Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 26 Mar 2021 14:48:41 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     io-uring@vger.kernel.org, torvalds@linux-foundation.org,
        ebiederm@xmission.com, metze@samba.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/8] kernel: unmask SIGSTOP for IO threads
Message-ID: <20210326134840.GA1290@redhat.com>
References: <20210326003928.978750-1-axboe@kernel.dk>
 <20210326003928.978750-3-axboe@kernel.dk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210326003928.978750-3-axboe@kernel.dk>
User-Agent: Mutt/1.5.24 (2015-08-30)
Precedence: bulk

Jens, sorry, I got lost :/

On 03/25, Jens Axboe wrote:
>
> With IO threads accepting signals, including SIGSTOP,

where can I find this change? Looks like I wasn't cc'ed...

> unmask the
> SIGSTOP signal from the default blocked mask.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  kernel/fork.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/fork.c b/kernel/fork.c
> index d3171e8e88e5..d5a40552910f 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -2435,7 +2435,7 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
>  	tsk = copy_process(NULL, 0, node, &args);
>  	if (!IS_ERR(tsk)) {
>  		sigfillset(&tsk->blocked);
> -		sigdelsetmask(&tsk->blocked, sigmask(SIGKILL));
> +		sigdelsetmask(&tsk->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));

siginitsetinv(blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)) but this is minor.

To remind, either way this is racy and can't really help.

And if "IO threads accepting signals" then I don't understand why. Sorry,
I must have missed something.

Oleg.