summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJens Axboe <axboe@kernel.dk>2021-02-28 15:32:18 -0700
committerJens Axboe <axboe@kernel.dk>2021-03-04 06:37:14 -0700
commit3ebba796fa251d042be42b929a2d916ee5c34a49 (patch)
tree96b80f50ec7cdcb297a6e1c317ae1455fc8dede2
parent28c4721b80a702462fb77373c23428ee698fa5dd (diff)
io_uring: ensure that SQPOLL thread is started for exit
If we create it in a disabled state because IORING_SETUP_R_DISABLED is set on ring creation, we need to ensure that we've kicked the thread if we're exiting before it's been explicitly disabled. Otherwise we can run into a deadlock where exit is waiting go park the SQPOLL thread, but the SQPOLL thread itself is waiting to get a signal to start. That results in the below trace of both tasks hung, waiting on each other: INFO: task syz-executor458:8401 blocked for more than 143 seconds. Not tainted 5.11.0-next-20210226-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor458 state:D stack:27536 pid: 8401 ppid: 8400 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4324 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5075 schedule+0xcf/0x270 kernel/sched/core.c:5154 schedule_timeout+0x1db/0x250 kernel/time/timer.c:1868 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x168/0x270 kernel/sched/completion.c:138 io_sq_thread_park fs/io_uring.c:7115 [inline] io_sq_thread_park+0xd5/0x130 fs/io_uring.c:7103 io_uring_cancel_task_requests+0x24c/0xd90 fs/io_uring.c:8745 __io_uring_files_cancel+0x110/0x230 fs/io_uring.c:8840 io_uring_files_cancel include/linux/io_uring.h:47 [inline] do_exit+0x299/0x2a60 kernel/exit.c:780 do_group_exit+0x125/0x310 kernel/exit.c:922 __do_sys_exit_group kernel/exit.c:933 [inline] __se_sys_exit_group kernel/exit.c:931 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x43e899 RSP: 002b:00007ffe89376d48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00000000004af2f0 RCX: 000000000043e899 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000010000000 R10: 0000000000008011 R11: 0000000000000246 R12: 00000000004af2f0 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 INFO: task iou-sqp-8401:8402 can't die for more than 143 seconds. task:iou-sqp-8401 state:D stack:30272 pid: 8402 ppid: 8400 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4324 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5075 schedule+0xcf/0x270 kernel/sched/core.c:5154 schedule_timeout+0x1db/0x250 kernel/time/timer.c:1868 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x168/0x270 kernel/sched/completion.c:138 io_sq_thread+0x27d/0x1ae0 fs/io_uring.c:6717 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 INFO: task iou-sqp-8401:8402 blocked for more than 143 seconds. Reported-by: syzbot+fb5458330b4442f2090d@syzkaller.appspotmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 57c7833ba62b..94b1a0f48fed 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7916,6 +7916,7 @@ static void io_sq_offload_start(struct io_ring_ctx *ctx)
{
struct io_sq_data *sqd = ctx->sq_data;
+ ctx->flags &= ~IORING_SETUP_R_DISABLED;
if (ctx->flags & IORING_SETUP_SQPOLL)
complete(&sqd->startup);
}
@@ -8692,6 +8693,8 @@ static void io_disable_sqo_submit(struct io_ring_ctx *ctx)
{
mutex_lock(&ctx->uring_lock);
ctx->sqo_dead = 1;
+ if (ctx->flags & IORING_SETUP_R_DISABLED)
+ io_sq_offload_start(ctx);
mutex_unlock(&ctx->uring_lock);
/* make sure callers enter the ring to get error */
@@ -9637,10 +9640,7 @@ static int io_register_enable_rings(struct io_ring_ctx *ctx)
if (ctx->restrictions.registered)
ctx->restricted = 1;
- ctx->flags &= ~IORING_SETUP_R_DISABLED;
-
io_sq_offload_start(ctx);
-
return 0;
}