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Revision 1a3f2fd7fc4e8f24510830e265de2ffb8e3300d2 authored by Lu Baolu on 27 September 2020, 06:24:28 UTC, committed by Joerg Roedel on 01 October 2020, 12:54:17 UTC 
iommu/vt-d: Fix lockdep splat in iommu_flush_dev_iotlb()
 
Lock(&iommu->lock) without disabling irq causes lockdep warnings.

[   12.703950] ========================================================
[   12.703962] WARNING: possible irq lock inversion dependency detected
[   12.703975] 5.9.0-rc6+ #659 Not tainted
[   12.703983] --------------------------------------------------------
[   12.703995] systemd-udevd/284 just changed the state of lock:
[   12.704007] ffffffffbd6ff4d8 (device_domain_lock){..-.}-{2:2}, at:
               iommu_flush_dev_iotlb.part.57+0x2e/0x90
[   12.704031] but this lock took another, SOFTIRQ-unsafe lock in the past:
[   12.704043]  (&iommu->lock){+.+.}-{2:2}
[   12.704045]

               and interrupts could create inverse lock ordering between
               them.

[   12.704073]
               other info that might help us debug this:
[   12.704085]  Possible interrupt unsafe locking scenario:

[   12.704097]        CPU0                    CPU1
[   12.704106]        ----                    ----
[   12.704115]   lock(&iommu->lock);
[   12.704123]                                local_irq_disable();
[   12.704134]                                lock(device_domain_lock);
[   12.704146]                                lock(&iommu->lock);
[   12.704158]   <Interrupt>
[   12.704164]     lock(device_domain_lock);
[   12.704174]
                *** DEADLOCK ***

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20200927062428.13713-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
1 parent 0bbe4ce
Raw File
pgalloc-track.h 
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PGALLLC_TRACK_H
#define _LINUX_PGALLLC_TRACK_H

#if defined(CONFIG_MMU)
static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
				     unsigned long address,
				     pgtbl_mod_mask *mod_mask)
{
	if (unlikely(pgd_none(*pgd))) {
		if (__p4d_alloc(mm, pgd, address))
			return NULL;
		*mod_mask |= PGTBL_PGD_MODIFIED;
	}

	return p4d_offset(pgd, address);
}

static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
				     unsigned long address,
				     pgtbl_mod_mask *mod_mask)
{
	if (unlikely(p4d_none(*p4d))) {
		if (__pud_alloc(mm, p4d, address))
			return NULL;
		*mod_mask |= PGTBL_P4D_MODIFIED;
	}

	return pud_offset(p4d, address);
}

static inline pmd_t *pmd_alloc_track(struct mm_struct *mm, pud_t *pud,
				     unsigned long address,
				     pgtbl_mod_mask *mod_mask)
{
	if (unlikely(pud_none(*pud))) {
		if (__pmd_alloc(mm, pud, address))
			return NULL;
		*mod_mask |= PGTBL_PUD_MODIFIED;
	}

	return pmd_offset(pud, address);
}
#endif /* CONFIG_MMU */

#define pte_alloc_kernel_track(pmd, address, mask)			\
	((unlikely(pmd_none(*(pmd))) &&					\
	  (__pte_alloc_kernel(pmd) || ({*(mask)|=PGTBL_PMD_MODIFIED;0;})))?\
		NULL: pte_offset_kernel(pmd, address))

#endif /* _LINUX_PGALLLC_TRACK_H */
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