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authorDan Williams <dan.j.williams@intel.com>2019-07-17 18:08:21 -0700
committerDan Williams <dan.j.williams@intel.com>2019-07-18 16:23:16 -0700
commitca6bf264f6d856f959c4239cda1047b587745c67 (patch)
tree4f8cbf326fb06844c3db9fcdbabe0644d515e651 /drivers/nvdimm/bus.c
parentb70d31d054ee3a6fc1034b9d7fc0ae1e481aa018 (diff)
libnvdimm/bus: Fix wait_nvdimm_bus_probe_idle() ABBA deadlock
A multithreaded namespace creation/destruction stress test currently deadlocks with the following lockup signature: INFO: task ndctl:2924 blocked for more than 122 seconds. Tainted: G OE 5.2.0-rc4+ #3382 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ndctl D 0 2924 1176 0x00000000 Call Trace: ? __schedule+0x27e/0x780 schedule+0x30/0xb0 wait_nvdimm_bus_probe_idle+0x8a/0xd0 [libnvdimm] ? finish_wait+0x80/0x80 uuid_store+0xe6/0x2e0 [libnvdimm] kernfs_fop_write+0xf0/0x1a0 vfs_write+0xb7/0x1b0 ksys_write+0x5c/0xd0 do_syscall_64+0x60/0x240 INFO: task ndctl:2923 blocked for more than 122 seconds. Tainted: G OE 5.2.0-rc4+ #3382 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ndctl D 0 2923 1175 0x00000000 Call Trace: ? __schedule+0x27e/0x780 ? __mutex_lock+0x489/0x910 schedule+0x30/0xb0 schedule_preempt_disabled+0x11/0x20 __mutex_lock+0x48e/0x910 ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] ? __lock_acquire+0x23f/0x1710 ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] __dax_pmem_probe+0x5e/0x210 [dax_pmem_core] ? nvdimm_bus_probe+0x1d0/0x2c0 [libnvdimm] dax_pmem_probe+0xc/0x20 [dax_pmem] nvdimm_bus_probe+0x90/0x2c0 [libnvdimm] really_probe+0xef/0x390 driver_probe_device+0xb4/0x100 In this sequence an 'nd_dax' device is being probed and trying to take the lock on its backing namespace to validate that the 'nd_dax' device indeed has exclusive access to the backing namespace. Meanwhile, another thread is trying to update the uuid property of that same backing namespace. So one thread is in the probe path trying to acquire the lock, and the other thread has acquired the lock and tries to flush the probe path. Fix this deadlock by not holding the namespace device_lock over the wait_nvdimm_bus_probe_idle() synchronization step. In turn this requires the device_lock to be held on entry to wait_nvdimm_bus_probe_idle() and subsequently dropped internally to wait_nvdimm_bus_probe_idle(). Cc: <stable@vger.kernel.org> Fixes: bf9bccc14c05 ("libnvdimm: pmem label sets and namespace instantiation") Cc: Vishal Verma <vishal.l.verma@intel.com> Tested-by: Jane Chu <jane.chu@oracle.com> Link: https://lore.kernel.org/r/156341210094.292348.2384694131126767789.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm/bus.c')
-rw-r--r--drivers/nvdimm/bus.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index a38572bf486b..df41f3571dc9 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -887,10 +887,12 @@ void wait_nvdimm_bus_probe_idle(struct device *dev)
do {
if (nvdimm_bus->probe_active == 0)
break;
- nvdimm_bus_unlock(&nvdimm_bus->dev);
+ nvdimm_bus_unlock(dev);
+ device_unlock(dev);
wait_event(nvdimm_bus->wait,
nvdimm_bus->probe_active == 0);
- nvdimm_bus_lock(&nvdimm_bus->dev);
+ device_lock(dev);
+ nvdimm_bus_lock(dev);
} while (true);
}
@@ -1016,7 +1018,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
case ND_CMD_ARS_START:
case ND_CMD_CLEAR_ERROR:
case ND_CMD_CALL:
- dev_dbg(&nvdimm_bus->dev, "'%s' command while read-only.\n",
+ dev_dbg(dev, "'%s' command while read-only.\n",
nvdimm ? nvdimm_cmd_name(cmd)
: nvdimm_bus_cmd_name(cmd));
return -EPERM;
@@ -1105,7 +1107,8 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
goto out;
}
- nvdimm_bus_lock(&nvdimm_bus->dev);
+ device_lock(dev);
+ nvdimm_bus_lock(dev);
rc = nd_cmd_clear_to_send(nvdimm_bus, nvdimm, func, buf);
if (rc)
goto out_unlock;
@@ -1125,7 +1128,8 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
rc = -EFAULT;
out_unlock:
- nvdimm_bus_unlock(&nvdimm_bus->dev);
+ nvdimm_bus_unlock(dev);
+ device_unlock(dev);
out:
kfree(in_env);
kfree(out_env);