diff options
| author | Gabriel Krisman Bertazi <krisman@collabora.com> | 2020-10-22 16:58:42 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-10-26 07:57:47 -0600 |
| commit | f255c19b3ab46d3cad3b1b2e1036f4c926cb1d0c (patch) | |
| tree | 7cfc8b4e2a8ad387349116137844b81e9264cb0b /block | |
| parent | 52abfcbd57eefdd54737fc8c2dc79d8f46d4a3e5 (diff) | |
blk-cgroup: Pre-allocate tree node on blkg_conf_prep
Similarly to commit 457e490f2b741 ("blkcg: allocate struct blkcg_gq
outside request queue spinlock"), blkg_create can also trigger
occasional -ENOMEM failures at the radix insertion because any
allocation inside blkg_create has to be non-blocking, making it more
likely to fail. This causes trouble for userspace tools trying to
configure io weights who need to deal with this condition.
This patch reduces the occurrence of -ENOMEMs on this path by preloading
the radix tree element on a GFP_KERNEL context, such that we guarantee
the later non-blocking insertion won't fail.
A similar solution exists in blkcg_init_queue for the same situation.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index f9389b7cf823..c68bdf58c9a6 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -657,6 +657,12 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, goto fail; } + if (radix_tree_preload(GFP_KERNEL)) { + blkg_free(new_blkg); + ret = -ENOMEM; + goto fail; + } + rcu_read_lock(); spin_lock_irq(&q->queue_lock); @@ -664,7 +670,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, if (IS_ERR(blkg)) { ret = PTR_ERR(blkg); blkg_free(new_blkg); - goto fail_unlock; + goto fail_preloaded; } if (blkg) { @@ -673,10 +679,12 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, blkg = blkg_create(pos, q, new_blkg); if (IS_ERR(blkg)) { ret = PTR_ERR(blkg); - goto fail_unlock; + goto fail_preloaded; } } + radix_tree_preload_end(); + if (pos == blkcg) goto success; } @@ -686,6 +694,8 @@ success: ctx->body = input; return 0; +fail_preloaded: + radix_tree_preload_end(); fail_unlock: spin_unlock_irq(&q->queue_lock); rcu_read_unlock(); |