mainlining shenanigans
7560cc3ca7
Lockdep debug reported lock inversion related with the iommu code
caused by dmar_insert_one_dev_info() grabbing the iommu->lock and
the device_domain_lock out of order versus the code path in
iommu_flush_dev_iotlb(). Expanding the scope of the iommu->lock and
reversing the order of lock acquisition fixes the issue.
[ 76.238180] dsa_bus wq0.0: dsa wq wq0.0 disabled
[ 76.248706]
[ 76.250486] ========================================================
[ 76.257113] WARNING: possible irq lock inversion dependency detected
[ 76.263736] 5.1.0-rc5+ #162 Not tainted
[ 76.267854] --------------------------------------------------------
[ 76.274485] systemd-journal/521 just changed the state of lock:
[ 76.280685] 0000000055b330f5 (device_domain_lock){..-.}, at: iommu_flush_dev_iotlb.part.63+0x29/0x90
[ 76.290099] but this lock took another, SOFTIRQ-unsafe lock in the past:
[ 76.297093] (&(&iommu->lock)->rlock){+.+.}
[ 76.297094]
[ 76.297094]
[ 76.297094] and interrupts could create inverse lock ordering between them.
[ 76.297094]
[ 76.314257]
[ 76.314257] other info that might help us debug this:
[ 76.321448] Possible interrupt unsafe locking scenario:
[ 76.321448]
[ 76.328907] CPU0 CPU1
[ 76.333777] ---- ----
[ 76.338642] lock(&(&iommu->lock)->rlock);
[ 76.343165] local_irq_disable();
[ 76.349422] lock(device_domain_lock);
[ 76.356116] lock(&(&iommu->lock)->rlock);
[ 76.363154] <Interrupt>
[ 76.366134] lock(device_domain_lock);
[ 76.370548]
[ 76.370548] *** DEADLOCK ***
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| 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.