Commit b5dd2f6047ca1080 ("block: loop: improve performance via blk-mq")
started using a global WQ_MEM_RECLAIM workqueue.
+ loop_wq = alloc_workqueue("kloopd",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);
Commit f4aa4c7bbac6c4af ("block: loop: convert to per-device workqueue")
started using per device WQ_MEM_RECLAIM workqueue.
- loop_wq = alloc_workqueue("kloopd",
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);
+ lo->wq = alloc_workqueue("kloopd%d",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0,
+ lo->lo_number);
Commit 4d4e41aef9429872 ("block: loop: avoiding too many pending per work
I/O") adjusted max_active parameter.
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0,
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16,
Commit e03a3d7a94e2485b ("block: loop: use kthread_work") started using
per device kthread.
- lo->wq = alloc_workqueue("kloopd%d",
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16,
- lo->lo_number);
+ lo->worker_task = kthread_run(kthread_worker_fn,
+ &lo->worker, "loop%d", lo->lo_number);
Commit 87579e9b7d8dc36e ("loop: use worker per cgroup instead of kworker")
again started using per device workqueue
- lo->worker_task = kthread_run(loop_kthread_worker_fn,
- &lo->worker, "loop%d", lo->lo_number);
+ lo->workqueue = alloc_workqueue("loop%d",
+ WQ_UNBOUND | WQ_FREEZABLE,
+ 0,
+ lo->lo_number);
but forgot to restore WQ_MEM_RECLAIM flag.
We should reserve one "struct task_struct" to each loop device in order
to guarantee that I/O request for writeback operation can make forward
progress even under memory pressure. I don't know why WQ_FREEZABLE flag
was added, but let's add WQ_MEM_RECLAIM flag like commit f4aa4c7bbac6c4af
("block: loop: convert to per-device workqueue") describes.
Fixes: 87579e9b7d8dc36e ("loop: use worker per cgroup instead of kworker")
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/loop.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 19fe19eaa50e..60dfebcedd95 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1013,7 +1013,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
lo->lo_flags |= LO_FLAGS_READ_ONLY;
lo->workqueue = alloc_workqueue("loop%d",
- WQ_UNBOUND | WQ_FREEZABLE,
+ WQ_MEM_RECLAIM | WQ_UNBOUND | WQ_FREEZABLE,
0,
lo->lo_number);
if (!lo->workqueue) {
--
2.32.0
