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nvmet: Fix crash when a namespace is disabled

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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: 74d16965d7 ("nvmet-loop: avoid using mutex in IO hotpath")

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Hannes Reinecke 2025-02-07 13:41:34 +01:00 • committed by Keith Busch
parent 84e009042d
commit 4082326807
1 changed files with 19 additions and 21 deletions
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40
drivers/nvme/target/core.c
View file

@ -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);