Re: [PATCH 2/8] kernel: unmask SIGSTOP for IO threads

Jens Axboe
2021-03-26T15:01:47Z

On 3/26/21 7:48 AM, Oleg Nesterov wrote:
> Jens, sorry, I got lost :/

Let's bring you back in :-)

> 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...

It's this very series.

>> 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.

Ah thanks.

> 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.

I do think the above is a no-op at this point, and we can probably just
kill it. Let me double check, hopefully we can just remove this blocked
part.

--
Jens Axboe