[Devel] [PATCH 1/3] Revert "do_SAK: Don't recursively take the tasklist_lock"

[Pavel Tikhomirov]

Now I see that SIGKILL will kill all threads.
Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

On 01/18/2018 12:48 PM, Kirill Tkhai wrote:
> This reverts commit 20ac94378de5.
> 
> send_sig() does not take tasklist_lock for a long time,
> so this commit and the problem it solves are not relevant
> anymore.
> 
> Also, the problem of force_sig() is it clears SIGNAL_UNKILLABLE
> flag, thus even global init may be killed by __do_SAK(),
> which is definitely not the expected behavior.
> 
> Came from discussion in "tty: Iterate only thread group leaders in __do_SAK()"
> https://lkml.org/lkml/2018/1/11/492
> 
> https://jira.sw.ru/browse/PSBM-80340
> 
> Suggested-by: Oleg Nesterov <oleg at redhat.com>
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>   drivers/tty/tty_io.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 719e6edb136c..b46b357a3b76 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -3043,7 +3043,7 @@ void __do_SAK(struct tty_struct *tty)
>   			printk(KERN_NOTICE "SAK: killed process %d"
>   			    " (%s): fd#%d opened to the tty\n",
>   				    task_pid_nr(p), p->comm, i - 1);
> -			force_sig(SIGKILL, p);
> +			send_sig(SIGKILL, p, 1);
>   		}
>   		task_unlock(p);
>   	} while_each_thread(g, p);
> 

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.