Andrew are you still planning to push this comment fix upstream? Eric Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > The patch titled > Subject: kthread: make it clear that kthread_create_on_node() might be terminated by any fatal signal > has been added to the -mm tree. Its filename is > kthread-make-it-clear-that-kthread_create_on_node-might-be-terminated-by-any-fatal-signal.patch > > This patch should soon appear at > https://ozlabs.org/~akpm/mmots/broken-out/kthread-make-it-clear-that-kthread_create_on_node-might-be-terminated-by-any-fatal-signal.patch > and later at > https://ozlabs.org/~akpm/mmotm/broken-out/kthread-make-it-clear-that-kthread_create_on_node-might-be-terminated-by-any-fatal-signal.patch > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** > > The -mm tree is included into linux-next and is updated > there every 3-4 working days > > ------------------------------------------------------ > From: Petr Mladek <pmladek@xxxxxxxx> > Subject: kthread: make it clear that kthread_create_on_node() might be terminated by any fatal signal > > The comments in kernel/kthread.c create a feeling that only SIGKILL is > able to terminate the creation of kernel kthreads by > kthread_create()/_on_node()/_on_cpu() APIs. > > In reality, wait_for_completion_killable() might be killed by any fatal > signal that does not have a custom handler: > > (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \ > (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL) > > static inline void signal_wake_up(struct task_struct *t, bool resume) > { > signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0); > } > > static void complete_signal(int sig, struct task_struct *p, enum pid_type type) > { > [...] > /* > * Found a killable thread. If the signal will be fatal, > * then start taking the whole group down immediately. > */ > if (sig_fatal(p, sig) ...) { > if (!sig_kernel_coredump(sig)) { > [...] > do { > task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); > sigaddset(&t->pending.signal, SIGKILL); > signal_wake_up(t, 1); > } while_each_thread(p, t); > return; > } > } > } > > Update the comments in kernel/kthread.c to make this more obvious. > > The motivation for this change was debugging why a module initialization > failed. The module was being loaded from initrd. It "magically" failed > when systemd was switching to the real root. The clean up operations sent > SIGTERM to various pending processed that were started from initrd. > > Link: https://lkml.kernel.org/r/20220315102444.2380-1-pmladek@xxxxxxxx > Signed-off-by: Petr Mladek <pmladek@xxxxxxxx> > Reviewed-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: Marco Elver <elver@xxxxxxxxxx> > Cc: Jens Axboe <axboe@xxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > kernel/kthread.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > --- a/kernel/kthread.c~kthread-make-it-clear-that-kthread_create_on_node-might-be-terminated-by-any-fatal-signal > +++ a/kernel/kthread.c > @@ -341,7 +341,7 @@ static int kthread(void *_create) > > self = to_kthread(current); > > - /* If user was SIGKILLed, I release the structure. */ > + /* Release the structure when caller killed by a fatal signal. */ > done = xchg(&create->done, NULL); > if (!done) { > kfree(create); > @@ -399,7 +399,7 @@ static void create_kthread(struct kthrea > /* We want our own signal handler (we take no signals by default). */ > pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); > if (pid < 0) { > - /* If user was SIGKILLed, I release the structure. */ > + /* Release the structure when caller killed by a fatal signal. */ > struct completion *done = xchg(&create->done, NULL); > > if (!done) { > @@ -441,9 +441,9 @@ struct task_struct *__kthread_create_on_ > */ > if (unlikely(wait_for_completion_killable(&done))) { > /* > - * If I was SIGKILLed before kthreadd (or new kernel thread) > - * calls complete(), leave the cleanup of this structure to > - * that thread. > + * If I was killed by a fatal signal before kthreadd (or new > + * kernel thread) calls complete(), leave the cleanup of this > + * structure to that thread. > */ > if (xchg(&create->done, NULL)) > return ERR_PTR(-EINTR); > @@ -877,7 +877,7 @@ fail_task: > * > * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) > * when the needed structures could not get allocated, and ERR_PTR(-EINTR) > - * when the worker was SIGKILLed. > + * when the caller was killed by a fatal signal. > */ > struct kthread_worker * > kthread_create_worker(unsigned int flags, const char namefmt[], ...) > @@ -926,7 +926,7 @@ EXPORT_SYMBOL(kthread_create_worker); > * Return: > * The pointer to the allocated worker on success, ERR_PTR(-ENOMEM) > * when the needed structures could not get allocated, and ERR_PTR(-EINTR) > - * when the worker was SIGKILLed. > + * when the caller was killed by a fatal signal. > */ > struct kthread_worker * > kthread_create_worker_on_cpu(int cpu, unsigned int flags, > _ > > Patches currently in -mm which might be from pmladek@xxxxxxxx are > > kthread-make-it-clear-that-kthread_create_on_node-might-be-terminated-by-any-fatal-signal.patch
