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-rw-r--r--debian/patches-rt/0284-block-blk-mq-move-blk_queue_usage_counter_release-in.patch114
1 files changed, 114 insertions, 0 deletions
diff --git a/debian/patches-rt/0284-block-blk-mq-move-blk_queue_usage_counter_release-in.patch b/debian/patches-rt/0284-block-blk-mq-move-blk_queue_usage_counter_release-in.patch
new file mode 100644
index 000000000..97f2bf9b8
--- /dev/null
+++ b/debian/patches-rt/0284-block-blk-mq-move-blk_queue_usage_counter_release-in.patch
@@ -0,0 +1,114 @@
+From 8ba3db6f9244e6911ac88380cd133f39aaba95ab Mon Sep 17 00:00:00 2001
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Tue, 13 Mar 2018 13:49:16 +0100
+Subject: [PATCH 284/347] block: blk-mq: move blk_queue_usage_counter_release()
+ into process context
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+[ Upstream commit 61c928ecf4fe200bda9b49a0813b5ba0f43995b5 ]
+
+| BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:914
+| in_atomic(): 1, irqs_disabled(): 0, pid: 255, name: kworker/u257:6
+| 5 locks held by kworker/u257:6/255:
+| #0: ("events_unbound"){.+.+.+}, at: [<ffffffff8108edf1>] process_one_work+0x171/0x5e0
+| #1: ((&entry->work)){+.+.+.}, at: [<ffffffff8108edf1>] process_one_work+0x171/0x5e0
+| #2: (&shost->scan_mutex){+.+.+.}, at: [<ffffffffa000faa3>] __scsi_add_device+0xa3/0x130 [scsi_mod]
+| #3: (&set->tag_list_lock){+.+...}, at: [<ffffffff812f09fa>] blk_mq_init_queue+0x96a/0xa50
+| #4: (rcu_read_lock_sched){......}, at: [<ffffffff8132887d>] percpu_ref_kill_and_confirm+0x1d/0x120
+| Preemption disabled at:[<ffffffff812eff76>] blk_mq_freeze_queue_start+0x56/0x70
+|
+| CPU: 2 PID: 255 Comm: kworker/u257:6 Not tainted 3.18.7-rt0+ #1
+| Workqueue: events_unbound async_run_entry_fn
+| 0000000000000003 ffff8800bc29f998 ffffffff815b3a12 0000000000000000
+| 0000000000000000 ffff8800bc29f9b8 ffffffff8109aa16 ffff8800bc29fa28
+| ffff8800bc5d1bc8 ffff8800bc29f9e8 ffffffff815b8dd4 ffff880000000000
+| Call Trace:
+| [<ffffffff815b3a12>] dump_stack+0x4f/0x7c
+| [<ffffffff8109aa16>] __might_sleep+0x116/0x190
+| [<ffffffff815b8dd4>] rt_spin_lock+0x24/0x60
+| [<ffffffff810b6089>] __wake_up+0x29/0x60
+| [<ffffffff812ee06e>] blk_mq_usage_counter_release+0x1e/0x20
+| [<ffffffff81328966>] percpu_ref_kill_and_confirm+0x106/0x120
+| [<ffffffff812eff76>] blk_mq_freeze_queue_start+0x56/0x70
+| [<ffffffff812f0000>] blk_mq_update_tag_set_depth+0x40/0xd0
+| [<ffffffff812f0a1c>] blk_mq_init_queue+0x98c/0xa50
+| [<ffffffffa000dcf0>] scsi_mq_alloc_queue+0x20/0x60 [scsi_mod]
+| [<ffffffffa000ea35>] scsi_alloc_sdev+0x2f5/0x370 [scsi_mod]
+| [<ffffffffa000f494>] scsi_probe_and_add_lun+0x9e4/0xdd0 [scsi_mod]
+| [<ffffffffa000fb26>] __scsi_add_device+0x126/0x130 [scsi_mod]
+| [<ffffffffa013033f>] ata_scsi_scan_host+0xaf/0x200 [libata]
+| [<ffffffffa012b5b6>] async_port_probe+0x46/0x60 [libata]
+| [<ffffffff810978fb>] async_run_entry_fn+0x3b/0xf0
+| [<ffffffff8108ee81>] process_one_work+0x201/0x5e0
+
+percpu_ref_kill_and_confirm() invokes blk_mq_usage_counter_release() in
+a rcu-sched region. swait based wake queue can't be used due to
+wake_up_all() usage and disabled interrupts in !RT configs (as reported
+by Corey Minyard).
+The wq_has_sleeper() check has been suggested by Peter Zijlstra.
+
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+---
+ block/blk-core.c | 12 +++++++++++-
+ include/linux/blkdev.h | 2 ++
+ 2 files changed, 13 insertions(+), 1 deletion(-)
+
+diff --git a/block/blk-core.c b/block/blk-core.c
+index 461a93c08c14..a67a50dd714a 100644
+--- a/block/blk-core.c
++++ b/block/blk-core.c
+@@ -973,12 +973,21 @@ void blk_queue_exit(struct request_queue *q)
+ percpu_ref_put(&q->q_usage_counter);
+ }
+
++static void blk_queue_usage_counter_release_wrk(struct kthread_work *work)
++{
++ struct request_queue *q =
++ container_of(work, struct request_queue, mq_pcpu_wake);
++
++ wake_up_all(&q->mq_freeze_wq);
++}
++
+ static void blk_queue_usage_counter_release(struct percpu_ref *ref)
+ {
+ struct request_queue *q =
+ container_of(ref, struct request_queue, q_usage_counter);
+
+- wake_up_all(&q->mq_freeze_wq);
++ if (wq_has_sleeper(&q->mq_freeze_wq))
++ kthread_schedule_work(&q->mq_pcpu_wake);
+ }
+
+ static void blk_rq_timed_out_timer(struct timer_list *t)
+@@ -1078,6 +1087,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id,
+ queue_flag_set_unlocked(QUEUE_FLAG_BYPASS, q);
+
+ init_waitqueue_head(&q->mq_freeze_wq);
++ kthread_init_work(&q->mq_pcpu_wake, blk_queue_usage_counter_release_wrk);
+
+ /*
+ * Init percpu_ref in atomic mode so that it's faster to shutdown.
+diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
+index 39d90bf9b5fa..5566d0049c22 100644
+--- a/include/linux/blkdev.h
++++ b/include/linux/blkdev.h
+@@ -13,6 +13,7 @@
+ #include <linux/llist.h>
+ #include <linux/timer.h>
+ #include <linux/workqueue.h>
++#include <linux/kthread.h>
+ #include <linux/pagemap.h>
+ #include <linux/backing-dev-defs.h>
+ #include <linux/wait.h>
+@@ -664,6 +665,7 @@ struct request_queue {
+ #endif
+ struct rcu_head rcu_head;
+ wait_queue_head_t mq_freeze_wq;
++ struct kthread_work mq_pcpu_wake;
+ struct percpu_ref q_usage_counter;
+ struct list_head all_q_node;
+
+--
+2.36.1
+