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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
hwpoison-inject.c 
// SPDX-License-Identifier: GPL-2.0-only
/* Inject a hwpoison memory failure on a arbitrary pfn */
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/hugetlb.h>
#include "internal.h"

static struct dentry *hwpoison_dir;

static int hwpoison_inject(void *data, u64 val)
{
	unsigned long pfn = val;
	struct page *p;
	struct page *hpage;
	int err;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	if (!pfn_valid(pfn))
		return -ENXIO;

	p = pfn_to_page(pfn);
	hpage = compound_head(p);
	/*
	 * This implies unable to support free buddy pages.
	 */
	if (!get_hwpoison_page(p))
		return 0;

	if (!hwpoison_filter_enable)
		goto inject;

	shake_page(hpage, 0);
	/*
	 * This implies unable to support non-LRU pages.
	 */
	if (!PageLRU(hpage) && !PageHuge(p))
		goto put_out;

	/*
	 * do a racy check with elevated page count, to make sure PG_hwpoison
	 * will only be set for the targeted owner (or on a free page).
	 * memory_failure() will redo the check reliably inside page lock.
	 */
	err = hwpoison_filter(hpage);
	if (err)
		goto put_out;

inject:
	pr_info("Injecting memory failure at pfn %#lx\n", pfn);
	return memory_failure(pfn, MF_COUNT_INCREASED);
put_out:
	put_hwpoison_page(p);
	return 0;
}

static int hwpoison_unpoison(void *data, u64 val)
{
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	return unpoison_memory(val);
}

DEFINE_DEBUGFS_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
DEFINE_DEBUGFS_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");

static void pfn_inject_exit(void)
{
	debugfs_remove_recursive(hwpoison_dir);
}

static int pfn_inject_init(void)
{
	hwpoison_dir = debugfs_create_dir("hwpoison", NULL);

	/*
	 * Note that the below poison/unpoison interfaces do not involve
	 * hardware status change, hence do not require hardware support.
	 * They are mainly for testing hwpoison in software level.
	 */
	debugfs_create_file("corrupt-pfn", 0200, hwpoison_dir, NULL,
			    &hwpoison_fops);

	debugfs_create_file("unpoison-pfn", 0200, hwpoison_dir, NULL,
			    &unpoison_fops);

	debugfs_create_u32("corrupt-filter-enable", 0600, hwpoison_dir,
			   &hwpoison_filter_enable);

	debugfs_create_u32("corrupt-filter-dev-major", 0600, hwpoison_dir,
			   &hwpoison_filter_dev_major);

	debugfs_create_u32("corrupt-filter-dev-minor", 0600, hwpoison_dir,
			   &hwpoison_filter_dev_minor);

	debugfs_create_u64("corrupt-filter-flags-mask", 0600, hwpoison_dir,
			   &hwpoison_filter_flags_mask);

	debugfs_create_u64("corrupt-filter-flags-value", 0600, hwpoison_dir,
			   &hwpoison_filter_flags_value);

#ifdef CONFIG_MEMCG
	debugfs_create_u64("corrupt-filter-memcg", 0600, hwpoison_dir,
			   &hwpoison_filter_memcg);
#endif

	return 0;
}

module_init(pfn_inject_init);
module_exit(pfn_inject_exit);
MODULE_LICENSE("GPL");
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