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authorLinus Torvalds <torvalds@linux-foundation.org>2021-12-17 11:46:07 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-12-17 11:46:07 -0800
commitfa09ca5ebce5b293ddba9b042d8fa9ed690bd91d (patch)
treedf5c5e475f48cf7a5dfa6a43c0ab8de54c3109cb /block
parentcb29eee3b28c79f26aff9e396a55bf2cb831e1d9 (diff)
parentaa97f6cdb7e92909e17c8ca63e622fcb81d57a57 (diff)
downloadlinux-fa09ca5ebce5b293ddba9b042d8fa9ed690bd91d.tar.gz
Merge tag 'block-5.16-2021-12-17' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:

 - Fix for hammering on the delayed run queue timer (me)

 - bcache regression fix for this merge window (Lin)

 - Fix a divide-by-zero in the blk-iocost code (Tejun)

* tag 'block-5.16-2021-12-17' of git://git.kernel.dk/linux-block:
  bcache: fix NULL pointer reference in cached_dev_detach_finish
  block: reduce kblockd_mod_delayed_work_on() CPU consumption
  iocost: Fix divide-by-zero on donation from low hweight cgroup
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c2
-rw-r--r--block/blk-iocost.c9
2 files changed, 10 insertions, 1 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 1378d084c770..c1833f95cb97 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1484,6 +1484,8 @@ EXPORT_SYMBOL(kblockd_schedule_work);
 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
 				unsigned long delay)
 {
+	if (!delay)
+		return queue_work_on(cpu, kblockd_workqueue, &dwork->work);
 	return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
 }
 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index a5b37cc65b17..769b64394298 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -2311,7 +2311,14 @@ static void ioc_timer_fn(struct timer_list *timer)
 			hwm = current_hweight_max(iocg);
 			new_hwi = hweight_after_donation(iocg, old_hwi, hwm,
 							 usage, &now);
-			if (new_hwi < hwm) {
+			/*
+			 * Donation calculation assumes hweight_after_donation
+			 * to be positive, a condition that a donor w/ hwa < 2
+			 * can't meet. Don't bother with donation if hwa is
+			 * below 2. It's not gonna make a meaningful difference
+			 * anyway.
+			 */
+			if (new_hwi < hwm && hwa >= 2) {
 				iocg->hweight_donating = hwa;
 				iocg->hweight_after_donation = new_hwi;
 				list_add(&iocg->surplus_list, &surpluses);