618fbf4c91
[ Upstream commit f6944d4a0b87c16bc34ae589169e1ded3d4db08e ] Lockdep reports the below circular locking dependency issue. The mmap_lock acquisition while holding pci_bus_sem is due to the use of copy_to_user() from within a pci_walk_bus() callback. Building the devices array directly into the user buffer is only for convenience. Instead we can allocate a local buffer for the array, bounded by the number of devices on the bus/slot, fill the device information into this local buffer, then copy it into the user buffer outside the bus walk callback. ====================================================== WARNING: possible circular locking dependency detected 6.9.0-rc5+ #39 Not tainted ------------------------------------------------------ CPU 0/KVM/4113 is trying to acquire lock: ffff99a609ee18a8 (&vdev->vma_lock){+.+.}-{4:4}, at: vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] but task is already holding lock: ffff99a243a052a0 (&mm->mmap_lock){++++}-{4:4}, at: vaddr_get_pfns+0x3f/0x170 [vfio_iommu_type1] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&mm->mmap_lock){++++}-{4:4}: __lock_acquire+0x4e4/0xb90 lock_acquire+0xbc/0x2d0 __might_fault+0x5c/0x80 _copy_to_user+0x1e/0x60 vfio_pci_fill_devs+0x9f/0x130 [vfio_pci_core] vfio_pci_walk_wrapper+0x45/0x60 [vfio_pci_core] __pci_walk_bus+0x6b/0xb0 vfio_pci_ioctl_get_pci_hot_reset_info+0x10b/0x1d0 [vfio_pci_core] vfio_pci_core_ioctl+0x1cb/0x400 [vfio_pci_core] vfio_device_fops_unl_ioctl+0x7e/0x140 [vfio] __x64_sys_ioctl+0x8a/0xc0 do_syscall_64+0x8d/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #2 (pci_bus_sem){++++}-{4:4}: __lock_acquire+0x4e4/0xb90 lock_acquire+0xbc/0x2d0 down_read+0x3e/0x160 pci_bridge_wait_for_secondary_bus.part.0+0x33/0x2d0 pci_reset_bus+0xdd/0x160 vfio_pci_dev_set_hot_reset+0x256/0x270 [vfio_pci_core] vfio_pci_ioctl_pci_hot_reset_groups+0x1a3/0x280 [vfio_pci_core] vfio_pci_core_ioctl+0x3b5/0x400 [vfio_pci_core] vfio_device_fops_unl_ioctl+0x7e/0x140 [vfio] __x64_sys_ioctl+0x8a/0xc0 do_syscall_64+0x8d/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #1 (&vdev->memory_lock){+.+.}-{4:4}: __lock_acquire+0x4e4/0xb90 lock_acquire+0xbc/0x2d0 down_write+0x3b/0xc0 vfio_pci_zap_and_down_write_memory_lock+0x1c/0x30 [vfio_pci_core] vfio_basic_config_write+0x281/0x340 [vfio_pci_core] vfio_config_do_rw+0x1fa/0x300 [vfio_pci_core] vfio_pci_config_rw+0x75/0xe50 [vfio_pci_core] vfio_pci_rw+0xea/0x1a0 [vfio_pci_core] vfs_write+0xea/0x520 __x64_sys_pwrite64+0x90/0xc0 do_syscall_64+0x8d/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (&vdev->vma_lock){+.+.}-{4:4}: check_prev_add+0xeb/0xcc0 validate_chain+0x465/0x530 __lock_acquire+0x4e4/0xb90 lock_acquire+0xbc/0x2d0 __mutex_lock+0x97/0xde0 vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] __do_fault+0x31/0x160 do_pte_missing+0x65/0x3b0 __handle_mm_fault+0x303/0x720 handle_mm_fault+0x10f/0x460 fixup_user_fault+0x7f/0x1f0 follow_fault_pfn+0x66/0x1c0 [vfio_iommu_type1] vaddr_get_pfns+0xf2/0x170 [vfio_iommu_type1] vfio_pin_pages_remote+0x348/0x4e0 [vfio_iommu_type1] vfio_pin_map_dma+0xd2/0x330 [vfio_iommu_type1] vfio_dma_do_map+0x2c0/0x440 [vfio_iommu_type1] vfio_iommu_type1_ioctl+0xc5/0x1d0 [vfio_iommu_type1] __x64_sys_ioctl+0x8a/0xc0 do_syscall_64+0x8d/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e other info that might help us debug this: Chain exists of: &vdev->vma_lock --> pci_bus_sem --> &mm->mmap_lock Possible unsafe locking scenario: block dm-0: the capability attribute has been deprecated. CPU0 CPU1 ---- ---- rlock(&mm->mmap_lock); lock(pci_bus_sem); lock(&mm->mmap_lock); lock(&vdev->vma_lock); *** DEADLOCK *** 2 locks held by CPU 0/KVM/4113: #0: ffff99a25f294888 (&iommu->lock#2){+.+.}-{4:4}, at: vfio_dma_do_map+0x60/0x440 [vfio_iommu_type1] #1: ffff99a243a052a0 (&mm->mmap_lock){++++}-{4:4}, at: vaddr_get_pfns+0x3f/0x170 [vfio_iommu_type1] stack backtrace: CPU: 1 PID: 4113 Comm: CPU 0/KVM Not tainted 6.9.0-rc5+ #39 Hardware name: Dell Inc. PowerEdge T640/04WYPY, BIOS 2.15.1 06/16/2022 Call Trace: <TASK> dump_stack_lvl+0x64/0xa0 check_noncircular+0x131/0x150 check_prev_add+0xeb/0xcc0 ? add_chain_cache+0x10a/0x2f0 ? __lock_acquire+0x4e4/0xb90 validate_chain+0x465/0x530 __lock_acquire+0x4e4/0xb90 lock_acquire+0xbc/0x2d0 ? vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] ? lock_is_held_type+0x9a/0x110 __mutex_lock+0x97/0xde0 ? vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] ? lock_acquire+0xbc/0x2d0 ? vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] ? find_held_lock+0x2b/0x80 ? vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] vfio_pci_mmap_fault+0x35/0x1a0 [vfio_pci_core] __do_fault+0x31/0x160 do_pte_missing+0x65/0x3b0 __handle_mm_fault+0x303/0x720 handle_mm_fault+0x10f/0x460 fixup_user_fault+0x7f/0x1f0 follow_fault_pfn+0x66/0x1c0 [vfio_iommu_type1] vaddr_get_pfns+0xf2/0x170 [vfio_iommu_type1] vfio_pin_pages_remote+0x348/0x4e0 [vfio_iommu_type1] vfio_pin_map_dma+0xd2/0x330 [vfio_iommu_type1] vfio_dma_do_map+0x2c0/0x440 [vfio_iommu_type1] vfio_iommu_type1_ioctl+0xc5/0x1d0 [vfio_iommu_type1] __x64_sys_ioctl+0x8a/0xc0 do_syscall_64+0x8d/0x170 ? rcu_core+0x8d/0x250 ? __lock_release+0x5e/0x160 ? rcu_core+0x8d/0x250 ? lock_release+0x5f/0x120 ? sched_clock+0xc/0x30 ? sched_clock_cpu+0xb/0x190 ? irqtime_account_irq+0x40/0xc0 ? __local_bh_enable+0x54/0x60 ? __do_softirq+0x315/0x3ca ? lockdep_hardirqs_on_prepare.part.0+0x97/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f8300d0357b Code: ff ff ff 85 c0 79 9b 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 68 0f 00 f7 d8 64 89 01 48 RSP: 002b:00007f82ef3fb948 EFLAGS: 00000206 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8300d0357b RDX: 00007f82ef3fb990 RSI: 0000000000003b71 RDI: 0000000000000023 RBP: 00007f82ef3fb9c0 R08: 0000000000000000 R09: 0000561b7e0bcac2 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000200000000 R14: 0000381800000000 R15: 0000000000000000 </TASK> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/20240503143138.3562116-1-alex.williamson@redhat.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
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