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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:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
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| usr | ||
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| .clang-format | ||
| .cocciconfig | ||
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| .gitignore | ||
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| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| Makefile | ||
| README | ||
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.