mirror of
https://github.com/raspberrypi/linux.git
synced 2025-12-09 11:30:02 +00:00
b88f55389a
The kernel sleep profile is no longer working due to a recursive locking bug introduced by commit42a20f86dc("sched: Add wrapper for get_wchan() to keep task blocked") Booting with the 'profile=sleep' kernel command line option added or executing # echo -n sleep > /sys/kernel/profiling after boot causes the system to lock up. Lockdep reports kthreadd/3 is trying to acquire lock: ffff93ac82e08d58 (&p->pi_lock){....}-{2:2}, at: get_wchan+0x32/0x70 but task is already holding lock: ffff93ac82e08d58 (&p->pi_lock){....}-{2:2}, at: try_to_wake_up+0x53/0x370 with the call trace being lock_acquire+0xc8/0x2f0 get_wchan+0x32/0x70 __update_stats_enqueue_sleeper+0x151/0x430 enqueue_entity+0x4b0/0x520 enqueue_task_fair+0x92/0x6b0 ttwu_do_activate+0x73/0x140 try_to_wake_up+0x213/0x370 swake_up_locked+0x20/0x50 complete+0x2f/0x40 kthread+0xfb/0x180 However, since nobody noticed this regression for more than two years, let's remove 'profile=sleep' support based on the assumption that nobody needs this functionality. Fixes:42a20f86dc("sched: Add wrapper for get_wchan() to keep task blocked") Cc: stable@vger.kernel.org # v5.16+ Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>