Vishal Verma 8e833fe47f ACPI: NFIT: fix a potential deadlock during NFIT teardown ... [ Upstream commit fb6df4366f ] Lockdep reports that acpi_nfit_shutdown() may deadlock against an opportune acpi_nfit_scrub(). acpi_nfit_scrub () is run from inside a 'work' and therefore has already acquired workqueue-internal locks. It also acquiires acpi_desc->init_mutex. acpi_nfit_shutdown() first acquires init_mutex, and was subsequently attempting to cancel any pending workqueue items. This reversed locking order causes a potential deadlock: ====================================================== WARNING: possible circular locking dependency detected 6.2.0-rc3 #116 Tainted: G O N ------------------------------------------------------ libndctl/1958 is trying to acquire lock: ffff888129b461c0 ((work_completion)(&(&acpi_desc->dwork)->work)){+.+.}-{0:0}, at: __flush_work+0x43/0x450 but task is already holding lock: ffff888129b460e8 (&acpi_desc->init_mutex){+.+.}-{3:3}, at: acpi_nfit_shutdown+0x87/0xd0 [nfit] which lock already depends on the new lock. ... Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&acpi_desc->init_mutex); lock((work_completion)(&(&acpi_desc->dwork)->work)); lock(&acpi_desc->init_mutex); lock((work_completion)(&(&acpi_desc->dwork)->work)); *** DEADLOCK *** Since the workqueue manipulation is protected by its own internal locking, the cancellation of pending work doesn't need to be done under acpi_desc->init_mutex. Move cancel_delayed_work_sync() outside the init_mutex to fix the deadlock. Any work that starts after acpi_nfit_shutdown() drops the lock will see ARS_CANCEL, and the cancel_delayed_work_sync() will safely flush it out. Reported-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> Link: https://lore.kernel.org/r/20230112-acpi_nfit_lockdep-v1-1-660be4dd10be@intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-03-03 11:44:50 +01:00
..
Kconfig	…
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
core.c	ACPI: NFIT: fix a potential deadlock during NFIT teardown	2023-03-03 11:44:50 +01:00
intel.c	ACPI: NFIT: Add runtime firmware activate support	2020-07-28 19:29:22 -06:00
intel.h	ACPI: NFIT: Add runtime firmware activate support	2020-07-28 19:29:22 -06:00
mce.c	x86/mce: Fix all mce notifiers to update the mce->kflags bitmask	2020-04-14 15:59:26 +02:00
nfit.h	libnvdimm for 5.9	2020-08-11 10:59:19 -07:00