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Johannes Thumshirn authored
When running blktest's nvme/005 with a lockdep enabled kernel the test case fails due to the following lockdep splat in dmesg: ============================= WARNING: suspicious RCU usage 4.17.0-rc5 #881 Not tainted ----------------------------- drivers/nvme/host/nvme.h:457 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by kworker/u32:5/1102: #0: (ptrval) ((wq_completion)"nvme-wq"){+.+.}, at: process_one_work+0x152/0x5c0 #1: (ptrval) ((work_completion)(&ctrl->scan_work)){+.+.}, at: process_one_work+0x152/0x5c0 #2: (ptrval) (&subsys->lock#2){+.+.}, at: nvme_ns_remove+0x43/0x1c0 [nvme_core] The only caller of nvme_mpath_clear_current_path() is nvme_ns_remove() which holds the subsys lock so it's likely a false positive, but when using rcu_access_pointer(), we're telling rcu and lockdep that we're only after the pointer falue. Fixes: 32acab31 ("nvme: implement multipath access to nvme subsystems") Signed-off-by:
Johannes Thumshirn <jthumshirn@suse.de> Suggested-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Keith Busch <keith.busch@intel.com>
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