Patch "blk-mq: Include all present CPUs in the default queue mapping" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

blk-mq: Include all present CPUs in the default queue mapping

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
blk-mq-include-all-present-cpus-in-the-default-queue-mapping.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Christoph Hellwig <[email protected]>
Date: Mon, 26 Jun 2017 12:20:56 +0200
Subject: blk-mq: Include all present CPUs in the default queue mapping

From: Christoph Hellwig <[email protected]>

commit 5f042e7cbd9ebd3580077dcdc21f35e68c2adf5f upstream.

This way we get a nice distribution independent of the current cpu online / offline state.

---
 block/blk-mq-cpumap.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

@@ -35,7 +35,6 @@ int blk_mq_map_queues(struct blk_mq_tag_
 {
 	unsigned int *map = set->mq_map;
 	unsigned int nr_queues = set->nr_hw_queues;
-	const struct cpumask *online_mask = cpu_online_mask;
 	unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
 	cpumask_var_t cpus;
 

@@ -44,7 +43,7 @@ int blk_mq_map_queues(struct blk_mq_tag_
 
 	cpumask_clear(cpus);
 	nr_cpus = nr_uniq_cpus = 0;
-	for_each_cpu(i, online_mask) {
+	for_each_present_cpu(i) {
 		nr_cpus++;
 		first_sibling = get_first_sibling(i);
 		if (!cpumask_test_cpu(first_sibling, cpus))

@@ -54,7 +53,7 @@ int blk_mq_map_queues(struct blk_mq_tag_
 
 	queue = 0;
 	for_each_possible_cpu(i) {
-		if (!cpumask_test_cpu(i, online_mask)) {
+		if (!cpumask_test_cpu(i, cpu_present_mask)) {
 			map[i] = 0;
 			continue;
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/blk-mq-include-all-present-cpus-in-the-default-queue-mapping.patch

Nah, I'm dropping this from 4.9, doesn't make sense there at the moment.

thanks,

greg k-h

Yeah, I'd feel much better if we just kept those patches are 4.12.

Jens Axboe