Commit 4317228a authored Apr 09, 2018 by Nitzan Carmi Committed by Paul E. McKenney May 15, 2018

nvme: Avoid flush dependency in delete controller flow



The nvme_delete_ctrl() function queues a work item on a MEM_RECLAIM
queue (nvme_delete_wq), which eventually calls cleanup_srcu_struct(),
which in turn flushes a delayed work from an !MEM_RECLAIM queue. This
is unsafe as we might trigger deadlocks under severe memory pressure.

Since we don't ever invoke call_srcu(), it is safe to use the shiny new
_quiesced() version of srcu cleanup, thus avoiding that flush dependency.
This commit makes that change.

Signed-off-by: Nitzan Carmi <nitzanc@mellanox.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>

parent f7194ac3

drivers/nvme/host/core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -349,7 +349,7 @@ static void nvme_free_ns_head(struct kref *ref)
		nvme_mpath_remove_disk(head);
		ida_simple_remove(&head->subsys->ns_ida, head->instance);
		list_del_init(&head->entry);
		cleanup_srcu_struct(&head->srcu);
		cleanup_srcu_struct_quiesced(&head->srcu);
		kfree(head);
		}

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