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authorPavel Begunkov <asml.silence@gmail.com>2021-01-26 15:28:27 +0000
committerJens Axboe <axboe@kernel.dk>2021-01-26 09:01:49 -0700
commitca70f00bed6cb255b7a9b91aa18a2717c9217f70 (patch)
treebabba64fe8c4f0ab97bbb535269d6a203de0fb54 /fs
parenta1bb3cd58913338e1b627ea6b8c03c2ae82d293f (diff)
downloadlinux-ca70f00bed6cb255b7a9b91aa18a2717c9217f70.tar.bz2
io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLE
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> [axboe: fix inverted task check] Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c39
1 files changed, 22 insertions, 17 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 09aada153a71..bb0270eeb8cb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8873,30 +8873,31 @@ 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)
+ cnt += io_match_task(req, task, files);
+ 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;
-
- 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);
+ int inflight;
- /* 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 +8906,11 @@ 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);
}
}