From: Dylan Yudaken dylany@fb.com
[ Upstream commit b36a2050040b2d839bdc044007cdd57101d7f881 ]
In some cases io_rsrc_ref_quiesce will call io_rsrc_node_switch_start, and then immediately flush the delayed work queue &ctx->rsrc_put_work.
However the percpu_ref_put does not immediately destroy the node, it will be called asynchronously via RCU. That ends up with io_rsrc_node_ref_zero only being called after rsrc_put_work has been flushed, and so the process ends up sleeping for 1 second unnecessarily.
This patch executes the put code immediately if we are busy quiescing.
Fixes: 4a38aed2a0a7 ("io_uring: batch reap of dead file registrations") Signed-off-by: Dylan Yudaken dylany@fb.com Link: https://lore.kernel.org/r/20220121123856.3557884-1-dylany@fb.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 15f303180d70c..698db7fb62e06 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7761,10 +7761,15 @@ static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref) struct io_ring_ctx *ctx = node->rsrc_data->ctx; unsigned long flags; bool first_add = false; + unsigned long delay = HZ;
spin_lock_irqsave(&ctx->rsrc_ref_lock, flags); node->done = true;
+ /* if we are mid-quiesce then do not delay */ + if (node->rsrc_data->quiesce) + delay = 0; + while (!list_empty(&ctx->rsrc_ref_list)) { node = list_first_entry(&ctx->rsrc_ref_list, struct io_rsrc_node, node); @@ -7777,7 +7782,7 @@ static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref) spin_unlock_irqrestore(&ctx->rsrc_ref_lock, flags);
if (first_add) - mod_delayed_work(system_wq, &ctx->rsrc_put_work, HZ); + mod_delayed_work(system_wq, &ctx->rsrc_put_work, delay); }
static struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx)