From b16b3855d89fba640996fefdd3a113c0aa0e380d Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 26 Mar 2021 09:05:22 -0600 Subject: kernel: stop masking signals in create_io_thread() This is racy - move the blocking into when the task is created and we're marking it as PF_IO_WORKER anyway. The IO threads are now prepared to handle signals like SIGSTOP as well, so clear that from the mask to allow proper stopping of IO threads. Acked-by: "Eric W. Biederman" Reported-by: Oleg Nesterov Signed-off-by: Jens Axboe --- kernel/fork.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index d3171e8e88e5..ddaa15227071 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1940,8 +1940,14 @@ static __latent_entropy struct task_struct *copy_process( p = dup_task_struct(current, node); if (!p) goto fork_out; - if (args->io_thread) + if (args->io_thread) { + /* + * Mark us an IO worker, and block any signal that isn't + * fatal or STOP + */ p->flags |= PF_IO_WORKER; + siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)); + } /* * This _must_ happen before we call free_task(), i.e. before we jump @@ -2430,14 +2436,8 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) .stack_size = (unsigned long)arg, .io_thread = 1, }; - struct task_struct *tsk; - tsk = copy_process(NULL, 0, node, &args); - if (!IS_ERR(tsk)) { - sigfillset(&tsk->blocked); - sigdelsetmask(&tsk->blocked, sigmask(SIGKILL)); - } - return tsk; + return copy_process(NULL, 0, node, &args); } /* -- cgit v1.2.3-59-g8ed1b