a349ffcb4d
The per domain spinlock is acquired in iommu_flush_dev_iotlb(), which is possbile to be called in the interrupt context. For example, the drm-intel's CI system got completely blocked with below error: WARNING: inconsistent lock state 6.0.0-rc1-CI_DRM_11990-g6590d43d39b9+ #1 Not tainted -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/6/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88810440d678 (&domain->lock){+.?.}-{2:2}, at: iommu_flush_dev_iotlb.part.61+0x23/0x80 {SOFTIRQ-ON-W} state was registered at: lock_acquire+0xd3/0x310 _raw_spin_lock+0x2a/0x40 domain_update_iommu_cap+0x20b/0x2c0 intel_iommu_attach_device+0x5bd/0x860 __iommu_attach_device+0x18/0xe0 bus_iommu_probe+0x1f3/0x2d0 bus_set_iommu+0x82/0xd0 intel_iommu_init+0xe45/0x102a pci_iommu_init+0x9/0x31 do_one_initcall+0x53/0x2f0 kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120 ret_from_fork+0x1f/0x30 irq event stamp: 162354 hardirqs last enabled at (162354): [<ffffffff81b59274>] _raw_spin_unlock_irqrestore+0x54/0x70 hardirqs last disabled at (162353): [<ffffffff81b5901b>] _raw_spin_lock_irqsave+0x4b/0x50 softirqs last enabled at (162338): [<ffffffff81e00323>] __do_softirq+0x323/0x48e softirqs last disabled at (162349): [<ffffffff810c1588>] irq_exit_rcu+0xb8/0xe0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&domain->lock); <Interrupt> lock(&domain->lock); *** DEADLOCK *** 1 lock held by swapper/6/0: This coverts the spin_lock/unlock() into the irq save/restore varieties to fix the recursive locking issues. Fixes: ffd5869d93530 ("iommu/vt-d: Replace spin_lock_irqsave() with spin_lock()") Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Acked-by: Lucas De Marchi <lucas.demarchi@intel.com> Link: https://lore.kernel.org/r/20220817025650.3253959-1-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
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.