| Message ID | 20201027100004.GA30670@tsappmail.ltts.com |
|---|---|
| State | New |
| Headers | show |
| Series | PM: Use WQ_MEM_RECLAIM flag for PM workqueue | expand |
On Tue, Oct 27, 2020 at 11:15 AM <ravisankarreddylingareddy@gmail.com> wrote: > > Deadlock is seen under below high memory usage scenario. I'm not sure what the "under below high" means. > kswapd waiting to reclaim memory is blocked on i/o kworker and pm_wq > context which needs to wakeup i/o kworker is waiting for kthread > creation which is again blocked in memory reclaim path. Can you explain in more detail how exactly you end up in that situation? > Use WQ_MEM_RECLAIM flag for PM workqueue to avoid this deadlock. This works, but this flag doesn't seem to be appropriate here, because pm_wq doesn't actually participate in memory reclaim. > Signed-off-by: Ravisankar Reddy (Sony) <ravisankarreddylingareddy@gmail.com> > --- > kernel/power/main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/power/main.c b/kernel/power/main.c > index 40f86ec4ab30..ff5f3349e76f 100644 > --- a/kernel/power/main.c > +++ b/kernel/power/main.c > @@ -933,7 +933,7 @@ EXPORT_SYMBOL_GPL(pm_wq); > > static int __init pm_start_workqueue(void) > { > - pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0); > + pm_wq = alloc_workqueue("pm", WQ_FREEZABLE | WQ_MEM_RECLAIM, 0); > > return pm_wq ? 0 : -ENOMEM; > } > -- > 2.17.1 >
diff --git a/kernel/power/main.c b/kernel/power/main.c index 40f86ec4ab30..ff5f3349e76f 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -933,7 +933,7 @@ EXPORT_SYMBOL_GPL(pm_wq); static int __init pm_start_workqueue(void) { - pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0); + pm_wq = alloc_workqueue("pm", WQ_FREEZABLE | WQ_MEM_RECLAIM, 0); return pm_wq ? 0 : -ENOMEM; }
Deadlock is seen under below high memory usage scenario. kswapd waiting to reclaim memory is blocked on i/o kworker and pm_wq context which needs to wakeup i/o kworker is waiting for kthread creation which is again blocked in memory reclaim path. Use WQ_MEM_RECLAIM flag for PM workqueue to avoid this deadlock. Signed-off-by: Ravisankar Reddy (Sony) <ravisankarreddylingareddy@gmail.com> --- kernel/power/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)