From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>,
[email protected], Oleg Nesterov <[email protected]>,
Andrew Morton <[email protected]>,
Christian Brauner <[email protected]>,
Tycho Andersen <[email protected]>,
Thomas Gleixner <[email protected]>,
[email protected], Julian Orth <[email protected]>,
Peter Zijlstra <[email protected]>, Tejun Heo <[email protected]>
Subject: [PATCH v2 2/2] kernel: rerun task_work while freezing in get_signal()
Date: Tue, 9 Jul 2024 15:27:19 +0100 [thread overview]
Message-ID: <149ff5a762997c723880751e8a4019907a0b6457.1720534425.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>
io_uring can asynchronously add a task_work while the task is getting
freezed. TIF_NOTIFY_SIGNAL will prevent the task from sleeping in
do_freezer_trap(), and since the get_signal()'s relock loop doesn't
retry task_work, the task will spin there not being able to sleep
until the freezing is cancelled / the task is killed / etc.
Cc: [email protected]
Link: https://github.com/systemd/systemd/issues/33626
Fixes: 12db8b690010c ("entry: Add support for TIF_NOTIFY_SIGNAL")
Reported-by: Julian Orth <[email protected]>
Signed-off-by: Pavel Begunkov <[email protected]>
---
kernel/signal.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/signal.c b/kernel/signal.c
index 1f9dd41c04be..60c737e423a1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2600,6 +2600,14 @@ static void do_freezer_trap(void)
spin_unlock_irq(¤t->sighand->siglock);
cgroup_enter_frozen();
schedule();
+
+ /*
+ * We could've been woken by task_work, run it to clear
+ * TIF_NOTIFY_SIGNAL. The caller will retry if necessary.
+ */
+ clear_notify_signal();
+ if (unlikely(task_work_pending(current)))
+ task_work_run();
}
static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
--
2.44.0
next prev parent reply other threads:[~2024-07-09 14:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-09 14:27 [PATCH v2 0/2] fix task_work interation with freezing Pavel Begunkov
2024-07-09 14:27 ` [PATCH v2 1/2] io_uring/io-wq: limit retrying worker initialisation Pavel Begunkov
2024-07-09 14:27 ` Pavel Begunkov [this message]
2024-07-09 14:42 ` [PATCH v2 2/2] kernel: rerun task_work while freezing in get_signal() Oleg Nesterov
2024-07-10 0:57 ` Tejun Heo
2024-07-10 17:55 ` Pavel Begunkov
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