On 26/01/2021 15:28, Pavel Begunkov wrote:
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+0x44/0xa9
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: stable@vger.kernel.org # 5.9+ Reported-by: syzbot+f655445043a26a7cfab8@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com
fs/io_uring.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 09aada153a71..f3f2b37e7021 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -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))
This condition should be inversed. Jens, please drop it
p.s. I wonder how tests didn't catch that
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;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();}