From e4b4a13f494120c475580927864cc1dd96f595d1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 1 Mar 2021 18:36:25 -0700 Subject: [PATCH] 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) Tested-by: Alex Xu (Hello71) Signed-off-by: Jens Axboe --- fs/io-wq.c | 3 +++ fs/io_uring.c | 5 ++--- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/io-wq.c b/fs/io-wq.c index dc43038..acffc85 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -16,6 +16,7 @@ #include #include #include +#include #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 index 26e83ca..b1734ef 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -74,13 +74,11 @@ #include #include #include -#include #include #include #include #include -#include -#include +#include #define CREATE_TRACE_POINTS #include @@ -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); } -- 2.7.4