syzbot fixes
Subsystems (3)
cover syzbot fixes
2/2 is a reincarnated issue found by syzbot, fixed by cancel-all-reqs patches before.
Pavel Begunkov (2):
io_uring: fix __io_uring_files_cancel() with TASK_UNINTERRUPTIBLE
io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLE
fs/io_uring.c | 52 ++++++++++++++++++++++++++++----------------------- 1 file changed, 29 insertions(+), 23 deletions(-)
Signature · 1 line
2.24.0
PATCH 1/2 io_uring: fix __io_uring_files_cancel() with TASK_UNINTERRUPTIBLE
If the tctx inflight number haven't changed because of cancellation, __io_uring_task_cancel() will continue leaving the task in TASK_UNINTERRUPTIBLE state, that's not expected by __io_uring_files_cancel(). Ensure we always call finish_wait() before retrying.
Cc [email protected] # 5.9+
Signed-off-by Pavel Begunkov <[email protected]>
--- fs/io_uring.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
fs/io_uring.c +5 -6
@@ -9124,16 +9124,15 @@ void __io_uring_task_cancel(void)prepare_to_wait (&tctx->wait, &wait,TASK_UNINTERRUPTIBLE );/* -* If we've seen completions, retry. This avoids a race where -* a completion comes in before we did prepare_to_wait(). +* If we've seen completions, retry without waiting. This +* avoids a race where a completion comes in before we did +* prepare_to_wait(). */ -if (inflight !=tctx_inflight (tctx)) -continue ; -schedule (); +if (inflight ==tctx_inflight (tctx)) +schedule ();finish_wait (&tctx->wait, &wait); }while (1 ); -finish_wait (&tctx->wait, &wait);atomic_dec (&tctx->in_idle);io_uring_remove_task_files (tctx);
Signature · 1 line
2.24.0
PATCH 2/2 io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLE
In reply to Pavel Begunkovdo not call blocking ops when !TASK_RUNNING; state=2 set at
[<00000000ced9dbfc>] prepare_to_wait+0x1f4/0x3b0 kernel/sched/wait.c:262 WARNING: CPU: 1 PID: 19888 at kernel/sched/core.c:7853 __might_sleep+0xed/0x100 kernel/sched/core.c:7848 RIP: 0010:__might_sleep+0xed/0x100 kernel/sched/core.c:7848 Call Trace: __mutex_lock_common+0xc4/0x2ef0 kernel/locking/mutex.c:935 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118 io_wq_submit_work+0x39a/0x720 fs/io_uring.c:6411 io_run_cancel fs/io-wq.c:856 [inline] io_wqe_cancel_pending_work fs/io-wq.c:990 [inline] io_wq_cancel_cb+0x614/0xcb0 fs/io-wq.c:1027 io_uring_cancel_files fs/io_uring.c:8874 [inline] io_uring_cancel_task_requests fs/io_uring.c:8952 [inline] __io_uring_files_cancel+0x115d/0x19e0 fs/io_uring.c:9038 io_uring_files_cancel include/linux/io_uring.h:51 [inline] do_exit+0x2e6/0x2490 kernel/exit.c:780 do_group_exit+0x168/0x2d0 kernel/exit.c:922 get_signal+0x16b5/0x2030 kernel/signal.c:2770 arch_do_signal_or_restart+0x8e/0x6a0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0xac/0x1e0 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x48/0x190 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Rewrite io_uring_cancel_files() to mimic __io_uring_task_cancel()'s counting scheme, so it does all the heavy work before setting TASK_UNINTERRUPTIBLE.
Cc [email protected] # 5.9+
Reported-by [email protected]
Signed-off-by Pavel Begunkov <[email protected]>
--- fs/io_uring.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-)
fs/io_uring.c +24 -17
@@ -8873,30 +8873,33 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx, } } +static int io_uring_count_inflight (struct io_ring_ctx *ctx, +struct task_struct *task, +struct files_struct *files) +{ +struct io_kiocb *req; +int cnt =0 ; + +spin_lock_irq (&ctx->inflight_lock); +list_for_each_entry (req, &ctx->inflight_list, inflight_entry) { +if (!io_match_task (req, task, files)) + cnt++; + } +spin_unlock_irq (&ctx->inflight_lock); +return cnt; +} +static void io_uring_cancel_files (struct io_ring_ctx *ctx,struct task_struct *task,struct files_struct *files) {while (!list_empty_careful (&ctx->inflight_list)) {struct io_task_cancel cancel = { .task = task, .files = files }; -struct io_kiocb *req;DEFINE_WAIT (wait); -bool found = false; +int inflight; -spin_lock_irq (&ctx->inflight_lock); -list_for_each_entry (req, &ctx->inflight_list, inflight_entry) { -if (!io_match_task (req, task, files)) -continue ; - found = true; -break ; - } -if (found) -prepare_to_wait (&task->io_uring->wait, &wait, -TASK_UNINTERRUPTIBLE ); -spin_unlock_irq (&ctx->inflight_lock); - -/* We need to keep going until we don't find a matching req */ -if (!found) + inflight =io_uring_count_inflight (ctx, task, files); +if (!inflight)break ;io_wq_cancel_cb (ctx->io_wq, io_cancel_task_cb, &cancel, true);
@@ -8905,7 +8908,11 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,io_cqring_overflow_flush (ctx, true, task, files);/* cancellations _may_ trigger task work */ io_run_task_work (); -schedule (); + +prepare_to_wait (&task->io_uring->wait, &wait, +TASK_UNINTERRUPTIBLE ); +if (inflight ==io_uring_count_inflight (ctx, task, files)) +schedule ();finish_wait (&task->io_uring->wait, &wait); } }
Signature · 1 line
2.24.0
Re: [PATCH 2/2] io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLE
Quoted 48 lines · Pavel Begunkov
do not call blocking ops when !TASK_RUNNING; state=2 set at
[<00000000ced9dbfc>] prepare_to_wait+0x1f4/0x3b0 kernel/sched/wait.c:262 WARNING: CPU: 1 PID: 19888 at kernel/sched/core.c:7853 __might_sleep+0xed/0x100 kernel/sched/core.c:7848 RIP: 0010:__might_sleep+0xed/0x100 kernel/sched/core.c:7848 Call Trace: __mutex_lock_common+0xc4/0x2ef0 kernel/locking/mutex.c:935 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118 io_wq_submit_work+0x39a/0x720 fs/io_uring.c:6411 io_run_cancel fs/io-wq.c:856 [inline] io_wqe_cancel_pending_work fs/io-wq.c:990 [inline] io_wq_cancel_cb+0x614/0xcb0 fs/io-wq.c:1027 io_uring_cancel_files fs/io_uring.c:8874 [inline] io_uring_cancel_task_requests fs/io_uring.c:8952 [inline] __io_uring_files_cancel+0x115d/0x19e0 fs/io_uring.c:9038 io_uring_files_cancel include/linux/io_uring.h:51 [inline] do_exit+0x2e6/0x2490 kernel/exit.c:780 do_group_exit+0x168/0x2d0 kernel/exit.c:922 get_signal+0x16b5/0x2030 kernel/signal.c:2770 arch_do_signal_or_restart+0x8e/0x6a0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0xac/0x1e0 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x48/0x190 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9Rewrite
io_uring_cancel_files()to mimic __io_uring_task_cancel()'s counting scheme, so it does all the heavy work before settingTASK_UNINTERRUPTIBLE.Cc [email protected] # 5.9+Reported-by [email protected]Signed-off-by Pavel Begunkov <[email protected]>--- fs/io_uring.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-)fs/io_uring.c +0
-0@@ -8873,30 +8873,33 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx, } }
fs/io_uring.c static void io_cancel_defer_files(struct io_ring_ctx *ctx, · line 8885
Quoted 10 lines
fs/io_uring.c +10
-0+static int io_uring_count_inflight (struct io_ring_ctx *ctx, +struct task_struct *task, +struct files_struct *files) +{ +struct io_kiocb *req; +int cnt =0 ; + +spin_lock_irq (&ctx->inflight_lock); +list_for_each_entry (req, &ctx->inflight_list, inflight_entry) { +if (!io_match_task (req, task, files))
This condition should be inversed. Jens, please drop it
p.s. I wonder how tests didn't catch that
Quoted 50 lines
fs/io_uring.c +14
-17+ cnt++; + } +spin_unlock_irq (&ctx->inflight_lock); +return cnt; +} +static void io_uring_cancel_files (struct io_ring_ctx *ctx,struct task_struct *task,struct files_struct *files) {while (!list_empty_careful (&ctx->inflight_list)) {struct io_task_cancel cancel = { .task = task, .files = files }; -struct io_kiocb *req;DEFINE_WAIT (wait); -bool found = false; +int inflight; -spin_lock_irq (&ctx->inflight_lock); -list_for_each_entry (req, &ctx->inflight_list, inflight_entry) { -if (!io_match_task (req, task, files)) -continue ; - found = true; -break ; - } -if (found) -prepare_to_wait (&task->io_uring->wait, &wait, -TASK_UNINTERRUPTIBLE ); -spin_unlock_irq (&ctx->inflight_lock); - -/* We need to keep going until we don't find a matching req */ -if (!found) + inflight =io_uring_count_inflight (ctx, task, files); +if (!inflight)break ;io_wq_cancel_cb (ctx->io_wq, io_cancel_task_cb, &cancel, true);@@ -8905,7 +8908,11 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,io_cqring_overflow_flush (ctx, true, task, files);/* cancellations _may_ trigger task work */ io_run_task_work (); -schedule (); + +prepare_to_wait (&task->io_uring->wait, &wait, +TASK_UNINTERRUPTIBLE ); +if (inflight ==io_uring_count_inflight (ctx, task, files)) +schedule ();finish_wait (&task->io_uring->wait, &wait); } }
Signature · 1 line
Pavel Begunkov
Jens Axboe
maintainerRe: [PATCH 2/2] io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLE
Quoted 62 lines · Pavel Begunkov
Quoted 48 lines · Pavel Begunkov
do not call blocking ops when !TASK_RUNNING; state=2 set at
[<00000000ced9dbfc>] prepare_to_wait+0x1f4/0x3b0 kernel/sched/wait.c:262 WARNING: CPU: 1 PID: 19888 at kernel/sched/core.c:7853 __might_sleep+0xed/0x100 kernel/sched/core.c:7848 RIP: 0010:__might_sleep+0xed/0x100 kernel/sched/core.c:7848 Call Trace: __mutex_lock_common+0xc4/0x2ef0 kernel/locking/mutex.c:935 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118 io_wq_submit_work+0x39a/0x720 fs/io_uring.c:6411 io_run_cancel fs/io-wq.c:856 [inline] io_wqe_cancel_pending_work fs/io-wq.c:990 [inline] io_wq_cancel_cb+0x614/0xcb0 fs/io-wq.c:1027 io_uring_cancel_files fs/io_uring.c:8874 [inline] io_uring_cancel_task_requests fs/io_uring.c:8952 [inline] __io_uring_files_cancel+0x115d/0x19e0 fs/io_uring.c:9038 io_uring_files_cancel include/linux/io_uring.h:51 [inline] do_exit+0x2e6/0x2490 kernel/exit.c:780 do_group_exit+0x168/0x2d0 kernel/exit.c:922 get_signal+0x16b5/0x2030 kernel/signal.c:2770 arch_do_signal_or_restart+0x8e/0x6a0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0xac/0x1e0 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x48/0x190 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9Rewrite
io_uring_cancel_files()to mimic __io_uring_task_cancel()'s counting scheme, so it does all the heavy work before settingTASK_UNINTERRUPTIBLE.Cc [email protected] # 5.9+Reported-by [email protected]Signed-off-by Pavel Begunkov <[email protected]>--- fs/io_uring.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-)fs/io_uring.c +0
-0@@ -8873,30 +8873,33 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx, } }fs/io_uring.c static void io_cancel_defer_files(struct io_ring_ctx *ctx, · line 8885
Quoted 10 lines
fs/io_uring.c +10
-0+static int io_uring_count_inflight (struct io_ring_ctx *ctx, +struct task_struct *task, +struct files_struct *files) +{ +struct io_kiocb *req; +int cnt =0 ; + +spin_lock_irq (&ctx->inflight_lock); +list_for_each_entry (req, &ctx->inflight_list, inflight_entry) { +if (!io_match_task (req, task, files))This condition should be inversed. Jens, please drop it
Quoted 1 line
p.s. I wonder how tests didn't catch that
Probably just make it cnt += io_match_task(req, task_files) to simplify it. But yes, it looks reversed.
Signature · 1 line
Jens Axboe
Jens Axboe
maintainerQuoted 9 lines · Pavel Begunkov
2/2 is a reincarnated issue found by syzbot, fixed by cancel-all-reqs patches before.
Pavel Begunkov (2):
io_uring: fix__io_uring_files_cancel()withTASK_UNINTERRUPTIBLE
io_uring: fix cancellation taking mutex whileTASK_UNINTERRUPTIBLEfs/io_uring.c | 52 ++++++++++++++++++++++++++++----------------------- 1 file changed, 29 insertions(+), 23 deletions(-)
LGTM, applied.
Signature · 1 line
Jens Axboe