The patch titled
Subject: zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
zap_pid_ns_processes-clear-tif_notify_signal-along-with-tif_sigpending.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zap_pid_ns_processes-clear-tif_notify_signal-along-with-tif_sigpending.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING
Date: Sat, 8 Jun 2024 14:06:16 +0200
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@xxxxxxxxxx
Fixes: 12db8b690010 ("entry: Add support for TIF_NOTIFY_SIGNAL")
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reported-by: Rachel Menge <rachelmenge@xxxxxxxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/all/1386cd49-36d0-4a5c-85e9-bc42056a5a38@xxxxxxxxxxxxxxxxxxx/
Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Tested-By: Wei Fu <fuweid89@xxxxxxxxx>
Cc: Allen Pais <apais@xxxxxxxxxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Cc: Joel Granados <j.granados@xxxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Mateusz Guzik <mjguzik@xxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Mike Christie <michael.christie@xxxxxxxxxx>
Cc: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Zqiang <qiang.zhang1211@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/pid_namespace.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/pid_namespace.c~zap_pid_ns_processes-clear-tif_notify_signal-along-with-tif_sigpending
+++ a/kernel/pid_namespace.c
@@ -218,6 +218,7 @@ void zap_pid_ns_processes(struct pid_nam
*/
do {
clear_thread_flag(TIF_SIGPENDING);
+ clear_thread_flag(TIF_NOTIFY_SIGNAL);
rc = kernel_wait4(-1, NULL, __WALL, NULL);
} while (rc != -ECHILD);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
zap_pid_ns_processes-clear-tif_notify_signal-along-with-tif_sigpending.patch
zap_pid_ns_processes-dont-send-sigkill-to-sub-threads.patch
