* [PATCH 1/2] io_uring: cancel files inflight counting
2021-02-10 11:45 [PATCH 0/2] SQPOLL cancel files fix Pavel Begunkov
@ 2021-02-10 11:45 ` Pavel Begunkov
2021-02-10 11:45 ` [PATCH 2/2] io_uring; fix files cancel hangs Pavel Begunkov
2021-02-10 20:30 ` [PATCH 0/2] SQPOLL cancel files fix Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Pavel Begunkov @ 2021-02-10 11:45 UTC (permalink / raw)
To: Jens Axboe, io-uring
To not skip events, io_uring_cancel_files() is pretty much counts on
io_uring_count_inflight() to be monotonous for the time it's used.
That's not the case when it includes requests of other thats that are
PF_EXITING.
Cancel as before, but don't account extra in io_uring_count_inflight(),
we can hang otherwise.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 17194e0d62ff..6b73e38aa1a9 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1090,15 +1090,14 @@ static inline void io_set_resource_node(struct io_kiocb *req)
}
}
-static bool io_match_task(struct io_kiocb *head,
- struct task_struct *task,
- struct files_struct *files)
+static bool __io_match_task(struct io_kiocb *head, struct task_struct *task,
+ struct files_struct *files, bool match_exiting)
{
struct io_kiocb *req;
if (task && head->task != task) {
/* in terms of cancelation, always match if req task is dead */
- if (head->task->flags & PF_EXITING)
+ if (match_exiting && (head->task->flags & PF_EXITING))
return true;
return false;
}
@@ -1117,6 +1116,13 @@ static bool io_match_task(struct io_kiocb *head,
return false;
}
+static bool io_match_task(struct io_kiocb *head,
+ struct task_struct *task,
+ struct files_struct *files)
+{
+ return __io_match_task(head, task, files, true);
+}
+
static void io_sq_thread_drop_mm_files(void)
{
struct files_struct *files = current->files;
@@ -9032,7 +9038,7 @@ static int io_uring_count_inflight(struct io_ring_ctx *ctx,
spin_lock_irq(&ctx->inflight_lock);
list_for_each_entry(req, &ctx->inflight_list, inflight_entry)
- cnt += io_match_task(req, task, files);
+ cnt += __io_match_task(req, task, files, false);
spin_unlock_irq(&ctx->inflight_lock);
return cnt;
}
--
2.24.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] io_uring; fix files cancel hangs
2021-02-10 11:45 [PATCH 0/2] SQPOLL cancel files fix Pavel Begunkov
2021-02-10 11:45 ` [PATCH 1/2] io_uring: cancel files inflight counting Pavel Begunkov
@ 2021-02-10 11:45 ` Pavel Begunkov
2021-02-10 20:30 ` [PATCH 0/2] SQPOLL cancel files fix Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Pavel Begunkov @ 2021-02-10 11:45 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: stable, syzbot+695b03d82fa8e4901b06
We park SQPOLL task before going into io_uring_cancel_files(), so the
task won't run task_works including those that might be important for
the cancellation passes. In this case it's io_poll_remove_one(), which
frees requests via io_put_req_deferred().
Unpark it for while waiting, it's ok as we disable submissions
beforehand, so no new will be generated.
INFO: task syz-executor893:8493 blocked for more than 143 seconds.
Call Trace:
context_switch kernel/sched/core.c:4327 [inline]
__schedule+0x90c/0x21a0 kernel/sched/core.c:5078
schedule+0xcf/0x270 kernel/sched/core.c:5157
io_uring_cancel_files fs/io_uring.c:8912 [inline]
io_uring_cancel_task_requests+0xe70/0x11a0 fs/io_uring.c:8979
__io_uring_files_cancel+0x110/0x1b0 fs/io_uring.c:9067
io_uring_files_cancel include/linux/io_uring.h:51 [inline]
do_exit+0x2fe/0x2ae0 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+0x44/0xa9
Cc: [email protected] # 5.5+
Reported-by: [email protected]
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6b73e38aa1a9..1e803a9afc8e 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9056,11 +9056,16 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
break;
io_uring_try_cancel_requests(ctx, task, files);
+
+ if (ctx->sq_data)
+ io_sq_thread_unpark(ctx->sq_data);
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);
+ if (ctx->sq_data)
+ io_sq_thread_park(ctx->sq_data);
}
}
--
2.24.0
^ permalink raw reply related [flat|nested] 4+ messages in thread