With CONFIG_INTEL_IOMMU_DEBUGFS enabled, below lockdep splat are seen
when an I/O fault occurs on a machine with an Intel IOMMU in it.
DMAR: DRHD: handling fault status reg 3
DMAR: [DMA Write NO_PASID] Request device [00:1a.0] fault addr 0x0
[fault reason 0x05] PTE Write access is not set
DMAR: Dump dmar0 table entries for IOVA 0x0
DMAR: root entry: 0x0000000127f42001
DMAR: context entry: hi 0x0000000000001502, low 0x000000012d8ab001
================================
WARNING: inconsistent lock state
5.20.0-0.rc0.20220812git7ebfc85e2cd7.10.fc38.x86_64 #1 Not tainted
--------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
rngd/1006 [HC1[1]:SC0[0]:HE0:SE1] takes:
ff177021416f2d78 (&k->k_lock){?.+.}-{2:2}, at: klist_next+0x1b/0x160
{HARDIRQ-ON-W} state was registered at:
lock_acquire+0xce/0x2d0
_raw_spin_lock+0x33/0x80
klist_add_tail+0x46/0x80
bus_add_device+0xee/0x150
device_add+0x39d/0x9a0
add_memory_block+0x108/0x1d0
memory_dev_init+0xe1/0x117
driver_init+0x43/0x4d
kernel_init_freeable+0x1c2/0x2cc
kernel_init+0x16/0x140
ret_from_fork+0x1f/0x30
irq event stamp: 7812
hardirqs last enabled at (7811): [<ffffffff85000e86>] asm_sysvec_apic_timer_interrupt+0x16/0x20
hardirqs last disabled at (7812): [<ffffffff84f16894>] irqentry_enter+0x54/0x60
softirqs last enabled at (7794): [<ffffffff840ff669>] __irq_exit_rcu+0xf9/0x170
softirqs last disabled at (7787): [<ffffffff840ff669>] __irq_exit_rcu+0xf9/0x170
The klist iterator functions using spin_*lock_irq*() but the klist
insertion functions using spin_*lock(), combined with the Intel DMAR
IOMMU driver iterating over klists from atomic (hardirq) context, where
pci_get_domain_bus_and_slot() calls into bus_find_device() which iterates
over klists.
As currently there's no plan to fix the klist to make it safe to use in
atomic context, this fixes the lockdep splat by avoid calling
pci_get_domain_bus_and_slot() in the hardirq context.
Fixes: 8ac0b64b97 ("iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk()")
Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Link: https://lore.kernel.org/linux-iommu/Yvo2dfpEh%2FWC+Wrr@wantstofly.org/
Link: https://lore.kernel.org/linux-iommu/YvyBdPwrTuHHbn5X@wantstofly.org/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20220819015949.4795-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
35bf49e054