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author | Dan Williams <dan.j.williams@intel.com> | 2017-04-30 06:57:01 -0700 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2017-05-01 13:14:37 -0700 |
commit | 565851c972b50612f3a4542e26879ffb3e906fc2 (patch) | |
tree | 88c724ad5e0a8fc3fc4c6c4479cc2f4e31377f9c /drivers/nvdimm/region_devs.c | |
parent | a3e9af95f794d000debc2a5ba3186ba85a6e115f (diff) | |
download | linux-565851c972b50612f3a4542e26879ffb3e906fc2.tar.bz2 |
device-dax: fix sysfs attribute deadlock
Usage of device_lock() for dax_region attributes is unnecessary and
deadlock prone. It's unnecessary because the order of registration /
un-registration guarantees that drvdata is always valid. It's deadlock
prone because it sets up this situation:
ndctl D 0 2170 2082 0x00000000
Call Trace:
__schedule+0x31f/0x980
schedule+0x3d/0x90
schedule_preempt_disabled+0x15/0x20
__mutex_lock+0x402/0x980
? __mutex_lock+0x158/0x980
? align_show+0x2b/0x80 [dax]
? kernfs_seq_start+0x2f/0x90
mutex_lock_nested+0x1b/0x20
align_show+0x2b/0x80 [dax]
dev_attr_show+0x20/0x50
ndctl D 0 2186 2079 0x00000000
Call Trace:
__schedule+0x31f/0x980
schedule+0x3d/0x90
__kernfs_remove+0x1f6/0x340
? kernfs_remove_by_name_ns+0x45/0xa0
? remove_wait_queue+0x70/0x70
kernfs_remove_by_name_ns+0x45/0xa0
remove_files.isra.1+0x35/0x70
sysfs_remove_group+0x44/0x90
sysfs_remove_groups+0x2e/0x50
dax_region_unregister+0x25/0x40 [dax]
devm_action_release+0xf/0x20
release_nodes+0x16d/0x2b0
devres_release_all+0x3c/0x60
device_release_driver_internal+0x17d/0x220
device_release_driver+0x12/0x20
unbind_store+0x112/0x160
ndctl/2170 is trying to acquire the device_lock() to read an attribute,
and ndctl/2186 is holding the device_lock() while trying to drain all
active attribute readers.
Thanks to Yi Zhang for the reproduction script.
Fixes: d7fe1a67f658 ("dax: add region 'id', 'size', and 'align' attributes")
Cc: <stable@vger.kernel.org>
Reported-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm/region_devs.c')
0 files changed, 0 insertions, 0 deletions