diff mbox

[RESEND,v2,2/2] blk-mq: Avoid memory reclaim when remapping queues

Message ID 1481038304-22502-2-git-send-email-krisman@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Gabriel Krisman Bertazi Dec. 6, 2016, 3:31 p.m. UTC 
While stressing memory and IO at the same time we changed SMT settings,
we were able to consistently trigger deadlocks in the mm system, which
froze the entire machine.

I think that under memory stress conditions, the large allocations
performed by blk_mq_init_rq_map may trigger a reclaim, which stalls
waiting on the block layer remmaping completion, thus deadlocking the
system.  The trace below was collected after the machine stalled,
waiting for the hotplug event completion.

The simplest fix for this is to make allocations in this path
non-reclaimable, with GFP_NOIO.  With this patch, We couldn't hit the
issue anymore.

This should apply on top of Jen's for-next branch cleanly.

Changes since v1:
  - Use GFP_NOIO instead of GFP_NOWAIT.

 Call Trace:
[c000000f0160aaf0] [c000000f0160ab50] 0xc000000f0160ab50 (unreliable)
[c000000f0160acc0] [c000000000016624] __switch_to+0x2e4/0x430
[c000000f0160ad20] [c000000000b1a880] __schedule+0x310/0x9b0
[c000000f0160ae00] [c000000000b1af68] schedule+0x48/0xc0
[c000000f0160ae30] [c000000000b1b4b0] schedule_preempt_disabled+0x20/0x30
[c000000f0160ae50] [c000000000b1d4fc] __mutex_lock_slowpath+0xec/0x1f0
[c000000f0160aed0] [c000000000b1d678] mutex_lock+0x78/0xa0
[c000000f0160af00] [d000000019413cac] xfs_reclaim_inodes_ag+0x33c/0x380 [xfs]
[c000000f0160b0b0] [d000000019415164] xfs_reclaim_inodes_nr+0x54/0x70 [xfs]
[c000000f0160b0f0] [d0000000194297f8] xfs_fs_free_cached_objects+0x38/0x60 [xfs]
[c000000f0160b120] [c0000000003172c8] super_cache_scan+0x1f8/0x210
[c000000f0160b190] [c00000000026301c] shrink_slab.part.13+0x21c/0x4c0
[c000000f0160b2d0] [c000000000268088] shrink_zone+0x2d8/0x3c0
[c000000f0160b380] [c00000000026834c] do_try_to_free_pages+0x1dc/0x520
[c000000f0160b450] [c00000000026876c] try_to_free_pages+0xdc/0x250
[c000000f0160b4e0] [c000000000251978] __alloc_pages_nodemask+0x868/0x10d0
[c000000f0160b6f0] [c000000000567030] blk_mq_init_rq_map+0x160/0x380
[c000000f0160b7a0] [c00000000056758c] blk_mq_map_swqueue+0x33c/0x360
[c000000f0160b820] [c000000000567904] blk_mq_queue_reinit+0x64/0xb0
[c000000f0160b850] [c00000000056a16c] blk_mq_queue_reinit_notify+0x19c/0x250
[c000000f0160b8a0] [c0000000000f5d38] notifier_call_chain+0x98/0x100
[c000000f0160b8f0] [c0000000000c5fb0] __cpu_notify+0x70/0xe0
[c000000f0160b930] [c0000000000c63c4] notify_prepare+0x44/0xb0
[c000000f0160b9b0] [c0000000000c52f4] cpuhp_invoke_callback+0x84/0x250
[c000000f0160ba10] [c0000000000c570c] cpuhp_up_callbacks+0x5c/0x120
[c000000f0160ba60] [c0000000000c7cb8] _cpu_up+0xf8/0x1d0
[c000000f0160bac0] [c0000000000c7eb0] do_cpu_up+0x120/0x150
[c000000f0160bb40] [c0000000006fe024] cpu_subsys_online+0x64/0xe0
[c000000f0160bb90] [c0000000006f5124] device_online+0xb4/0x120
[c000000f0160bbd0] [c0000000006f5244] online_store+0xb4/0xc0
[c000000f0160bc20] [c0000000006f0a68] dev_attr_store+0x68/0xa0
[c000000f0160bc60] [c0000000003ccc30] sysfs_kf_write+0x80/0xb0
[c000000f0160bca0] [c0000000003cbabc] kernfs_fop_write+0x17c/0x250
[c000000f0160bcf0] [c00000000030fe6c] __vfs_write+0x6c/0x1e0
[c000000f0160bd90] [c000000000311490] vfs_write+0xd0/0x270
[c000000f0160bde0] [c0000000003131fc] SyS_write+0x6c/0x110
[c000000f0160be30] [c000000000009204] system_call+0x38/0xec

Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Cc: Douglas Miller <dougmill@linux.vnet.ibm.com>
Cc: linux-block@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
---
 block/blk-mq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Douglas Miller Dec. 7, 2016, 8:10 p.m. UTC | #1 
On 12/06/2016 09:31 AM, Gabriel Krisman Bertazi wrote:
> While stressing memory and IO at the same time we changed SMT settings,
> we were able to consistently trigger deadlocks in the mm system, which
> froze the entire machine.
>
> I think that under memory stress conditions, the large allocations
> performed by blk_mq_init_rq_map may trigger a reclaim, which stalls
> waiting on the block layer remmaping completion, thus deadlocking the
> system.  The trace below was collected after the machine stalled,
> waiting for the hotplug event completion.
>
> The simplest fix for this is to make allocations in this path
> non-reclaimable, with GFP_NOIO.  With this patch, We couldn't hit the
> issue anymore.
>
> This should apply on top of Jen's for-next branch cleanly.
>
> Changes since v1:
>    - Use GFP_NOIO instead of GFP_NOWAIT.
>
>   Call Trace:
> [c000000f0160aaf0] [c000000f0160ab50] 0xc000000f0160ab50 (unreliable)
> [c000000f0160acc0] [c000000000016624] __switch_to+0x2e4/0x430
> [c000000f0160ad20] [c000000000b1a880] __schedule+0x310/0x9b0
> [c000000f0160ae00] [c000000000b1af68] schedule+0x48/0xc0
> [c000000f0160ae30] [c000000000b1b4b0] schedule_preempt_disabled+0x20/0x30
> [c000000f0160ae50] [c000000000b1d4fc] __mutex_lock_slowpath+0xec/0x1f0
> [c000000f0160aed0] [c000000000b1d678] mutex_lock+0x78/0xa0
> [c000000f0160af00] [d000000019413cac] xfs_reclaim_inodes_ag+0x33c/0x380 [xfs]
> [c000000f0160b0b0] [d000000019415164] xfs_reclaim_inodes_nr+0x54/0x70 [xfs]
> [c000000f0160b0f0] [d0000000194297f8] xfs_fs_free_cached_objects+0x38/0x60 [xfs]
> [c000000f0160b120] [c0000000003172c8] super_cache_scan+0x1f8/0x210
> [c000000f0160b190] [c00000000026301c] shrink_slab.part.13+0x21c/0x4c0
> [c000000f0160b2d0] [c000000000268088] shrink_zone+0x2d8/0x3c0
> [c000000f0160b380] [c00000000026834c] do_try_to_free_pages+0x1dc/0x520
> [c000000f0160b450] [c00000000026876c] try_to_free_pages+0xdc/0x250
> [c000000f0160b4e0] [c000000000251978] __alloc_pages_nodemask+0x868/0x10d0
> [c000000f0160b6f0] [c000000000567030] blk_mq_init_rq_map+0x160/0x380
> [c000000f0160b7a0] [c00000000056758c] blk_mq_map_swqueue+0x33c/0x360
> [c000000f0160b820] [c000000000567904] blk_mq_queue_reinit+0x64/0xb0
> [c000000f0160b850] [c00000000056a16c] blk_mq_queue_reinit_notify+0x19c/0x250
> [c000000f0160b8a0] [c0000000000f5d38] notifier_call_chain+0x98/0x100
> [c000000f0160b8f0] [c0000000000c5fb0] __cpu_notify+0x70/0xe0
> [c000000f0160b930] [c0000000000c63c4] notify_prepare+0x44/0xb0
> [c000000f0160b9b0] [c0000000000c52f4] cpuhp_invoke_callback+0x84/0x250
> [c000000f0160ba10] [c0000000000c570c] cpuhp_up_callbacks+0x5c/0x120
> [c000000f0160ba60] [c0000000000c7cb8] _cpu_up+0xf8/0x1d0
> [c000000f0160bac0] [c0000000000c7eb0] do_cpu_up+0x120/0x150
> [c000000f0160bb40] [c0000000006fe024] cpu_subsys_online+0x64/0xe0
> [c000000f0160bb90] [c0000000006f5124] device_online+0xb4/0x120
> [c000000f0160bbd0] [c0000000006f5244] online_store+0xb4/0xc0
> [c000000f0160bc20] [c0000000006f0a68] dev_attr_store+0x68/0xa0
> [c000000f0160bc60] [c0000000003ccc30] sysfs_kf_write+0x80/0xb0
> [c000000f0160bca0] [c0000000003cbabc] kernfs_fop_write+0x17c/0x250
> [c000000f0160bcf0] [c00000000030fe6c] __vfs_write+0x6c/0x1e0
> [c000000f0160bd90] [c000000000311490] vfs_write+0xd0/0x270
> [c000000f0160bde0] [c0000000003131fc] SyS_write+0x6c/0x110
> [c000000f0160be30] [c000000000009204] system_call+0x38/0xec
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
> Cc: Brian King <brking@linux.vnet.ibm.com>
> Cc: Douglas Miller <dougmill@linux.vnet.ibm.com>
> Cc: linux-block@vger.kernel.org
> Cc: linux-scsi@vger.kernel.org
> ---
>   block/blk-mq.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 6718f894fbe1..5f4e452eef72 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1605,7 +1605,7 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
>   	INIT_LIST_HEAD(&tags->page_list);
>
>   	tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
> -				 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
> +				 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
>   				 set->numa_node);
>   	if (!tags->rqs) {
>   		blk_mq_free_tags(tags);
> @@ -1631,7 +1631,7 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
>
>   		do {
>   			page = alloc_pages_node(set->numa_node,
> -				GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
> +				GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
>   				this_order);
>   			if (page)
>   				break;
> @@ -1652,7 +1652,7 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
>   		 * Allow kmemleak to scan these pages as they contain pointers
>   		 * to additional allocations like via ops->init_request().
>   		 */
> -		kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
> +		kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
>   		entries_per_page = order_to_size(this_order) / rq_size;
>   		to_do = min(entries_per_page, set->queue_depth - i);
>   		left -= to_do * rq_size;
Reviewed-by: Douglas Miller <dougmill@linux.vnet.ibm.com>

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Jens Axboe Dec. 14, 2016, 3:14 p.m. UTC | #2 
On 12/06/2016 08:31 AM, Gabriel Krisman Bertazi wrote:
> While stressing memory and IO at the same time we changed SMT settings,
> we were able to consistently trigger deadlocks in the mm system, which
> froze the entire machine.
> 
> I think that under memory stress conditions, the large allocations
> performed by blk_mq_init_rq_map may trigger a reclaim, which stalls
> waiting on the block layer remmaping completion, thus deadlocking the
> system.  The trace below was collected after the machine stalled,
> waiting for the hotplug event completion.
> 
> The simplest fix for this is to make allocations in this path
> non-reclaimable, with GFP_NOIO.  With this patch, We couldn't hit the
> issue anymore.

This looks fine.
diff mbox

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6718f894fbe1..5f4e452eef72 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1605,7 +1605,7 @@  static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
 	INIT_LIST_HEAD(&tags->page_list);
 
 	tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
-				 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
+				 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
 				 set->numa_node);
 	if (!tags->rqs) {
 		blk_mq_free_tags(tags);
@@ -1631,7 +1631,7 @@  static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
 
 		do {
 			page = alloc_pages_node(set->numa_node,
-				GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
+				GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
 				this_order);
 			if (page)
 				break;
@@ -1652,7 +1652,7 @@  static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
 		 * Allow kmemleak to scan these pages as they contain pointers
 		 * to additional allocations like via ops->init_request().
 		 */
-		kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
+		kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
 		entries_per_page = order_to_size(this_order) / rq_size;
 		to_do = min(entries_per_page, set->queue_depth - i);
 		left -= to_do * rq_size;