From: Jianchao Wang jianchao.w.wang@oracle.com
commit f5bbbbe4d63577026f908a809f22f5fd5a90ea1f upstream.
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to account the inflight requests. It will access the queue_hw_ctx and nr_hw_queues w/o any protection. When updating nr_hw_queues and blk_mq_in_flight/rw occur concurrently, panic comes up.
Before update nr_hw_queues, the q will be frozen. So we could use q_usage_counter to avoid the race. percpu_ref_is_zero is used here so that we will not miss any in-flight request. The access to nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are under rcu critical section, __blk_mq_update_nr_hw_queues could use synchronize_rcu to ensure the zeroed q_usage_counter to be globally visible.
Backporting Notes
This is a re-backport, landing synchronize_rcu in the right place.
Signed-off-by: Jianchao Wang jianchao.w.wang@oracle.com Reviewed-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Giuliano Procida gprocida@google.com --- block/blk-mq.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 9d53f476c517..cf56bdad2e06 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2738,6 +2738,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_freeze_queue(q); + /* + * Sync with blk_mq_queue_tag_busy_iter. + */ + synchronize_rcu();
set->nr_hw_queues = nr_hw_queues; blk_mq_update_queue_map(set); @@ -2748,10 +2752,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_unfreeze_queue(q); - /* - * Sync with blk_mq_queue_tag_busy_iter. - */ - synchronize_rcu(); }
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
-bouncing mail.
This one is for 4.14. Apologies.
Giuliano.
On Mon, 8 Jun 2020 at 10:39, Giuliano Procida gprocida@google.com wrote:
From: Jianchao Wang jianchao.w.wang@oracle.com
commit f5bbbbe4d63577026f908a809f22f5fd5a90ea1f upstream.
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to account the inflight requests. It will access the queue_hw_ctx and nr_hw_queues w/o any protection. When updating nr_hw_queues and blk_mq_in_flight/rw occur concurrently, panic comes up.
Before update nr_hw_queues, the q will be frozen. So we could use q_usage_counter to avoid the race. percpu_ref_is_zero is used here so that we will not miss any in-flight request. The access to nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are under rcu critical section, __blk_mq_update_nr_hw_queues could use synchronize_rcu to ensure the zeroed q_usage_counter to be globally visible.
Backporting Notes
This is a re-backport, landing synchronize_rcu in the right place.
Signed-off-by: Jianchao Wang jianchao.w.wang@oracle.com Reviewed-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Giuliano Procida gprocida@google.com
block/blk-mq.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 9d53f476c517..cf56bdad2e06 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2738,6 +2738,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_freeze_queue(q);
/** Sync with blk_mq_queue_tag_busy_iter.*/synchronize_rcu(); set->nr_hw_queues = nr_hw_queues; blk_mq_update_queue_map(set);@@ -2748,10 +2752,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_unfreeze_queue(q);
/** Sync with blk_mq_queue_tag_busy_iter.*/synchronize_rcu();}
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2.27.0.278.ge193c7cf3a9-goog
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
Giuliano.
On Mon, 8 Jun 2020 at 14:01, Giuliano Procida gprocida@google.com wrote:
-bouncing mail.
This one is for 4.14. Apologies.
Giuliano.
On Mon, 8 Jun 2020 at 10:39, Giuliano Procida gprocida@google.com wrote:
From: Jianchao Wang jianchao.w.wang@oracle.com
commit f5bbbbe4d63577026f908a809f22f5fd5a90ea1f upstream.
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to account the inflight requests. It will access the queue_hw_ctx and nr_hw_queues w/o any protection. When updating nr_hw_queues and blk_mq_in_flight/rw occur concurrently, panic comes up.
Before update nr_hw_queues, the q will be frozen. So we could use q_usage_counter to avoid the race. percpu_ref_is_zero is used here so that we will not miss any in-flight request. The access to nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are under rcu critical section, __blk_mq_update_nr_hw_queues could use synchronize_rcu to ensure the zeroed q_usage_counter to be globally visible.
Backporting Notes
This is a re-backport, landing synchronize_rcu in the right place.
Signed-off-by: Jianchao Wang jianchao.w.wang@oracle.com Reviewed-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Giuliano Procida gprocida@google.com
block/blk-mq.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 9d53f476c517..cf56bdad2e06 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2738,6 +2738,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_freeze_queue(q);
/** Sync with blk_mq_queue_tag_busy_iter.*/synchronize_rcu(); set->nr_hw_queues = nr_hw_queues; blk_mq_update_queue_map(set);@@ -2748,10 +2752,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_unfreeze_queue(q);
/** Sync with blk_mq_queue_tag_busy_iter.*/synchronize_rcu();}
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2.27.0.278.ge193c7cf3a9-goog
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote:
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
Or is there some other upstream commit you are referring to here?
thanks,
greg k-h
Hi.
On Thu, 18 Jun 2020 at 08:33, Greg KH greg@kroah.com wrote:
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
I'm well aware of the above. Alas, I haven't used mutt properly in about 15 years and I'm still doing everything with Gmail. Given that I was referring to the entire email thread, I punted on finding a place to insert a comment. BTW, there's a typo in the Q&A above. s/Were/Where/ :)
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote:
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
We are referring to different "it"s.
Yours: f5bbbbe4d635 is the upstream patch that went into v4.19-rc1 and which you back-ported to at least some of these kernels. This is clearly there.
Mine: the commit sent earlier in this email thread - it's a re-back-port, as I think the original back-port for 4.14 (and similarly for 4.9) is incorrect. This has clearly not reached public git, hence my question about whether the change was queued.
These are the ids of messages containing my commits:
4.14: 20200608093950.86293-1-gprocida@google.com 4.9: 20200608094030.87031-1-gprocida@google.com
Or is there some other upstream commit you are referring to here?
No.
thanks,
greg k-h
I hope this clears things up.
Regards, Giuliano.
On Thu, Jun 18, 2020 at 10:16:45AM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 08:33, Greg KH greg@kroah.com wrote:
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
I'm well aware of the above. Alas, I haven't used mutt properly in about 15 years and I'm still doing everything with Gmail.
gmail can handle proper quoting, if you are stuck with that :)
Given that I was referring to the entire email thread, I punted on finding a place to insert a comment. BTW, there's a typo in the Q&A above. s/Were/Where/
Ah, nice catch, first one to notice that in years!
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote:
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
We are referring to different "it"s.
Yours: f5bbbbe4d635 is the upstream patch that went into v4.19-rc1 and which you back-ported to at least some of these kernels. This is clearly there.
Great.
Mine: the commit sent earlier in this email thread - it's a re-back-port, as I think the original back-port for 4.14 (and similarly for 4.9) is incorrect. This has clearly not reached public git, hence my question about whether the change was queued.
I don't know what the git commit id you are looking for here, sorry. I don't have the whole thread anywhere.
These are the ids of messages containing my commits:
4.14: 20200608093950.86293-1-gprocida@google.com 4.9: 20200608094030.87031-1-gprocida@google.com
Pointers to this on lore.kernel.org perhaps?
Remember, some of us get thousands of patches a week to handle, remembering old email thread, or even keeping them around, is impossible...
thanks,
greg k-h
Hi.
On Thu, 18 Jun 2020 at 15:59, Greg KH greg@kroah.com wrote:
On Thu, Jun 18, 2020 at 10:16:45AM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 08:33, Greg KH greg@kroah.com wrote:
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
I'm well aware of the above. Alas, I haven't used mutt properly in about 15 years and I'm still doing everything with Gmail.
gmail can handle proper quoting, if you are stuck with that :)
Given that I was referring to the entire email thread, I punted on finding a place to insert a comment. BTW, there's a typo in the Q&A above. s/Were/Where/
Ah, nice catch, first one to notice that in years!
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote:
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
We are referring to different "it"s.
Yours: f5bbbbe4d635 is the upstream patch that went into v4.19-rc1 and which you back-ported to at least some of these kernels. This is clearly there.
Great.
Mine: the commit sent earlier in this email thread - it's a re-back-port, as I think the original back-port for 4.14 (and similarly for 4.9) is incorrect. This has clearly not reached public git, hence my question about whether the change was queued.
I don't know what the git commit id you are looking for here, sorry. I don't have the whole thread anywhere.
These are the ids of messages containing my commits:
4.14: 20200608093950.86293-1-gprocida@google.com 4.9: 20200608094030.87031-1-gprocida@google.com
Pointers to this on lore.kernel.org perhaps?
I wasn't aware stable was publicly archived. Here you go:
4.14: https://lore.kernel.org/stable/20200608093950.86293-1-gprocida@google.com/ 4.9: https://lore.kernel.org/stable/20200608094030.87031-1-gprocida@google.com/
Regards, Giuliano.
thanks
Remember, some of us get thousands of patches a week to handle, remembering old email thread, or even keeping them around, is impossible...
greg k-h
On Thu, Jun 18, 2020 at 04:35:03PM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 15:59, Greg KH greg@kroah.com wrote:
On Thu, Jun 18, 2020 at 10:16:45AM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 08:33, Greg KH greg@kroah.com wrote:
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
I'm well aware of the above. Alas, I haven't used mutt properly in about 15 years and I'm still doing everything with Gmail.
gmail can handle proper quoting, if you are stuck with that :)
Given that I was referring to the entire email thread, I punted on finding a place to insert a comment. BTW, there's a typo in the Q&A above. s/Were/Where/
Ah, nice catch, first one to notice that in years!
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote:
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
We are referring to different "it"s.
Yours: f5bbbbe4d635 is the upstream patch that went into v4.19-rc1 and which you back-ported to at least some of these kernels. This is clearly there.
Great.
Mine: the commit sent earlier in this email thread - it's a re-back-port, as I think the original back-port for 4.14 (and similarly for 4.9) is incorrect. This has clearly not reached public git, hence my question about whether the change was queued.
I don't know what the git commit id you are looking for here, sorry. I don't have the whole thread anywhere.
These are the ids of messages containing my commits:
4.14: 20200608093950.86293-1-gprocida@google.com 4.9: 20200608094030.87031-1-gprocida@google.com
Pointers to this on lore.kernel.org perhaps?
I wasn't aware stable was publicly archived. Here you go:
4.14: https://lore.kernel.org/stable/20200608093950.86293-1-gprocida@google.com/ 4.9: https://lore.kernel.org/stable/20200608094030.87031-1-gprocida@google.com/
As per the git commit id in those emails, you should be able to determine the same thing that I can, namely that that patch is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
thanks,
greg k-h
Hi.
On Thu, 18 Jun 2020 at 17:05, Greg KH greg@kroah.com wrote:
On Thu, Jun 18, 2020 at 04:35:03PM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 15:59, Greg KH greg@kroah.com wrote:
On Thu, Jun 18, 2020 at 10:16:45AM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 08:33, Greg KH greg@kroah.com wrote:
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
I'm well aware of the above. Alas, I haven't used mutt properly in about 15 years and I'm still doing everything with Gmail.
gmail can handle proper quoting, if you are stuck with that :)
Given that I was referring to the entire email thread, I punted on finding a place to insert a comment. BTW, there's a typo in the Q&A above. s/Were/Where/
Ah, nice catch, first one to notice that in years!
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote:
Hi Greg.
Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
We are referring to different "it"s.
Yours: f5bbbbe4d635 is the upstream patch that went into v4.19-rc1 and which you back-ported to at least some of these kernels. This is clearly there.
Great.
Mine: the commit sent earlier in this email thread - it's a re-back-port, as I think the original back-port for 4.14 (and similarly for 4.9) is incorrect. This has clearly not reached public git, hence my question about whether the change was queued.
I don't know what the git commit id you are looking for here, sorry. I don't have the whole thread anywhere.
These are the ids of messages containing my commits:
4.14: 20200608093950.86293-1-gprocida@google.com 4.9: 20200608094030.87031-1-gprocida@google.com
Pointers to this on lore.kernel.org perhaps?
I wasn't aware stable was publicly archived. Here you go:
4.14: https://lore.kernel.org/stable/20200608093950.86293-1-gprocida@google.com/ 4.9: https://lore.kernel.org/stable/20200608094030.87031-1-gprocida@google.com/
As per the git commit id in those emails, you should be able to determine the same thing that I can, namely that that patch is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Both those commits contain the text:
"Backporting Notes
This is a re-backport, landing synchronize_rcu in the right place."
If there's a special procedure for fixing back-ports, let me know, 'cos I haven't found one!
Cheers, Giuliano.
thanks,
greg k-h
On Thu, Jun 18, 2020 at 05:14:23PM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 17:05, Greg KH greg@kroah.com wrote:
On Thu, Jun 18, 2020 at 04:35:03PM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 15:59, Greg KH greg@kroah.com wrote:
On Thu, Jun 18, 2020 at 10:16:45AM +0100, Giuliano Procida wrote:
Hi.
On Thu, 18 Jun 2020 at 08:33, Greg KH greg@kroah.com wrote:
A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
A: No. Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
:)
I'm well aware of the above. Alas, I haven't used mutt properly in about 15 years and I'm still doing everything with Gmail.
gmail can handle proper quoting, if you are stuck with that :)
Given that I was referring to the entire email thread, I punted on finding a place to insert a comment. BTW, there's a typo in the Q&A above. s/Were/Where/
Ah, nice catch, first one to notice that in years!
On Thu, Jun 18, 2020 at 08:27:55AM +0100, Giuliano Procida wrote: > Hi Greg. > > Is this patch (and the similar one for 4.9) queued?
f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Do you not see it there?
We are referring to different "it"s.
Yours: f5bbbbe4d635 is the upstream patch that went into v4.19-rc1 and which you back-ported to at least some of these kernels. This is clearly there.
Great.
Mine: the commit sent earlier in this email thread - it's a re-back-port, as I think the original back-port for 4.14 (and similarly for 4.9) is incorrect. This has clearly not reached public git, hence my question about whether the change was queued.
I don't know what the git commit id you are looking for here, sorry. I don't have the whole thread anywhere.
These are the ids of messages containing my commits:
4.14: 20200608093950.86293-1-gprocida@google.com 4.9: 20200608094030.87031-1-gprocida@google.com
Pointers to this on lore.kernel.org perhaps?
I wasn't aware stable was publicly archived. Here you go:
4.14: https://lore.kernel.org/stable/20200608093950.86293-1-gprocida@google.com/ 4.9: https://lore.kernel.org/stable/20200608094030.87031-1-gprocida@google.com/
As per the git commit id in those emails, you should be able to determine the same thing that I can, namely that that patch is in the following stable releases: 4.4.224 4.9.219 4.14.176 4.19
Both those commits contain the text:
"Backporting Notes
This is a re-backport, landing synchronize_rcu in the right place."
If there's a special procedure for fixing back-ports, let me know, 'cos I haven't found one!
Ah, I missed that, as it was not obvious.
I can't take a patch that is a redo of a previous patch as it will not apply, right?
Send a patch saying, specifically, something like "This fixes a broken backport that was commit XXX which was commit YYY upstream..." and so on.
otherwise it gets lost in the noise as you are seeing here...
thansk,
greg k-h
linux-stable-mirror@lists.linaro.org
-
Giuliano Procida -
Greg KH