[PATCH V2 2/4] blk-mq: change gfp flags to GFP_NOIO in blk_mq_realloc_hw_ctxs

From: Jianchao Wang
Date: Fri Oct 12 2018 - 06:05:43 EST


blk_mq_realloc_hw_ctxs could be invoked during update hw queues.
At the momemt, IO is blocked. Change the gfp flags from GFP_KERNEL
to GFP_NOIO to avoid forever hang during memory allocation in
blk_mq_realloc_hw_ctxs.

Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
---
block/blk-core.c | 2 +-
block/blk-flush.c | 6 +++---
block/blk-mq.c | 17 ++++++++++-------
block/blk.h | 2 +-
4 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index cff0a60..4fe7084 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1160,7 +1160,7 @@ int blk_init_allocated_queue(struct request_queue *q)
{
WARN_ON_ONCE(q->mq_ops);

- q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size);
+ q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size, GFP_KERNEL);
if (!q->fq)
return -ENOMEM;

diff --git a/block/blk-flush.c b/block/blk-flush.c
index ce41f66..8b44b86 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -566,12 +566,12 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
EXPORT_SYMBOL(blkdev_issue_flush);

struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
- int node, int cmd_size)
+ int node, int cmd_size, gfp_t flags)
{
struct blk_flush_queue *fq;
int rq_sz = sizeof(struct request);

- fq = kzalloc_node(sizeof(*fq), GFP_KERNEL, node);
+ fq = kzalloc_node(sizeof(*fq), flags, node);
if (!fq)
goto fail;

@@ -579,7 +579,7 @@ struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
spin_lock_init(&fq->mq_flush_lock);

rq_sz = round_up(rq_sz + cmd_size, cache_line_size());
- fq->flush_rq = kzalloc_node(rq_sz, GFP_KERNEL, node);
+ fq->flush_rq = kzalloc_node(rq_sz, flags, node);
if (!fq->flush_rq)
goto fail_rq;

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 32be432..9805d6a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2193,12 +2193,12 @@ static int blk_mq_init_hctx(struct request_queue *q,
* runtime
*/
hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
- GFP_KERNEL, node);
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node);
if (!hctx->ctxs)
goto unregister_cpu_notifier;

- if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
- node))
+ if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node))
goto free_ctxs;

hctx->nr_ctx = 0;
@@ -2211,7 +2211,8 @@ static int blk_mq_init_hctx(struct request_queue *q,
set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
goto free_bitmap;

- hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
+ hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size,
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
if (!hctx->fq)
goto exit_hctx;

@@ -2519,12 +2520,14 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,

node = blk_mq_hw_queue_to_node(q->mq_map, i);
hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
- GFP_KERNEL, node);
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
+ node);
if (!hctxs[i])
break;

- if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
- node)) {
+ if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask,
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
+ node)) {
kfree(hctxs[i]);
hctxs[i] = NULL;
break;
diff --git a/block/blk.h b/block/blk.h
index 9db4e38..0f86eda 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -124,7 +124,7 @@ static inline void __blk_get_queue(struct request_queue *q)
}

struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
- int node, int cmd_size);
+ int node, int cmd_size, gfp_t flags);
void blk_free_flush_queue(struct blk_flush_queue *q);

int blk_init_rl(struct request_list *rl, struct request_queue *q,
--
2.7.4