Merge tag 'block-5.6-2020-03-07' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Here are a few fixes that should go into this release. This contains:

   - Revert of a bad bcache patch from this merge window

   - Removed unused function (Daniel)

   - Fixup for the blktrace fix from Jan from this release (Cengiz)

   - Fix of deeper level bfqq overwrite in BFQ (Carlo)"

* tag 'block-5.6-2020-03-07' of git://git.kernel.dk/linux-block:
  block, bfq: fix overwrite of bfq_group pointer in bfq_find_set_group()
  blktrace: fix dereference after null check
  Revert "bcache: ignore pending signals when creating gc and allocator thread"
  block: Remove used kblockd_schedule_work_on()

Author: torvalds

block/bfq-cgroup.c

@@ -610,12 +610,13 @@ struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
 	 */
 	entity = &bfqg->entity;
 	for_each_entity(entity) {
-		bfqg = container_of(entity, struct bfq_group, entity);
-		if (bfqg != bfqd->root_group) {
-			parent = bfqg_parent(bfqg);
+		struct bfq_group *curr_bfqg = container_of(entity,
+						struct bfq_group, entity);
+		if (curr_bfqg != bfqd->root_group) {
+			parent = bfqg_parent(curr_bfqg);
 			if (!parent)
 				parent = bfqd->root_group;
-			bfq_group_set_parent(bfqg, parent);
+			bfq_group_set_parent(curr_bfqg, parent);
 		}
 	}
 

block/blk-core.c

@@ -1663,12 +1663,6 @@ int kblockd_schedule_work(struct work_struct *work)
 }
 EXPORT_SYMBOL(kblockd_schedule_work);
 
-int kblockd_schedule_work_on(int cpu, struct work_struct *work)
-{
-	return queue_work_on(cpu, kblockd_workqueue, work);
-}
-EXPORT_SYMBOL(kblockd_schedule_work_on);
-
 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
 				unsigned long delay)
 {

drivers/md/bcache/alloc.c

@@ -67,7 +67,6 @@
 #include <linux/blkdev.h>
 #include <linux/kthread.h>
 #include <linux/random.h>
-#include <linux/sched/signal.h>
 #include <trace/events/bcache.h>
 
 #define MAX_OPEN_BUCKETS 128
@@ -734,21 +733,8 @@ int bch_open_buckets_alloc(struct cache_set *c)
 
 int bch_cache_allocator_start(struct cache *ca)
 {
-	struct task_struct *k;
-
-	/*
-	 * In case previous btree check operation occupies too many
-	 * system memory for bcache btree node cache, and the
-	 * registering process is selected by OOM killer. Here just
-	 * ignore the SIGKILL sent by OOM killer if there is, to
-	 * avoid kthread_run() being failed by pending signals. The
-	 * bcache registering process will exit after the registration
-	 * done.
-	 */
-	if (signal_pending(current))
-		flush_signals(current);
-
-	k = kthread_run(bch_allocator_thread, ca, "bcache_allocator");
+	struct task_struct *k = kthread_run(bch_allocator_thread,
+					    ca, "bcache_allocator");
 	if (IS_ERR(k))
 		return PTR_ERR(k);
 

drivers/md/bcache/btree.c

@@ -34,7 +34,6 @@
 #include <linux/random.h>
 #include <linux/rcupdate.h>
 #include <linux/sched/clock.h>
-#include <linux/sched/signal.h>
 #include <linux/rculist.h>
 #include <linux/delay.h>
 #include <trace/events/bcache.h>
@@ -1914,18 +1913,6 @@ static int bch_gc_thread(void *arg)
 
 int bch_gc_thread_start(struct cache_set *c)
 {
-	/*
-	 * In case previous btree check operation occupies too many
-	 * system memory for bcache btree node cache, and the
-	 * registering process is selected by OOM killer. Here just
-	 * ignore the SIGKILL sent by OOM killer if there is, to
-	 * avoid kthread_run() being failed by pending signals. The
-	 * bcache registering process will exit after the registration
-	 * done.
-	 */
-	if (signal_pending(current))
-		flush_signals(current);
-
 	c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
 	return PTR_ERR_OR_ZERO(c->gc_thread);
 }

include/linux/blkdev.h

@@ -1494,7 +1494,6 @@ static inline void put_dev_sector(Sector p)
 }
 
 int kblockd_schedule_work(struct work_struct *work);
-int kblockd_schedule_work_on(int cpu, struct work_struct *work);
 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, unsigned long delay);
 
 #define MODULE_ALIAS_BLOCKDEV(major,minor) \

kernel/trace/blktrace.c

@@ -1896,8 +1896,11 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
 	}
 
 	ret = 0;
-	if (bt == NULL)
+	if (bt == NULL) {
 		ret = blk_trace_setup_queue(q, bdev);
+		bt = rcu_dereference_protected(q->blk_trace,
+				lockdep_is_held(&q->blk_trace_mutex));
+	}
 
 	if (ret == 0) {
 		if (attr == &dev_attr_act_mask)