The patch titled Subject: freezer: do not send a fake signal to a PF_DUMPCORE thread has been added to the -mm tree. Its filename is freezer-do-not-send-a-fake-signal-to-a-pf_dumpcore-thread.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/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: freezer: do not send a fake signal to a PF_DUMPCORE thread A coredumping thread can't be frozen anyway but the fake signal sent by freeze_task() can confuse dump_write/wait_for_dump_helpers/etc and interrupt the coredump. We are going to make the do_coredump() paths freezable but the fake TIF_SIGPENDING doesn't help, it only makes sense when we assume that the target can return to user-mode and call get_signal_to_deliver(). Change freeze_task() to check PF_DUMPCORE along with PF_KTHREAD. We need to recheck PF_DUMPCORE under ->siglock to avoid the race with zap_threads() which can set this flag right before we take the lock. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Cc: Mandeep Singh Baines <msb@xxxxxxxxxxxx> Cc: Neil Horman <nhorman@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/freezer.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff -puN kernel/freezer.c~freezer-do-not-send-a-fake-signal-to-a-pf_dumpcore-thread kernel/freezer.c --- a/kernel/freezer.c~freezer-do-not-send-a-fake-signal-to-a-pf_dumpcore-thread +++ a/kernel/freezer.c @@ -85,14 +85,21 @@ bool __refrigerator(bool check_kthr_stop } EXPORT_SYMBOL(__refrigerator); -static void fake_signal_wake_up(struct task_struct *p) +static bool fake_signal_wake_up(struct task_struct *p) { unsigned long flags; + bool ret = false; + + if (p->flags & (PF_KTHREAD | PF_DUMPCORE)) + return ret; if (lock_task_sighand(p, &flags)) { - signal_wake_up(p, 0); + ret = !(p->flags & PF_DUMPCORE); + if (ret) + signal_wake_up(p, 0); unlock_task_sighand(p, &flags); } + return ret; } /** @@ -100,8 +107,8 @@ static void fake_signal_wake_up(struct t * @p: task to send the request to * * If @p is freezing, the freeze request is sent either by sending a fake - * signal (if it's not a kernel thread) or waking it up (if it's a kernel - * thread). + * signal (if it's not a kernel thread or a coredumping thread) or waking + * it up otherwise. * * RETURNS: * %false, if @p is not freezing or already frozen; %true, otherwise @@ -116,9 +123,7 @@ bool freeze_task(struct task_struct *p) return false; } - if (!(p->flags & PF_KTHREAD)) - fake_signal_wake_up(p); - else + if (!fake_signal_wake_up(p)) wake_up_state(p, TASK_INTERRUPTIBLE); spin_unlock_irqrestore(&freezer_lock, flags); _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch usermodehelper-cleanup-fix-__orderly_poweroff-argv_free.patch signal-allow-to-send-any-siginfo-to-itself.patch kernel-signalc-fix-suboptimal-printk-usage.patch coredump-only-sigkill-should-interrupt-the-coredumping-task.patch coredump-ensure-that-sigkill-always-kills-the-dumping-thread.patch coredump-sanitize-the-setting-of-signal-group_exit_code.patch coredump-factor-out-the-setting-of-pf_dumpcore.patch freezer-do-not-send-a-fake-signal-to-a-pf_dumpcore-thread.patch coredump-make-wait_for_dump_helpers-freezable.patch lockdep-check-that-no-locks-held-at-freeze-time.patch lockdep-check-that-no-locks-held-at-freeze-time-v2.patch lockdep-check-that-no-locks-held-at-freeze-time-fix.patch coredump-use-a-freezable_schedule-for-the-coredump_finish-wait.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html