@@ -1574,22 +1574,6 @@ static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
return NOTIFY_OK;
}
-static int blk_mq_hctx_cpu_online(struct blk_mq_hw_ctx *hctx, int cpu)
-{
- struct request_queue *q = hctx->queue;
- struct blk_mq_tag_set *set = q->tag_set;
-
- if (set->tags[hctx->queue_num])
- return NOTIFY_OK;
-
- set->tags[hctx->queue_num] = blk_mq_init_rq_map(set, hctx->queue_num);
- if (!set->tags[hctx->queue_num])
- return NOTIFY_STOP;
-
- hctx->tags = set->tags[hctx->queue_num];
- return NOTIFY_OK;
-}
-
static int blk_mq_hctx_notify(void *data, unsigned long action,
unsigned int cpu)
{
@@ -1597,8 +1581,11 @@ static int blk_mq_hctx_notify(void *data, unsigned long action,
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
return blk_mq_hctx_cpu_offline(hctx, cpu);
- else if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
- return blk_mq_hctx_cpu_online(hctx, cpu);
+
+ /*
+ * In case of CPU online, tags may be reallocated
+ * in blk_mq_map_swqueue() after mapping is updated.
+ */
return NOTIFY_OK;
}
@@ -1780,6 +1767,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
unsigned int i;
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
+ struct blk_mq_tag_set *set = q->tag_set;
queue_for_each_hw_ctx(q, hctx, i) {
cpumask_clear(hctx->cpumask);
@@ -1806,16 +1794,20 @@ static void blk_mq_map_swqueue(struct request_queue *q)
* disable it and free the request entries.
*/
if (!hctx->nr_ctx) {
- struct blk_mq_tag_set *set = q->tag_set;
-
if (set->tags[i]) {
blk_mq_free_rq_map(set, set->tags[i], i);
set->tags[i] = NULL;
- hctx->tags = NULL;
}
+ hctx->tags = NULL;
continue;
}
+ /* unmapped hw queue can be remapped after CPU topo changed */
+ if (!set->tags[i])
+ set->tags[i] = blk_mq_init_rq_map(set, i);
+ hctx->tags = set->tags[i];
+ WARN_ON(!hctx->tags);
+
/*
* Initialize batch roundrobin counts
*/
This is a note to let you know that I have just added a patch titled blk-mq: fix CPU hotplug handling to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt1. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From aed63882f9341daa73cd25be9b70f6e5963894eb Mon Sep 17 00:00:00 2001 From: Ming Lei <ming.lei@canonical.com> Date: Tue, 21 Apr 2015 10:00:20 +0800 Subject: blk-mq: fix CPU hotplug handling commit 2a34c0872adf252f23a6fef2d051a169ac796cef upstream. hctx->tags has to be set as NULL in case that it is to be unmapped no matter if set->tags[hctx->queue_num] is NULL or not in blk_mq_map_swqueue() because shared tags can be freed already from another request queue. The same situation has to be considered during handling CPU online too. Unmapped hw queue can be remapped after CPU topo is changed, so we need to allocate tags for the hw queue in blk_mq_map_swqueue(). Then tags allocation for hw queue can be removed in hctx cpu online notifier, and it is reasonable to do that after mapping is updated. Reported-by: Dongsu Park <dongsu.park@profitbricks.com> Tested-by: Dongsu Park <dongsu.park@profitbricks.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- block/blk-mq.c | 34 +++++++++++++--------------------- 1 file changed, 13 insertions(+), 21 deletions(-) -- 1.9.1