6 +1,7 @@
>  #include <linux/slab.h>
>  #include <linux/file.h>
>  #include <linux/fdtable.h>
> +#include <linux/freezer.h>
>  #include <linux/mm.h>
>  #include <linux/stat.h>
>  #include <linux/fcntl.h>
> @@ -423,7 +424,9 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
>  	if (core_waiters > 0) {
>  		struct core_thread *ptr;
>  
> +		freezer_do_not_count();
>  		wait_for_completion(&core_state->startup);
> +		freezer_count();
>  		/*
>  		 * Wait for all the threads to become inactive, so that
>  		 * all the thread context (extended register state, like
>