4.14.109-rt58-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Scott Wood <swood@xxxxxxxxxx> [ Upstream commit 0d5d32425a0cab4a282dd79fc953d76a3ab17072 ] __down_read() bypasses the rtmutex frontend to call rt_mutex_slowlock_locked() directly, and thus it needs to call blk_schedule_flush_flug() itself. Cc: stable-rt@xxxxxxxxxxxxxxx Signed-off-by: Scott Wood <swood@xxxxxxxxxx> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx> Conflicts: kernel/locking/rwsem-rt.c --- kernel/locking/rtmutex.c | 2 +- kernel/locking/rwsem-rt.c | 9 +++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 2cf515877b8e..1177f2815040 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1946,7 +1946,7 @@ rt_mutex_fastlock(struct rt_mutex *lock, int state, * If rt_mutex blocks, the function sched_submit_work will not call * blk_schedule_flush_plug (because tsk_is_pi_blocked would be true). * We must call blk_schedule_flush_plug here, if we don't call it, - * a deadlock in device mapper may happen. + * a deadlock in I/O may happen. */ if (unlikely(blk_needs_flush_plug(current))) blk_schedule_flush_plug(current); diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c index 26991ddb6c5a..dbdde2476b1c 100644 --- a/kernel/locking/rwsem-rt.c +++ b/kernel/locking/rwsem-rt.c @@ -1,5 +1,6 @@ /* */ +#include <linux/blkdev.h> #include <linux/rwsem.h> #include <linux/sched/debug.h> #include <linux/sched/signal.h> @@ -86,6 +87,14 @@ void __sched __down_read(struct rw_semaphore *sem) if (__down_read_trylock(sem)) return; + /* + * If rt_mutex blocks, the function sched_submit_work will not call + * blk_schedule_flush_plug (because tsk_is_pi_blocked would be true). + * We must call blk_schedule_flush_plug here, if we don't call it, + * a deadlock in I/O may happen. + */ + if (unlikely(blk_needs_flush_plug(current))) + blk_schedule_flush_plug(current); might_sleep(); raw_spin_lock_irq(&m->wait_lock); -- 2.14.1
