Commit 40823268 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Keith Busch
Browse files

nvmet: Fix crash when a namespace is disabled 



The namespace percpu counter protects pending I/O, and we can
only safely diable the namespace once the counter drop to zero.
Otherwise we end up with a crash when running blktests/nvme/058
(eg for loop transport):

[ 2352.930426] [  T53909] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN PTI
[ 2352.930431] [  T53909] KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
[ 2352.930434] [  T53909] CPU: 3 UID: 0 PID: 53909 Comm: kworker/u16:5 Tainted: G        W          6.13.0-rc6 #232
[ 2352.930438] [  T53909] Tainted: [W]=WARN
[ 2352.930440] [  T53909] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
[ 2352.930443] [  T53909] Workqueue: nvmet-wq nvme_loop_execute_work [nvme_loop]
[ 2352.930449] [  T53909] RIP: 0010:blkcg_set_ioprio+0x44/0x180

as the queue is already torn down when calling submit_bio();

So we need to init the percpu counter in nvmet_ns_enable(), and
wait for it to drop to zero in nvmet_ns_disable() to avoid having
I/O pending after the namespace has been disabled.

Fixes: 74d16965 ("nvmet-loop: avoid using mutex in IO hotpath")

Signed-off-by: default avatarHannes Reinecke <hare@kernel.org>
Reviewed-by: default avatarNilay Shroff <nilay@linux.ibm.com>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarChaitanya Kulkarni <kch@nvidia.com>
Tested-by: default avatarShin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent 84e00904

drivers/nvme/target/core.c

+19 −21
Original line number Diff line number Diff line
@@ -606,6 +606,9 @@ int nvmet_ns_enable(struct nvmet_ns *ns) 
			goto out_dev_put;

	}



	if (percpu_ref_init(&ns->ref, nvmet_destroy_namespace, 0, GFP_KERNEL))

		goto out_pr_exit;



	nvmet_ns_changed(subsys, ns->nsid);

	ns->enabled = true;

	xa_set_mark(&subsys->namespaces, ns->nsid, NVMET_NS_ENABLED);
@@ -613,6 +616,9 @@ int nvmet_ns_enable(struct nvmet_ns *ns) 
out_unlock:

	mutex_unlock(&subsys->lock);

	return ret;

out_pr_exit:

	if (ns->pr.enable)

		nvmet_pr_exit_ns(ns);

out_dev_put:

	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)

		pci_dev_put(radix_tree_delete(&ctrl->p2p_ns_map, ns->nsid));
@@ -638,6 +644,19 @@ void nvmet_ns_disable(struct nvmet_ns *ns) 


	mutex_unlock(&subsys->lock);



	/*

	 * Now that we removed the namespaces from the lookup list, we

	 * can kill the per_cpu ref and wait for any remaining references

	 * to be dropped, as well as a RCU grace period for anyone only

	 * using the namepace under rcu_read_lock().  Note that we can't

	 * use call_rcu here as we need to ensure the namespaces have

	 * been fully destroyed before unloading the module.

	 */

	percpu_ref_kill(&ns->ref);

	synchronize_rcu();

	wait_for_completion(&ns->disable_done);

	percpu_ref_exit(&ns->ref);



	if (ns->pr.enable)

		nvmet_pr_exit_ns(ns);
@@ -660,22 +679,6 @@ void nvmet_ns_free(struct nvmet_ns *ns) 
	if (ns->nsid == subsys->max_nsid)

		subsys->max_nsid = nvmet_max_nsid(subsys);



	mutex_unlock(&subsys->lock);



	/*

	 * Now that we removed the namespaces from the lookup list, we

	 * can kill the per_cpu ref and wait for any remaining references

	 * to be dropped, as well as a RCU grace period for anyone only

	 * using the namepace under rcu_read_lock().  Note that we can't

	 * use call_rcu here as we need to ensure the namespaces have

	 * been fully destroyed before unloading the module.

	 */

	percpu_ref_kill(&ns->ref);

	synchronize_rcu();

	wait_for_completion(&ns->disable_done);

	percpu_ref_exit(&ns->ref);



	mutex_lock(&subsys->lock);

	subsys->nr_namespaces--;

	mutex_unlock(&subsys->lock);
@@ -705,9 +708,6 @@ struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid) 
	ns->nsid = nsid;

	ns->subsys = subsys;



	if (percpu_ref_init(&ns->ref, nvmet_destroy_namespace, 0, GFP_KERNEL))

		goto out_free;



	if (ns->nsid > subsys->max_nsid)

		subsys->max_nsid = nsid;
@@ -730,8 +730,6 @@ struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid) 
	return ns;

out_exit:

	subsys->max_nsid = nvmet_max_nsid(subsys);

	percpu_ref_exit(&ns->ref);

out_free:

	kfree(ns);

out_unlock:

	mutex_unlock(&subsys->lock);