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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: 745f2586e7 ("iommu/vt-d: Simplify function get_domain_for_dev()")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Linux kernel
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