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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
cma.h 
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __MM_CMA_H__
#define __MM_CMA_H__

#include <linux/debugfs.h>

#define CMA_MAX_NAME 64

struct cma {
	unsigned long   base_pfn;
	unsigned long   count;
	unsigned long   *bitmap;
	unsigned int order_per_bit; /* Order of pages represented by one bit */
	struct mutex    lock;
#ifdef CONFIG_CMA_DEBUGFS
	struct hlist_head mem_head;
	spinlock_t mem_head_lock;
	struct debugfs_u32_array dfs_bitmap;
#endif
	char name[CMA_MAX_NAME];
};

extern struct cma cma_areas[MAX_CMA_AREAS];
extern unsigned cma_area_count;

static inline unsigned long cma_bitmap_maxno(struct cma *cma)
{
	return cma->count >> cma->order_per_bit;
}

#endif
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