2121db0963
The following lockdep splat results from acquiring the init_mutex in
acpi_nfit_clear_to_send():
WARNING: possible circular locking dependency detected
lt-daxdev-error/7216 is trying to acquire lock:
00000000f694db15 (&acpi_desc->init_mutex){+.+.}, at: acpi_nfit_clear_to_send+0x27/0x80 [nfit]
but task is already holding lock:
00000000182298f2 (&nvdimm_bus->reconfig_mutex){+.+.}, at: __nd_ioctl+0x457/0x610 [libnvdimm]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&nvdimm_bus->reconfig_mutex){+.+.}:
nvdimm_badblocks_populate+0x41/0x150 [libnvdimm]
nd_region_notify+0x95/0xb0 [libnvdimm]
nd_device_notify+0x40/0x50 [libnvdimm]
ars_complete+0x7f/0xd0 [nfit]
acpi_nfit_scrub+0xbb/0x410 [nfit]
process_one_work+0x22b/0x5c0
worker_thread+0x3c/0x390
kthread+0x11e/0x140
ret_from_fork+0x3a/0x50
-> #0 (&acpi_desc->init_mutex){+.+.}:
__mutex_lock+0x83/0x980
acpi_nfit_clear_to_send+0x27/0x80 [nfit]
__nd_ioctl+0x474/0x610 [libnvdimm]
nd_ioctl+0xa4/0xb0 [libnvdimm]
do_vfs_ioctl+0xa5/0x6e0
ksys_ioctl+0x70/0x80
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x60/0x210
entry_SYSCALL_64_after_hwframe+0x49/0xbe
New infrastructure is needed to be able to perform this check without
acquiring the lock.
Fixes: 594861215c83 ("acpi, nfit: Further restrict userspace ARS start")
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.