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* [RFC PATCH] io_uring: stop issue failed request to fix panic
@ 2021-09-01  9:39 王贇
  2021-09-01  9:47 ` Pavel Begunkov
  0 siblings, 1 reply; 4+ messages in thread
From: 王贇 @ 2021-09-01  9:39 UTC (permalink / raw)
  To: Jens Axboe, Pavel Begunkov, open list:IO_URING, open list

We observed panic:
  BUG: kernel NULL pointer dereference, address:0000000000000028
  [skip]
  Oops: 0000 [#1] SMP PTI
  CPU: 1 PID: 737 Comm: a.out Not tainted 5.14.0+ #58
  Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
  RIP: 0010:vfs_fadvise+0x1e/0x80
  [skip]
  Call Trace:
   ? tctx_task_work+0x111/0x2a0
   io_issue_sqe+0x524/0x1b90

This is caused by io_wq_submit_work() calling io_issue_sqe()
on a failed fadvise request, and the io_init_req() return error
before initialize the file for it, lead into the panic when
vfs_fadvise() try to access 'req->file'.

This patch add the missing check & handle for failed request
before calling io_issue_sqe().

Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
---
 fs/io_uring.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6f35b12..bfec7bf 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2214,7 +2214,8 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked)

 	io_tw_lock(ctx, locked);
 	/* req->task == current here, checking PF_EXITING is safe */
-	if (likely(!(req->task->flags & PF_EXITING)))
+	if (likely(!(req->task->flags & PF_EXITING) &&
+		   !(req->flags & REQ_F_FAIL)))
 		__io_queue_sqe(req);
 	else
 		io_req_complete_failed(req, -EFAULT);
@@ -6704,7 +6705,10 @@ static void io_wq_submit_work(struct io_wq_work *work)

 	if (!ret) {
 		do {
-			ret = io_issue_sqe(req, 0);
+			if (likely(!(req->flags & REQ_F_FAIL)))
+				ret = io_issue_sqe(req, 0);
+			else
+				io_req_complete_failed(req, -EFAULT);
 			/*
 			 * We can get EAGAIN for polled IO even though we're
 			 * forcing a sync submission from here, since we can't
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [RFC PATCH] io_uring: stop issue failed request to fix panic
  2021-09-01  9:39 [RFC PATCH] io_uring: stop issue failed request to fix panic 王贇
@ 2021-09-01  9:47 ` Pavel Begunkov
  2021-09-01  9:52   ` 王贇
  0 siblings, 1 reply; 4+ messages in thread
From: Pavel Begunkov @ 2021-09-01  9:47 UTC (permalink / raw)
  To: 王贇, Jens Axboe, open list:IO_URING, open list

On 9/1/21 10:39 AM, 王贇 wrote:
> We observed panic:
>   BUG: kernel NULL pointer dereference, address:0000000000000028
>   [skip]
>   Oops: 0000 [#1] SMP PTI
>   CPU: 1 PID: 737 Comm: a.out Not tainted 5.14.0+ #58
>   Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>   RIP: 0010:vfs_fadvise+0x1e/0x80
>   [skip]
>   Call Trace:
>    ? tctx_task_work+0x111/0x2a0
>    io_issue_sqe+0x524/0x1b90

Most likely it was fixed yesterday. Can you try?
https://git.kernel.dk/cgit/linux-block/log/?h=for-5.15/io_uring

Or these two patches in particular

https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=c6d3d9cbd659de8f2176b4e4721149c88ac096d4
https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=b8ce1b9d25ccf81e1bbabd45b963ed98b2222df8

> This is caused by io_wq_submit_work() calling io_issue_sqe()
> on a failed fadvise request, and the io_init_req() return error
> before initialize the file for it, lead into the panic when
> vfs_fadvise() try to access 'req->file'.
> 
> This patch add the missing check & handle for failed request
> before calling io_issue_sqe().
> 
> Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
> ---
>  fs/io_uring.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 6f35b12..bfec7bf 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2214,7 +2214,8 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked)
> 
>  	io_tw_lock(ctx, locked);
>  	/* req->task == current here, checking PF_EXITING is safe */
> -	if (likely(!(req->task->flags & PF_EXITING)))
> +	if (likely(!(req->task->flags & PF_EXITING) &&
> +		   !(req->flags & REQ_F_FAIL)))
>  		__io_queue_sqe(req);
>  	else
>  		io_req_complete_failed(req, -EFAULT);
> @@ -6704,7 +6705,10 @@ static void io_wq_submit_work(struct io_wq_work *work)
> 
>  	if (!ret) {
>  		do {
> -			ret = io_issue_sqe(req, 0);
> +			if (likely(!(req->flags & REQ_F_FAIL)))
> +				ret = io_issue_sqe(req, 0);
> +			else
> +				io_req_complete_failed(req, -EFAULT);
>  			/*
>  			 * We can get EAGAIN for polled IO even though we're
>  			 * forcing a sync submission from here, since we can't
> 

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [RFC PATCH] io_uring: stop issue failed request to fix panic
  2021-09-01  9:47 ` Pavel Begunkov
@ 2021-09-01  9:52   ` 王贇
  2021-09-01 10:59     ` Pavel Begunkov
  0 siblings, 1 reply; 4+ messages in thread
From: 王贇 @ 2021-09-01  9:52 UTC (permalink / raw)
  To: Pavel Begunkov, Jens Axboe, open list:IO_URING, open list



On 2021/9/1 下午5:47, Pavel Begunkov wrote:
> On 9/1/21 10:39 AM, 王贇 wrote:
>> We observed panic:
>>   BUG: kernel NULL pointer dereference, address:0000000000000028
>>   [skip]
>>   Oops: 0000 [#1] SMP PTI
>>   CPU: 1 PID: 737 Comm: a.out Not tainted 5.14.0+ #58
>>   Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>>   RIP: 0010:vfs_fadvise+0x1e/0x80
>>   [skip]
>>   Call Trace:
>>    ? tctx_task_work+0x111/0x2a0
>>    io_issue_sqe+0x524/0x1b90
> 
> Most likely it was fixed yesterday. Can you try?
> https://git.kernel.dk/cgit/linux-block/log/?h=for-5.15/io_uring
> 
> Or these two patches in particular
> 
> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=c6d3d9cbd659de8f2176b4e4721149c88ac096d4
> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=b8ce1b9d25ccf81e1bbabd45b963ed98b2222df8

Yup, it no longer panic :-)

Regards,
Michael Wang

> 
>> This is caused by io_wq_submit_work() calling io_issue_sqe()
>> on a failed fadvise request, and the io_init_req() return error
>> before initialize the file for it, lead into the panic when
>> vfs_fadvise() try to access 'req->file'.
>>
>> This patch add the missing check & handle for failed request
>> before calling io_issue_sqe().
>>
>> Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
>> ---
>>  fs/io_uring.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 6f35b12..bfec7bf 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2214,7 +2214,8 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked)
>>
>>  	io_tw_lock(ctx, locked);
>>  	/* req->task == current here, checking PF_EXITING is safe */
>> -	if (likely(!(req->task->flags & PF_EXITING)))
>> +	if (likely(!(req->task->flags & PF_EXITING) &&
>> +		   !(req->flags & REQ_F_FAIL)))
>>  		__io_queue_sqe(req);
>>  	else
>>  		io_req_complete_failed(req, -EFAULT);
>> @@ -6704,7 +6705,10 @@ static void io_wq_submit_work(struct io_wq_work *work)
>>
>>  	if (!ret) {
>>  		do {
>> -			ret = io_issue_sqe(req, 0);
>> +			if (likely(!(req->flags & REQ_F_FAIL)))
>> +				ret = io_issue_sqe(req, 0);
>> +			else
>> +				io_req_complete_failed(req, -EFAULT);
>>  			/*
>>  			 * We can get EAGAIN for polled IO even though we're
>>  			 * forcing a sync submission from here, since we can't
>>
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [RFC PATCH] io_uring: stop issue failed request to fix panic
  2021-09-01  9:52   ` 王贇
@ 2021-09-01 10:59     ` Pavel Begunkov
  0 siblings, 0 replies; 4+ messages in thread
From: Pavel Begunkov @ 2021-09-01 10:59 UTC (permalink / raw)
  To: 王贇, Jens Axboe, open list:IO_URING, open list

On 9/1/21 10:52 AM, 王贇 wrote:
]> On 2021/9/1 下午5:47, Pavel Begunkov wrote:
>> On 9/1/21 10:39 AM, 王贇 wrote:
>>> We observed panic:
>>>   BUG: kernel NULL pointer dereference, address:0000000000000028
>>>   [skip]
>>>   Oops: 0000 [#1] SMP PTI
>>>   CPU: 1 PID: 737 Comm: a.out Not tainted 5.14.0+ #58
>>>   Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>>>   RIP: 0010:vfs_fadvise+0x1e/0x80
>>>   [skip]
>>>   Call Trace:
>>>    ? tctx_task_work+0x111/0x2a0
>>>    io_issue_sqe+0x524/0x1b90
>>
>> Most likely it was fixed yesterday. Can you try?
>> https://git.kernel.dk/cgit/linux-block/log/?h=for-5.15/io_uring
>>
>> Or these two patches in particular
>>
>> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=c6d3d9cbd659de8f2176b4e4721149c88ac096d4
>> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=b8ce1b9d25ccf81e1bbabd45b963ed98b2222df8
> 
> Yup, it no longer panic :-)

awesome, thanks

> 
> Regards,
> Michael Wang
> 
>>
>>> This is caused by io_wq_submit_work() calling io_issue_sqe()
>>> on a failed fadvise request, and the io_init_req() return error
>>> before initialize the file for it, lead into the panic when
>>> vfs_fadvise() try to access 'req->file'.
>>>
>>> This patch add the missing check & handle for failed request
>>> before calling io_issue_sqe().
>>>
>>> Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
>>> ---
>>>  fs/io_uring.c | 8 ++++++--
>>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index 6f35b12..bfec7bf 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -2214,7 +2214,8 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked)
>>>
>>>  	io_tw_lock(ctx, locked);
>>>  	/* req->task == current here, checking PF_EXITING is safe */
>>> -	if (likely(!(req->task->flags & PF_EXITING)))
>>> +	if (likely(!(req->task->flags & PF_EXITING) &&
>>> +		   !(req->flags & REQ_F_FAIL)))
>>>  		__io_queue_sqe(req);
>>>  	else
>>>  		io_req_complete_failed(req, -EFAULT);
>>> @@ -6704,7 +6705,10 @@ static void io_wq_submit_work(struct io_wq_work *work)
>>>
>>>  	if (!ret) {
>>>  		do {
>>> -			ret = io_issue_sqe(req, 0);
>>> +			if (likely(!(req->flags & REQ_F_FAIL)))
>>> +				ret = io_issue_sqe(req, 0);
>>> +			else
>>> +				io_req_complete_failed(req, -EFAULT);
>>>  			/*
>>>  			 * We can get EAGAIN for polled IO even though we're
>>>  			 * forcing a sync submission from here, since we can't
>>>
>>

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-09-01 11:00 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-09-01  9:39 [RFC PATCH] io_uring: stop issue failed request to fix panic 王贇
2021-09-01  9:47 ` Pavel Begunkov
2021-09-01  9:52   ` 王贇
2021-09-01 10:59     ` Pavel Begunkov

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