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@xxxxxxxxxx>
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
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