io_uring: ensure that threads freeze on suspend

Alex reports that his system fails to suspend using 5.12-rc1, with the following dump: [ 240.650300] PM: suspend entry (deep) [ 240.650748] Filesystems sync: 0.000 seconds [ 240.725605] Freezing user space processes ... [ 260.739483] Freezing of tasks failed after 20.013 seconds (3 tasks refusing to freeze, wq_busy=0): [ 260.739497] task:iou-mgr-446 state:S stack: 0 pid: 516 ppid: 439 flags:0x00004224 [ 260.739504] Call Trace: [ 260.739507] ? sysvec_apic_timer_interrupt+0xb/0x81 [ 260.739515] ? pick_next_task_fair+0x197/0x1cde [ 260.739519] ? sysvec_reschedule_ipi+0x2f/0x6a [ 260.739522] ? asm_sysvec_reschedule_ipi+0x12/0x20 [ 260.739525] ? __schedule+0x57/0x6d6 [ 260.739529] ? del_timer_sync+0xb9/0x115 [ 260.739533] ? schedule+0x63/0xd5 [ 260.739536] ? schedule_timeout+0x219/0x356 [ 260.739540] ? __next_timer_interrupt+0xf1/0xf1 [ 260.739544] ? io_wq_manager+0x73/0xb1 [ 260.739549] ? io_wq_create+0x262/0x262 [ 260.739553] ? ret_from_fork+0x22/0x30 [ 260.739557] task:iou-mgr-517 state:S stack: 0 pid: 522 ppid: 439 flags:0x00004224 [ 260.739561] Call Trace: [ 260.739563] ? sysvec_apic_timer_interrupt+0xb/0x81 [ 260.739566] ? pick_next_task_fair+0x16f/0x1cde [ 260.739569] ? sysvec_apic_timer_interrupt+0xb/0x81 [ 260.739571] ? asm_sysvec_apic_timer_interrupt+0x12/0x20 [ 260.739574] ? __schedule+0x5b7/0x6d6 [ 260.739578] ? del_timer_sync+0x70/0x115 [ 260.739581] ? schedule_timeout+0x211/0x356 [ 260.739585] ? __next_timer_interrupt+0xf1/0xf1 [ 260.739588] ? io_wq_check_workers+0x15/0x11f [ 260.739592] ? io_wq_manager+0x69/0xb1 [ 260.739596] ? io_wq_create+0x262/0x262 [ 260.739600] ? ret_from_fork+0x22/0x30 [ 260.739603] task:iou-wrk-517 state:S stack: 0 pid: 523 ppid: 439 flags:0x00004224 [ 260.739607] Call Trace: [ 260.739609] ? __schedule+0x5b7/0x6d6 [ 260.739614] ? schedule+0x63/0xd5 [ 260.739617] ? schedule_timeout+0x219/0x356 [ 260.739621] ? __next_timer_interrupt+0xf1/0xf1 [ 260.739624] ? task_thread.isra.0+0x148/0x3af [ 260.739628] ? task_thread_unbound+0xa/0xa [ 260.739632] ? task_thread_bound+0x7/0x7 [ 260.739636] ? ret_from_fork+0x22/0x30 [ 260.739647] OOM killer enabled. [ 260.739648] Restarting tasks ... done. [ 260.740077] PM: suspend exit Play nice and ensure that any thread we create will call try_to_freeze() at an opportune time so that memory suspend can proceed. For the io-wq worker threads, mark them as PF_NOFREEZE. They could potentially be blocked for a long time. Reported-by: Alex Xu (Hello71) <[email protected]> Tested-by: Alex Xu (Hello71) <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
josf · Mar 4, 2021 · e4b4a13 · e4b4a13
1 parent b23fcf4
commit e4b4a13
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/fs/io-wq.c b/fs/io-wq.c
@@ -16,6 +16,7 @@
 #include <linux/rculist_nulls.h>
 #include <linux/cpu.h>
 #include <linux/tracehook.h>
+#include <linux/freezer.h>
 
 #include "../kernel/sched/sched.h"
 #include "io-wq.h"
@@ -263,6 +264,7 @@ static void io_wqe_dec_running(struct io_worker *worker)
 
 static void io_worker_start(struct io_worker *worker)
 {
+	current->flags |= PF_NOFREEZE;
 	worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
 	io_wqe_inc_running(worker);
 	complete(&worker->started);
@@ -731,6 +733,7 @@ static int io_wq_manager(void *data)
 		set_current_state(TASK_INTERRUPTIBLE);
 		io_wq_check_workers(wq);
 		schedule_timeout(HZ);
+		try_to_freeze();
 		if (fatal_signal_pending(current))
 			set_bit(IO_WQ_BIT_EXIT, &wq->state);
 	} while (!test_bit(IO_WQ_BIT_EXIT, &wq->state));

diff --git a/fs/io_uring.c b/fs/io_uring.c
@@ -74,13 +74,11 @@
 #include <linux/fsnotify.h>
 #include <linux/fadvise.h>
 #include <linux/eventpoll.h>
-#include <linux/fs_struct.h>
 #include <linux/splice.h>
 #include <linux/task_work.h>
 #include <linux/pagemap.h>
 #include <linux/io_uring.h>
-#include <linux/blk-cgroup.h>
-#include <linux/audit.h>
+#include <linux/freezer.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
@@ -6736,6 +6734,7 @@ static int io_sq_thread(void *data)
 				io_ring_set_wakeup_flag(ctx);
 
 			schedule();
+			try_to_freeze();
 			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
 				io_ring_clear_wakeup_flag(ctx);
 		}