4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Hans de Goede]

Hi All,

With 4.8-rc1 I'm seeing WARN_ON(!host->claimed) triggering in both
mmc_start_request() as well as in mmc_release_host(). The first
indicating that we're executing mmc commands without doing
mmc_claim_host() and the second one indicating that we're
releasing the host without having claimed it first.

The backtraces all point to mmc_blk_issue_rq(). I've done
a very naive hack / workaround:

--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -2151,9 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
  	struct mmc_host *host = card->host;
  	unsigned long flags;

-	if (req && !mq->mqrq_prev->req)
-		/* claim host only for the first request */
-		mmc_get_card(card);
+	mmc_get_card(card);

  	ret = mmc_blk_part_switch(card, md);
  	if (ret) {
@@ -2190,15 +2188,8 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
  	}

  out:
-	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
-	    mmc_req_is_special(req))
-		/*
-		 * Release host when there are no more requests
-		 * and after special request(discard, flush) is done.
-		 * In case sepecial request, there is no reentry to
-		 * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
-		 */
-		mmc_put_card(card);
+	mmc_put_card(card);
+
  	return ret;
  }


Which fixes this, further pointing to the somewhat magical claim / release
code in mmc_blk_issue_rq() being the culprit.

Looking at recent commits these 2 stand out as possible causes of this:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c2df40dfb8c015211ec55f4b1dd0587f875c7b34
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a5e02ced11e22ecd9da3d6710afe15bcfee1d10

I've the feeling that one of these is making mmc_blk_issue_rq() not claiming
the host while it should do so ...

Maybe instead of the magic at the top we need a simple bool to check
if the host is already claimed by the mmc_queue code ?

I can reproduce the WARN_ON's pretty much at will (running 4.8-rc1 on
Allwinner ARM devices with rootfs on a sdcard), let me know if you've
a fix you want me to test.

Regards,

Hans


p.s.

Besides the WARN_ON triggering another side-effect of this is that the
machines will hang at poweroff.

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Mike Christie]

On 08/21/2016 10:15 AM, Hans de Goede wrote:
> Hi All,
> 
> With 4.8-rc1 I'm seeing WARN_ON(!host->claimed) triggering in both
> mmc_start_request() as well as in mmc_release_host(). The first
> indicating that we're executing mmc commands without doing
> mmc_claim_host() and the second one indicating that we're
> releasing the host without having claimed it first.
> 
> The backtraces all point to mmc_blk_issue_rq(). I've done
> a very naive hack / workaround:
> 
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -2151,9 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
> struct request *req)
>      struct mmc_host *host = card->host;
>      unsigned long flags;
> 
> -    if (req && !mq->mqrq_prev->req)
> -        /* claim host only for the first request */
> -        mmc_get_card(card);
> +    mmc_get_card(card);
> 
>      ret = mmc_blk_part_switch(card, md);
>      if (ret) {
> @@ -2190,15 +2188,8 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
> struct request *req)
>      }
> 
>  out:
> -    if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
> -        mmc_req_is_special(req))
> -        /*
> -         * Release host when there are no more requests
> -         * and after special request(discard, flush) is done.
> -         * In case sepecial request, there is no reentry to
> -         * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
> -         */
> -        mmc_put_card(card);
> +    mmc_put_card(card);
> +
>      return ret;
>  }
> 
> 
> Which fixes this, further pointing to the somewhat magical claim / release
> code in mmc_blk_issue_rq() being the culprit.
> 
> Looking at recent commits these 2 stand out as possible causes of this:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c2df40dfb8c015211ec55f4b1dd0587f875c7b34
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a5e02ced11e22ecd9da3d6710afe15bcfee1d10
> 
> 
> I've the feeling that one of these is making mmc_blk_issue_rq() not
> claiming
> the host while it should do so ...
> 

There is a bug with those patches and the secure discard ones where when
REQ_OP_SECURE_ERASE is sent, mmc_put_card above will not be called, and
they will be treated as normal requests instead of special one so the
drivers lists are not executed properly.

The patch in Jens's tree
https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=7afafc8a44bf0ab841b17d450b02aedb3a138985
fixes the issue.

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Hans de Goede]

Hi,

On 22-08-16 18:09, Mike Christie wrote:
> On 08/21/2016 10:15 AM, Hans de Goede wrote:
>> Hi All,
>>
>> With 4.8-rc1 I'm seeing WARN_ON(!host->claimed) triggering in both
>> mmc_start_request() as well as in mmc_release_host(). The first
>> indicating that we're executing mmc commands without doing
>> mmc_claim_host() and the second one indicating that we're
>> releasing the host without having claimed it first.
>>
>> The backtraces all point to mmc_blk_issue_rq(). I've done
>> a very naive hack / workaround:
>>
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -2151,9 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>> struct request *req)
>>      struct mmc_host *host = card->host;
>>      unsigned long flags;
>>
>> -    if (req && !mq->mqrq_prev->req)
>> -        /* claim host only for the first request */
>> -        mmc_get_card(card);
>> +    mmc_get_card(card);
>>
>>      ret = mmc_blk_part_switch(card, md);
>>      if (ret) {
>> @@ -2190,15 +2188,8 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>> struct request *req)
>>      }
>>
>>  out:
>> -    if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
>> -        mmc_req_is_special(req))
>> -        /*
>> -         * Release host when there are no more requests
>> -         * and after special request(discard, flush) is done.
>> -         * In case sepecial request, there is no reentry to
>> -         * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
>> -         */
>> -        mmc_put_card(card);
>> +    mmc_put_card(card);
>> +
>>      return ret;
>>  }
>>
>>
>> Which fixes this, further pointing to the somewhat magical claim / release
>> code in mmc_blk_issue_rq() being the culprit.
>>
>> Looking at recent commits these 2 stand out as possible causes of this:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c2df40dfb8c015211ec55f4b1dd0587f875c7b34
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a5e02ced11e22ecd9da3d6710afe15bcfee1d10
>>
>>
>> I've the feeling that one of these is making mmc_blk_issue_rq() not
>> claiming
>> the host while it should do so ...
>>
>
> There is a bug with those patches and the secure discard ones where when
> REQ_OP_SECURE_ERASE is sent, mmc_put_card above will not be called, and
> they will be treated as normal requests instead of special one so the
> drivers lists are not executed properly.

Actually the problem seems to be mmc_get_card not getting called while it
should at the top of mmc_blk_issue_rq, I first get a WARN_ON(!host->claimed)
triggering in mmc_start_request (so missing mmc_card_get) and then
in mmc_release_host (mmc_card_put called without mc_card_get being called
first).

> The patch in Jens's tree
> https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=7afafc8a44bf0ab841b17d450b02aedb3a138985
> fixes the issue.

I've tried 4.8-rc3 with my hack drop and this commit cherry-picked,
but the problem is still there, so this patch does not fix it.

Regards,

Hans

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Adrian Hunter]

On 24/08/16 11:47, Hans de Goede wrote:
> Hi,
> 
> On 22-08-16 18:09, Mike Christie wrote:
>> On 08/21/2016 10:15 AM, Hans de Goede wrote:
>>> Hi All,
>>>
>>> With 4.8-rc1 I'm seeing WARN_ON(!host->claimed) triggering in both
>>> mmc_start_request() as well as in mmc_release_host(). The first
>>> indicating that we're executing mmc commands without doing
>>> mmc_claim_host() and the second one indicating that we're
>>> releasing the host without having claimed it first.
>>>
>>> The backtraces all point to mmc_blk_issue_rq(). I've done
>>> a very naive hack / workaround:
>>>
>>> --- a/drivers/mmc/card/block.c
>>> +++ b/drivers/mmc/card/block.c
>>> @@ -2151,9 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>>> struct request *req)
>>>      struct mmc_host *host = card->host;
>>>      unsigned long flags;
>>>
>>> -    if (req && !mq->mqrq_prev->req)
>>> -        /* claim host only for the first request */
>>> -        mmc_get_card(card);
>>> +    mmc_get_card(card);
>>>
>>>      ret = mmc_blk_part_switch(card, md);
>>>      if (ret) {
>>> @@ -2190,15 +2188,8 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>>> struct request *req)
>>>      }
>>>
>>>  out:
>>> -    if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
>>> -        mmc_req_is_special(req))
>>> -        /*
>>> -         * Release host when there are no more requests
>>> -         * and after special request(discard, flush) is done.
>>> -         * In case sepecial request, there is no reentry to
>>> -         * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
>>> -         */
>>> -        mmc_put_card(card);
>>> +    mmc_put_card(card);
>>> +
>>>      return ret;
>>>  }
>>>
>>>
>>> Which fixes this, further pointing to the somewhat magical claim / release
>>> code in mmc_blk_issue_rq() being the culprit.
>>>
>>> Looking at recent commits these 2 stand out as possible causes of this:
>>>
>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c2df40dfb8c015211ec55f4b1dd0587f875c7b34
>>>
>>>
>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a5e02ced11e22ecd9da3d6710afe15bcfee1d10
>>>
>>>
>>>
>>> I've the feeling that one of these is making mmc_blk_issue_rq() not
>>> claiming
>>> the host while it should do so ...
>>>
>>
>> There is a bug with those patches and the secure discard ones where when
>> REQ_OP_SECURE_ERASE is sent, mmc_put_card above will not be called, and
>> they will be treated as normal requests instead of special one so the
>> drivers lists are not executed properly.
> 
> Actually the problem seems to be mmc_get_card not getting called while it
> should at the top of mmc_blk_issue_rq, I first get a WARN_ON(!host->claimed)
> triggering in mmc_start_request (so missing mmc_card_get) and then
> in mmc_release_host (mmc_card_put called without mc_card_get being called
> first).
> 
>> The patch in Jens's tree
>> https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=7afafc8a44bf0ab841b17d450b02aedb3a138985
>>
>> fixes the issue.
> 
> I've tried 4.8-rc3 with my hack drop and this commit cherry-picked,
> but the problem is still there, so this patch does not fix it.

I wasn't able to reproduce your problem, but a possibility could be
accessing the request after it is completed.  You could try this:

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 82503e6f04b3..2206d4477dbb 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -2151,6 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 	struct mmc_card *card = md->queue.card;
 	struct mmc_host *host = card->host;
 	unsigned long flags;
+	bool req_is_special = mmc_req_is_special(req);
 
 	if (req && !mq->mqrq_prev->req)
 		/* claim host only for the first request */
@@ -2191,8 +2192,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 	}
 
 out:
-	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
-	    mmc_req_is_special(req))
+	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) || req_is_special)
 		/*
 		 * Release host when there are no more requests
 		 * and after special request(discard, flush) is done.
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 29578e98603d..708057261b38 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -65,6 +65,8 @@ static int mmc_queue_thread(void *d)
 		spin_unlock_irq(q->queue_lock);
 
 		if (req || mq->mqrq_prev->req) {
+			bool req_is_special = mmc_req_is_special(req);
+
 			set_current_state(TASK_RUNNING);
 			mq->issue_fn(mq, req);
 			cond_resched();
@@ -80,7 +82,7 @@ static int mmc_queue_thread(void *d)
 			 * has been finished. Do not assign it to previous
 			 * request.
 			 */
-			if (mmc_req_is_special(req))
+			if (req_is_special)
 				mq->mqrq_cur->req = NULL;
 
 			mq->mqrq_prev->brq.mrq.data = NULL;

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Jens Axboe]

On 08/25/2016 02:19 AM, Adrian Hunter wrote:
> On 24/08/16 11:47, Hans de Goede wrote:
>> Hi,
>>
>> On 22-08-16 18:09, Mike Christie wrote:
>>> On 08/21/2016 10:15 AM, Hans de Goede wrote:
>>>> Hi All,
>>>>
>>>> With 4.8-rc1 I'm seeing WARN_ON(!host->claimed) triggering in both
>>>> mmc_start_request() as well as in mmc_release_host(). The first
>>>> indicating that we're executing mmc commands without doing
>>>> mmc_claim_host() and the second one indicating that we're
>>>> releasing the host without having claimed it first.
>>>>
>>>> The backtraces all point to mmc_blk_issue_rq(). I've done
>>>> a very naive hack / workaround:
>>>>
>>>> --- a/drivers/mmc/card/block.c
>>>> +++ b/drivers/mmc/card/block.c
>>>> @@ -2151,9 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>>>> struct request *req)
>>>>      struct mmc_host *host = card->host;
>>>>      unsigned long flags;
>>>>
>>>> -    if (req && !mq->mqrq_prev->req)
>>>> -        /* claim host only for the first request */
>>>> -        mmc_get_card(card);
>>>> +    mmc_get_card(card);
>>>>
>>>>      ret = mmc_blk_part_switch(card, md);
>>>>      if (ret) {
>>>> @@ -2190,15 +2188,8 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>>>> struct request *req)
>>>>      }
>>>>
>>>>  out:
>>>> -    if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
>>>> -        mmc_req_is_special(req))
>>>> -        /*
>>>> -         * Release host when there are no more requests
>>>> -         * and after special request(discard, flush) is done.
>>>> -         * In case sepecial request, there is no reentry to
>>>> -         * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
>>>> -         */
>>>> -        mmc_put_card(card);
>>>> +    mmc_put_card(card);
>>>> +
>>>>      return ret;
>>>>  }
>>>>
>>>>
>>>> Which fixes this, further pointing to the somewhat magical claim / release
>>>> code in mmc_blk_issue_rq() being the culprit.
>>>>
>>>> Looking at recent commits these 2 stand out as possible causes of this:
>>>>
>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c2df40dfb8c015211ec55f4b1dd0587f875c7b34
>>>>
>>>>
>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a5e02ced11e22ecd9da3d6710afe15bcfee1d10
>>>>
>>>>
>>>>
>>>> I've the feeling that one of these is making mmc_blk_issue_rq() not
>>>> claiming
>>>> the host while it should do so ...
>>>>
>>>
>>> There is a bug with those patches and the secure discard ones where when
>>> REQ_OP_SECURE_ERASE is sent, mmc_put_card above will not be called, and
>>> they will be treated as normal requests instead of special one so the
>>> drivers lists are not executed properly.
>>
>> Actually the problem seems to be mmc_get_card not getting called while it
>> should at the top of mmc_blk_issue_rq, I first get a WARN_ON(!host->claimed)
>> triggering in mmc_start_request (so missing mmc_card_get) and then
>> in mmc_release_host (mmc_card_put called without mc_card_get being called
>> first).
>>
>>> The patch in Jens's tree
>>> https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=7afafc8a44bf0ab841b17d450b02aedb3a138985
>>>
>>> fixes the issue.
>>
>> I've tried 4.8-rc3 with my hack drop and this commit cherry-picked,
>> but the problem is still there, so this patch does not fix it.
>
> I wasn't able to reproduce your problem, but a possibility could be
> accessing the request after it is completed.  You could try this:
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 82503e6f04b3..2206d4477dbb 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -2151,6 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>  	struct mmc_card *card = md->queue.card;
>  	struct mmc_host *host = card->host;
>  	unsigned long flags;
> +	bool req_is_special = mmc_req_is_special(req);
>
>  	if (req && !mq->mqrq_prev->req)
>  		/* claim host only for the first request */
> @@ -2191,8 +2192,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>  	}
>
>  out:
> -	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
> -	    mmc_req_is_special(req))
> +	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) || req_is_special)
>  		/*
>  		 * Release host when there are no more requests
>  		 * and after special request(discard, flush) is done.
> diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
> index 29578e98603d..708057261b38 100644
> --- a/drivers/mmc/card/queue.c
> +++ b/drivers/mmc/card/queue.c
> @@ -65,6 +65,8 @@ static int mmc_queue_thread(void *d)
>  		spin_unlock_irq(q->queue_lock);
>
>  		if (req || mq->mqrq_prev->req) {
> +			bool req_is_special = mmc_req_is_special(req);
> +
>  			set_current_state(TASK_RUNNING);
>  			mq->issue_fn(mq, req);
>  			cond_resched();
> @@ -80,7 +82,7 @@ static int mmc_queue_thread(void *d)
>  			 * has been finished. Do not assign it to previous
>  			 * request.
>  			 */
> -			if (mmc_req_is_special(req))
> +			if (req_is_special)
>  				mq->mqrq_cur->req = NULL;
>
>  			mq->mqrq_prev->brq.mrq.data = NULL;

Those definitely look like legitimate bugs, introduced by:

commit c2df40dfb8c015211ec55f4b1dd0587f875c7b34
Author: Mike Christie <mchristi@redhat.com>
Date:   Sun Jun 5 14:32:17 2016 -0500

     drivers: use req op accessor

Adrian, let's get this stuffed into 4.8. Can you resend as a proper
patch?

-- 
Jens Axboe

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Hans de Goede]

Hi,

On 25-08-16 10:19, Adrian Hunter wrote:
> On 24/08/16 11:47, Hans de Goede wrote:
>> Hi,
>>
>> On 22-08-16 18:09, Mike Christie wrote:
>>> On 08/21/2016 10:15 AM, Hans de Goede wrote:
>>>> Hi All,
>>>>
>>>> With 4.8-rc1 I'm seeing WARN_ON(!host->claimed) triggering in both
>>>> mmc_start_request() as well as in mmc_release_host(). The first
>>>> indicating that we're executing mmc commands without doing
>>>> mmc_claim_host() and the second one indicating that we're
>>>> releasing the host without having claimed it first.
>>>>
>>>> The backtraces all point to mmc_blk_issue_rq(). I've done
>>>> a very naive hack / workaround:
>>>>
>>>> --- a/drivers/mmc/card/block.c
>>>> +++ b/drivers/mmc/card/block.c
>>>> @@ -2151,9 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>>>> struct request *req)
>>>>      struct mmc_host *host = card->host;
>>>>      unsigned long flags;
>>>>
>>>> -    if (req && !mq->mqrq_prev->req)
>>>> -        /* claim host only for the first request */
>>>> -        mmc_get_card(card);
>>>> +    mmc_get_card(card);
>>>>
>>>>      ret = mmc_blk_part_switch(card, md);
>>>>      if (ret) {
>>>> @@ -2190,15 +2188,8 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq,
>>>> struct request *req)
>>>>      }
>>>>
>>>>  out:
>>>> -    if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
>>>> -        mmc_req_is_special(req))
>>>> -        /*
>>>> -         * Release host when there are no more requests
>>>> -         * and after special request(discard, flush) is done.
>>>> -         * In case sepecial request, there is no reentry to
>>>> -         * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
>>>> -         */
>>>> -        mmc_put_card(card);
>>>> +    mmc_put_card(card);
>>>> +
>>>>      return ret;
>>>>  }
>>>>
>>>>
>>>> Which fixes this, further pointing to the somewhat magical claim / release
>>>> code in mmc_blk_issue_rq() being the culprit.
>>>>
>>>> Looking at recent commits these 2 stand out as possible causes of this:
>>>>
>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c2df40dfb8c015211ec55f4b1dd0587f875c7b34
>>>>
>>>>
>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a5e02ced11e22ecd9da3d6710afe15bcfee1d10
>>>>
>>>>
>>>>
>>>> I've the feeling that one of these is making mmc_blk_issue_rq() not
>>>> claiming
>>>> the host while it should do so ...
>>>>
>>>
>>> There is a bug with those patches and the secure discard ones where when
>>> REQ_OP_SECURE_ERASE is sent, mmc_put_card above will not be called, and
>>> they will be treated as normal requests instead of special one so the
>>> drivers lists are not executed properly.
>>
>> Actually the problem seems to be mmc_get_card not getting called while it
>> should at the top of mmc_blk_issue_rq, I first get a WARN_ON(!host->claimed)
>> triggering in mmc_start_request (so missing mmc_card_get) and then
>> in mmc_release_host (mmc_card_put called without mc_card_get being called
>> first).
>>
>>> The patch in Jens's tree
>>> https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=7afafc8a44bf0ab841b17d450b02aedb3a138985
>>>
>>> fixes the issue.
>>
>> I've tried 4.8-rc3 with my hack drop and this commit cherry-picked,
>> but the problem is still there, so this patch does not fix it.
>
> I wasn't able to reproduce your problem, but a possibility could be
> accessing the request after it is completed.  You could try this:

Good catch, that seems to fix things for me. Note sometimes this bug
would not hit immediately for me. But I've been running several
affected boards for about 1 hour or so, without issues, so I believe
this is fixed. So this is:

Tested-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans


>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 82503e6f04b3..2206d4477dbb 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -2151,6 +2151,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>  	struct mmc_card *card = md->queue.card;
>  	struct mmc_host *host = card->host;
>  	unsigned long flags;
> +	bool req_is_special = mmc_req_is_special(req);
>
>  	if (req && !mq->mqrq_prev->req)
>  		/* claim host only for the first request */
> @@ -2191,8 +2192,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>  	}
>
>  out:
> -	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
> -	    mmc_req_is_special(req))
> +	if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) || req_is_special)
>  		/*
>  		 * Release host when there are no more requests
>  		 * and after special request(discard, flush) is done.
> diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
> index 29578e98603d..708057261b38 100644
> --- a/drivers/mmc/card/queue.c
> +++ b/drivers/mmc/card/queue.c
> @@ -65,6 +65,8 @@ static int mmc_queue_thread(void *d)
>  		spin_unlock_irq(q->queue_lock);
>
>  		if (req || mq->mqrq_prev->req) {
> +			bool req_is_special = mmc_req_is_special(req);
> +
>  			set_current_state(TASK_RUNNING);
>  			mq->issue_fn(mq, req);
>  			cond_resched();
> @@ -80,7 +82,7 @@ static int mmc_queue_thread(void *d)
>  			 * has been finished. Do not assign it to previous
>  			 * request.
>  			 */
> -			if (mmc_req_is_special(req))
> +			if (req_is_special)
>  				mq->mqrq_cur->req = NULL;
>
>  			mq->mqrq_prev->brq.mrq.data = NULL;
>
>

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Jens Axboe]

On 08/25/2016 12:26 PM, Hans de Goede wrote:
>>> I've tried 4.8-rc3 with my hack drop and this commit cherry-picked,
>>> but the problem is still there, so this patch does not fix it.
>>
>> I wasn't able to reproduce your problem, but a possibility could be
>> accessing the request after it is completed.  You could try this:
>
> Good catch, that seems to fix things for me. Note sometimes this bug
> would not hit immediately for me. But I've been running several
> affected boards for about 1 hour or so, without issues, so I believe
> this is fixed. So this is:
>
> Tested-by: Hans de Goede <hdegoede@redhat.com>

Awesome, thanks for reporting/testing. Adrian, I have turned it into a 
real patch and applied it for 4.8. Thanks!


-- 
Jens Axboe

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Ulf Hansson]

On 25 August 2016 at 22:12, Jens Axboe <axboe@fb.com> wrote:
> On 08/25/2016 12:26 PM, Hans de Goede wrote:
>>>>
>>>> I've tried 4.8-rc3 with my hack drop and this commit cherry-picked,
>>>> but the problem is still there, so this patch does not fix it.
>>>
>>>
>>> I wasn't able to reproduce your problem, but a possibility could be
>>> accessing the request after it is completed.  You could try this:
>>
>>
>> Good catch, that seems to fix things for me. Note sometimes this bug
>> would not hit immediately for me. But I've been running several
>> affected boards for about 1 hour or so, without issues, so I believe
>> this is fixed. So this is:
>>
>> Tested-by: Hans de Goede <hdegoede@redhat.com>
>
>
> Awesome, thanks for reporting/testing. Adrian, I have turned it into a real
> patch and applied it for 4.8. Thanks!

Jens, thanks for helping out! You may add my ack for it!

Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

BTW, for some reason I (and linux-mmc) was not cc:ed on the commit
that caused the regression:

c2df40dfb8c015211ec55f4b1dd0587f875c7b34
Author: Mike Christie <mchristi@redhat.com>
Date:   Sun Jun 5 14:32:17 2016 -0500
    drivers: use req op accessor

Even if I probably wouldn't noticed that the patch was incorrect, it
would have helped to know that we changed some parts in the mmc block
layer when trying to find the regression. Could you please keep on eye
on this future wise so it doesn't happen again.

Kind regards
Uffe

Re: 4.8-rc1 REGRESSION mmc-blk triggers WARN_ON(!host->claimed), related to: "drivers: use req op accessor" ?

[Mike Christie]

On 08/26/2016 02:13 AM, Ulf Hansson wrote:
> BTW, for some reason I (and linux-mmc) was not cc:ed on the commit
> that caused the regression:
> 
> c2df40dfb8c015211ec55f4b1dd0587f875c7b34
> Author: Mike Christie <mchristi@redhat.com>
> Date:   Sun Jun 5 14:32:17 2016 -0500
>     drivers: use req op accessor
> 
> Even if I probably wouldn't noticed that the patch was incorrect, it
> would have helped to know that we changed some parts in the mmc block
> layer when trying to find the regression. Could you please keep on eye
> on this future wise so it doesn't happen again.

Sorry about that and the bug. Both were my fault. Will be more careful
in the future.