From 8e69e589f233ca2c9631f5af2b94f95dfc2ba804 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 8 Jun 2024 14:06:16 +0200 Subject: [PATCH] zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING [ Upstream commit 7fea700e04bd3f424c2d836e98425782f97b494e ] kernel_wait4() doesn't sleep and returns -EINTR if there is no eligible child and signal_pending() is true. That is why zap_pid_ns_processes() clears TIF_SIGPENDING but this is not enough, it should also clear TIF_NOTIFY_SIGNAL to make signal_pending() return false and avoid a busy-wait loop. Link: https://lkml.kernel.org/r/20240608120616.GB7947@redhat.com Fixes: 12db8b690010 ("entry: Add support for TIF_NOTIFY_SIGNAL") Signed-off-by: Oleg Nesterov Reported-by: Rachel Menge Closes: https://lore.kernel.org/all/1386cd49-36d0-4a5c-85e9-bc42056a5a38@linux.microsoft.com/ Reviewed-by: Boqun Feng Tested-by: Wei Fu Reviewed-by: Jens Axboe Cc: Allen Pais Cc: Christian Brauner Cc: Frederic Weisbecker Cc: Joel Fernandes (Google) Cc: Joel Granados Cc: Josh Triplett Cc: Lai Jiangshan Cc: Mateusz Guzik Cc: Mathieu Desnoyers Cc: Mike Christie Cc: Neeraj Upadhyay Cc: Paul E. McKenney Cc: Steven Rostedt (Google) Cc: Zqiang Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/pid_namespace.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 259fc4ca0d9c..40b011f88067 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -214,6 +214,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) */ do { clear_thread_flag(TIF_SIGPENDING); + clear_thread_flag(TIF_NOTIFY_SIGNAL); rc = kernel_wait4(-1, NULL, __WALL, NULL); } while (rc != -ECHILD);