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![Joao Martins](/assets/img/avatar_default.png)
memory_failure_dev_pagemap() at the moment assumes base pages (e.g. dax_lock_page()). For devmap with compound pages fetch the compound_head in case a tail page memory failure is being handled. Currently this is a nop, but in the advent of compound pages in dev_pagemap it allows memory_failure_dev_pagemap() to keep working. Without this fix memory-failure handling (i.e. MCEs on pmem) with device-dax configured namespaces will regress (and crash). Link: https://lkml.kernel.org/r/20211202204422.26777-2-joao.m.martins@oracle.com Reported-by: Jane Chu <jane.chu@oracle.com> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2307 lines
61 KiB
C
2307 lines
61 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2008, 2009 Intel Corporation
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* Authors: Andi Kleen, Fengguang Wu
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*
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* High level machine check handler. Handles pages reported by the
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* hardware as being corrupted usually due to a multi-bit ECC memory or cache
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* failure.
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*
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* In addition there is a "soft offline" entry point that allows stop using
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* not-yet-corrupted-by-suspicious pages without killing anything.
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*
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* Handles page cache pages in various states. The tricky part
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* here is that we can access any page asynchronously in respect to
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* other VM users, because memory failures could happen anytime and
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* anywhere. This could violate some of their assumptions. This is why
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* this code has to be extremely careful. Generally it tries to use
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* normal locking rules, as in get the standard locks, even if that means
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* the error handling takes potentially a long time.
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*
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* It can be very tempting to add handling for obscure cases here.
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* In general any code for handling new cases should only be added iff:
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* - You know how to test it.
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* - You have a test that can be added to mce-test
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* https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/
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* - The case actually shows up as a frequent (top 10) page state in
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* tools/vm/page-types when running a real workload.
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*
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* There are several operations here with exponential complexity because
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* of unsuitable VM data structures. For example the operation to map back
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* from RMAP chains to processes has to walk the complete process list and
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* has non linear complexity with the number. But since memory corruptions
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* are rare we hope to get away with this. This avoids impacting the core
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* VM.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/page-flags.h>
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#include <linux/kernel-page-flags.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/dax.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/export.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/backing-dev.h>
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#include <linux/migrate.h>
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#include <linux/suspend.h>
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#include <linux/slab.h>
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#include <linux/swapops.h>
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#include <linux/hugetlb.h>
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#include <linux/memory_hotplug.h>
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#include <linux/mm_inline.h>
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#include <linux/memremap.h>
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#include <linux/kfifo.h>
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#include <linux/ratelimit.h>
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#include <linux/page-isolation.h>
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#include <linux/pagewalk.h>
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#include <linux/shmem_fs.h>
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#include "internal.h"
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#include "ras/ras_event.h"
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int sysctl_memory_failure_early_kill __read_mostly = 0;
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int sysctl_memory_failure_recovery __read_mostly = 1;
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atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
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static bool __page_handle_poison(struct page *page)
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{
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int ret;
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zone_pcp_disable(page_zone(page));
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ret = dissolve_free_huge_page(page);
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if (!ret)
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ret = take_page_off_buddy(page);
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zone_pcp_enable(page_zone(page));
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return ret > 0;
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}
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static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
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{
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if (hugepage_or_freepage) {
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/*
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* Doing this check for free pages is also fine since dissolve_free_huge_page
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* returns 0 for non-hugetlb pages as well.
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*/
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if (!__page_handle_poison(page))
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/*
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* We could fail to take off the target page from buddy
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* for example due to racy page allocation, but that's
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* acceptable because soft-offlined page is not broken
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* and if someone really want to use it, they should
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* take it.
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*/
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return false;
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}
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SetPageHWPoison(page);
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if (release)
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put_page(page);
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page_ref_inc(page);
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num_poisoned_pages_inc();
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return true;
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}
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#if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
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u32 hwpoison_filter_enable = 0;
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u32 hwpoison_filter_dev_major = ~0U;
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u32 hwpoison_filter_dev_minor = ~0U;
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u64 hwpoison_filter_flags_mask;
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u64 hwpoison_filter_flags_value;
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EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
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EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
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EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
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EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
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EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
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static int hwpoison_filter_dev(struct page *p)
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{
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struct address_space *mapping;
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dev_t dev;
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if (hwpoison_filter_dev_major == ~0U &&
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hwpoison_filter_dev_minor == ~0U)
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return 0;
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/*
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* page_mapping() does not accept slab pages.
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*/
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if (PageSlab(p))
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return -EINVAL;
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mapping = page_mapping(p);
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if (mapping == NULL || mapping->host == NULL)
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return -EINVAL;
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dev = mapping->host->i_sb->s_dev;
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if (hwpoison_filter_dev_major != ~0U &&
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hwpoison_filter_dev_major != MAJOR(dev))
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return -EINVAL;
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if (hwpoison_filter_dev_minor != ~0U &&
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hwpoison_filter_dev_minor != MINOR(dev))
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return -EINVAL;
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return 0;
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}
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static int hwpoison_filter_flags(struct page *p)
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{
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if (!hwpoison_filter_flags_mask)
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return 0;
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if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
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hwpoison_filter_flags_value)
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return 0;
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else
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return -EINVAL;
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}
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/*
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* This allows stress tests to limit test scope to a collection of tasks
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* by putting them under some memcg. This prevents killing unrelated/important
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* processes such as /sbin/init. Note that the target task may share clean
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* pages with init (eg. libc text), which is harmless. If the target task
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* share _dirty_ pages with another task B, the test scheme must make sure B
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* is also included in the memcg. At last, due to race conditions this filter
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* can only guarantee that the page either belongs to the memcg tasks, or is
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* a freed page.
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*/
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#ifdef CONFIG_MEMCG
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u64 hwpoison_filter_memcg;
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EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
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static int hwpoison_filter_task(struct page *p)
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{
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if (!hwpoison_filter_memcg)
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return 0;
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if (page_cgroup_ino(p) != hwpoison_filter_memcg)
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return -EINVAL;
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return 0;
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}
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#else
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static int hwpoison_filter_task(struct page *p) { return 0; }
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#endif
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int hwpoison_filter(struct page *p)
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{
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if (!hwpoison_filter_enable)
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return 0;
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if (hwpoison_filter_dev(p))
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return -EINVAL;
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if (hwpoison_filter_flags(p))
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return -EINVAL;
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if (hwpoison_filter_task(p))
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return -EINVAL;
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return 0;
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}
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#else
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int hwpoison_filter(struct page *p)
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{
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return 0;
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}
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#endif
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EXPORT_SYMBOL_GPL(hwpoison_filter);
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/*
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* Kill all processes that have a poisoned page mapped and then isolate
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* the page.
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*
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* General strategy:
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* Find all processes having the page mapped and kill them.
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* But we keep a page reference around so that the page is not
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* actually freed yet.
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* Then stash the page away
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*
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* There's no convenient way to get back to mapped processes
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* from the VMAs. So do a brute-force search over all
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* running processes.
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*
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* Remember that machine checks are not common (or rather
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* if they are common you have other problems), so this shouldn't
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* be a performance issue.
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*
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* Also there are some races possible while we get from the
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* error detection to actually handle it.
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*/
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struct to_kill {
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struct list_head nd;
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struct task_struct *tsk;
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unsigned long addr;
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short size_shift;
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};
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/*
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* Send all the processes who have the page mapped a signal.
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* ``action optional'' if they are not immediately affected by the error
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* ``action required'' if error happened in current execution context
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*/
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static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
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{
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struct task_struct *t = tk->tsk;
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short addr_lsb = tk->size_shift;
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int ret = 0;
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pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
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pfn, t->comm, t->pid);
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if (flags & MF_ACTION_REQUIRED) {
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if (t == current)
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ret = force_sig_mceerr(BUS_MCEERR_AR,
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(void __user *)tk->addr, addr_lsb);
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else
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/* Signal other processes sharing the page if they have PF_MCE_EARLY set. */
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ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
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addr_lsb, t);
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} else {
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/*
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* Don't use force here, it's convenient if the signal
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* can be temporarily blocked.
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* This could cause a loop when the user sets SIGBUS
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* to SIG_IGN, but hopefully no one will do that?
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*/
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ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
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addr_lsb, t); /* synchronous? */
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}
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if (ret < 0)
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pr_info("Memory failure: Error sending signal to %s:%d: %d\n",
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t->comm, t->pid, ret);
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return ret;
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}
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/*
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* Unknown page type encountered. Try to check whether it can turn PageLRU by
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* lru_add_drain_all.
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*/
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void shake_page(struct page *p)
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{
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if (PageHuge(p))
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return;
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if (!PageSlab(p)) {
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lru_add_drain_all();
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if (PageLRU(p) || is_free_buddy_page(p))
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return;
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}
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/*
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* TODO: Could shrink slab caches here if a lightweight range-based
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* shrinker will be available.
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*/
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}
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EXPORT_SYMBOL_GPL(shake_page);
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static unsigned long dev_pagemap_mapping_shift(struct page *page,
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struct vm_area_struct *vma)
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{
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unsigned long address = vma_address(page, vma);
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unsigned long ret = 0;
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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pgd = pgd_offset(vma->vm_mm, address);
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if (!pgd_present(*pgd))
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return 0;
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p4d = p4d_offset(pgd, address);
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if (!p4d_present(*p4d))
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return 0;
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pud = pud_offset(p4d, address);
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if (!pud_present(*pud))
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return 0;
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if (pud_devmap(*pud))
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return PUD_SHIFT;
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pmd = pmd_offset(pud, address);
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if (!pmd_present(*pmd))
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return 0;
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if (pmd_devmap(*pmd))
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return PMD_SHIFT;
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pte = pte_offset_map(pmd, address);
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if (pte_present(*pte) && pte_devmap(*pte))
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ret = PAGE_SHIFT;
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pte_unmap(pte);
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return ret;
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}
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/*
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* Failure handling: if we can't find or can't kill a process there's
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* not much we can do. We just print a message and ignore otherwise.
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*/
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/*
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* Schedule a process for later kill.
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* Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
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*/
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static void add_to_kill(struct task_struct *tsk, struct page *p,
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struct vm_area_struct *vma,
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struct list_head *to_kill)
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{
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struct to_kill *tk;
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tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
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if (!tk) {
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pr_err("Memory failure: Out of memory while machine check handling\n");
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return;
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}
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tk->addr = page_address_in_vma(p, vma);
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if (is_zone_device_page(p))
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tk->size_shift = dev_pagemap_mapping_shift(p, vma);
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else
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tk->size_shift = page_shift(compound_head(p));
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/*
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* Send SIGKILL if "tk->addr == -EFAULT". Also, as
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* "tk->size_shift" is always non-zero for !is_zone_device_page(),
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* so "tk->size_shift == 0" effectively checks no mapping on
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* ZONE_DEVICE. Indeed, when a devdax page is mmapped N times
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* to a process' address space, it's possible not all N VMAs
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* contain mappings for the page, but at least one VMA does.
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* Only deliver SIGBUS with payload derived from the VMA that
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* has a mapping for the page.
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*/
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if (tk->addr == -EFAULT) {
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pr_info("Memory failure: Unable to find user space address %lx in %s\n",
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page_to_pfn(p), tsk->comm);
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} else if (tk->size_shift == 0) {
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kfree(tk);
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return;
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}
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get_task_struct(tsk);
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tk->tsk = tsk;
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list_add_tail(&tk->nd, to_kill);
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}
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/*
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* Kill the processes that have been collected earlier.
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*
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* Only do anything when FORCEKILL is set, otherwise just free the
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* list (this is used for clean pages which do not need killing)
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* Also when FAIL is set do a force kill because something went
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* wrong earlier.
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*/
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static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
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unsigned long pfn, int flags)
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{
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struct to_kill *tk, *next;
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list_for_each_entry_safe (tk, next, to_kill, nd) {
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if (forcekill) {
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/*
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* In case something went wrong with munmapping
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* make sure the process doesn't catch the
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* signal and then access the memory. Just kill it.
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*/
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if (fail || tk->addr == -EFAULT) {
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pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
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pfn, tk->tsk->comm, tk->tsk->pid);
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do_send_sig_info(SIGKILL, SEND_SIG_PRIV,
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tk->tsk, PIDTYPE_PID);
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}
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/*
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* In theory the process could have mapped
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* something else on the address in-between. We could
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* check for that, but we need to tell the
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* process anyways.
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*/
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else if (kill_proc(tk, pfn, flags) < 0)
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pr_err("Memory failure: %#lx: Cannot send advisory machine check signal to %s:%d\n",
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pfn, tk->tsk->comm, tk->tsk->pid);
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}
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put_task_struct(tk->tsk);
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kfree(tk);
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}
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}
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/*
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* Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
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* on behalf of the thread group. Return task_struct of the (first found)
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* dedicated thread if found, and return NULL otherwise.
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*
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* We already hold read_lock(&tasklist_lock) in the caller, so we don't
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* have to call rcu_read_lock/unlock() in this function.
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*/
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static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
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{
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struct task_struct *t;
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for_each_thread(tsk, t) {
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if (t->flags & PF_MCE_PROCESS) {
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if (t->flags & PF_MCE_EARLY)
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return t;
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} else {
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if (sysctl_memory_failure_early_kill)
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return t;
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}
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}
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return NULL;
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}
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/*
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* Determine whether a given process is "early kill" process which expects
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* to be signaled when some page under the process is hwpoisoned.
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* Return task_struct of the dedicated thread (main thread unless explicitly
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* specified) if the process is "early kill" and otherwise returns NULL.
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*
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* Note that the above is true for Action Optional case. For Action Required
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* case, it's only meaningful to the current thread which need to be signaled
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* with SIGBUS, this error is Action Optional for other non current
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* processes sharing the same error page,if the process is "early kill", the
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* task_struct of the dedicated thread will also be returned.
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*/
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static struct task_struct *task_early_kill(struct task_struct *tsk,
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int force_early)
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{
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if (!tsk->mm)
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return NULL;
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/*
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* Comparing ->mm here because current task might represent
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* a subthread, while tsk always points to the main thread.
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*/
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if (force_early && tsk->mm == current->mm)
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return current;
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return find_early_kill_thread(tsk);
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}
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/*
|
|
* Collect processes when the error hit an anonymous page.
|
|
*/
|
|
static void collect_procs_anon(struct page *page, struct list_head *to_kill,
|
|
int force_early)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct task_struct *tsk;
|
|
struct anon_vma *av;
|
|
pgoff_t pgoff;
|
|
|
|
av = page_lock_anon_vma_read(page);
|
|
if (av == NULL) /* Not actually mapped anymore */
|
|
return;
|
|
|
|
pgoff = page_to_pgoff(page);
|
|
read_lock(&tasklist_lock);
|
|
for_each_process (tsk) {
|
|
struct anon_vma_chain *vmac;
|
|
struct task_struct *t = task_early_kill(tsk, force_early);
|
|
|
|
if (!t)
|
|
continue;
|
|
anon_vma_interval_tree_foreach(vmac, &av->rb_root,
|
|
pgoff, pgoff) {
|
|
vma = vmac->vma;
|
|
if (!page_mapped_in_vma(page, vma))
|
|
continue;
|
|
if (vma->vm_mm == t->mm)
|
|
add_to_kill(t, page, vma, to_kill);
|
|
}
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
page_unlock_anon_vma_read(av);
|
|
}
|
|
|
|
/*
|
|
* Collect processes when the error hit a file mapped page.
|
|
*/
|
|
static void collect_procs_file(struct page *page, struct list_head *to_kill,
|
|
int force_early)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct task_struct *tsk;
|
|
struct address_space *mapping = page->mapping;
|
|
pgoff_t pgoff;
|
|
|
|
i_mmap_lock_read(mapping);
|
|
read_lock(&tasklist_lock);
|
|
pgoff = page_to_pgoff(page);
|
|
for_each_process(tsk) {
|
|
struct task_struct *t = task_early_kill(tsk, force_early);
|
|
|
|
if (!t)
|
|
continue;
|
|
vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
|
|
pgoff) {
|
|
/*
|
|
* Send early kill signal to tasks where a vma covers
|
|
* the page but the corrupted page is not necessarily
|
|
* mapped it in its pte.
|
|
* Assume applications who requested early kill want
|
|
* to be informed of all such data corruptions.
|
|
*/
|
|
if (vma->vm_mm == t->mm)
|
|
add_to_kill(t, page, vma, to_kill);
|
|
}
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
/*
|
|
* Collect the processes who have the corrupted page mapped to kill.
|
|
*/
|
|
static void collect_procs(struct page *page, struct list_head *tokill,
|
|
int force_early)
|
|
{
|
|
if (!page->mapping)
|
|
return;
|
|
|
|
if (PageAnon(page))
|
|
collect_procs_anon(page, tokill, force_early);
|
|
else
|
|
collect_procs_file(page, tokill, force_early);
|
|
}
|
|
|
|
struct hwp_walk {
|
|
struct to_kill tk;
|
|
unsigned long pfn;
|
|
int flags;
|
|
};
|
|
|
|
static void set_to_kill(struct to_kill *tk, unsigned long addr, short shift)
|
|
{
|
|
tk->addr = addr;
|
|
tk->size_shift = shift;
|
|
}
|
|
|
|
static int check_hwpoisoned_entry(pte_t pte, unsigned long addr, short shift,
|
|
unsigned long poisoned_pfn, struct to_kill *tk)
|
|
{
|
|
unsigned long pfn = 0;
|
|
|
|
if (pte_present(pte)) {
|
|
pfn = pte_pfn(pte);
|
|
} else {
|
|
swp_entry_t swp = pte_to_swp_entry(pte);
|
|
|
|
if (is_hwpoison_entry(swp))
|
|
pfn = hwpoison_entry_to_pfn(swp);
|
|
}
|
|
|
|
if (!pfn || pfn != poisoned_pfn)
|
|
return 0;
|
|
|
|
set_to_kill(tk, addr, shift);
|
|
return 1;
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
static int check_hwpoisoned_pmd_entry(pmd_t *pmdp, unsigned long addr,
|
|
struct hwp_walk *hwp)
|
|
{
|
|
pmd_t pmd = *pmdp;
|
|
unsigned long pfn;
|
|
unsigned long hwpoison_vaddr;
|
|
|
|
if (!pmd_present(pmd))
|
|
return 0;
|
|
pfn = pmd_pfn(pmd);
|
|
if (pfn <= hwp->pfn && hwp->pfn < pfn + HPAGE_PMD_NR) {
|
|
hwpoison_vaddr = addr + ((hwp->pfn - pfn) << PAGE_SHIFT);
|
|
set_to_kill(&hwp->tk, hwpoison_vaddr, PAGE_SHIFT);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
#else
|
|
static int check_hwpoisoned_pmd_entry(pmd_t *pmdp, unsigned long addr,
|
|
struct hwp_walk *hwp)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static int hwpoison_pte_range(pmd_t *pmdp, unsigned long addr,
|
|
unsigned long end, struct mm_walk *walk)
|
|
{
|
|
struct hwp_walk *hwp = (struct hwp_walk *)walk->private;
|
|
int ret = 0;
|
|
pte_t *ptep, *mapped_pte;
|
|
spinlock_t *ptl;
|
|
|
|
ptl = pmd_trans_huge_lock(pmdp, walk->vma);
|
|
if (ptl) {
|
|
ret = check_hwpoisoned_pmd_entry(pmdp, addr, hwp);
|
|
spin_unlock(ptl);
|
|
goto out;
|
|
}
|
|
|
|
if (pmd_trans_unstable(pmdp))
|
|
goto out;
|
|
|
|
mapped_pte = ptep = pte_offset_map_lock(walk->vma->vm_mm, pmdp,
|
|
addr, &ptl);
|
|
for (; addr != end; ptep++, addr += PAGE_SIZE) {
|
|
ret = check_hwpoisoned_entry(*ptep, addr, PAGE_SHIFT,
|
|
hwp->pfn, &hwp->tk);
|
|
if (ret == 1)
|
|
break;
|
|
}
|
|
pte_unmap_unlock(mapped_pte, ptl);
|
|
out:
|
|
cond_resched();
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
static int hwpoison_hugetlb_range(pte_t *ptep, unsigned long hmask,
|
|
unsigned long addr, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct hwp_walk *hwp = (struct hwp_walk *)walk->private;
|
|
pte_t pte = huge_ptep_get(ptep);
|
|
struct hstate *h = hstate_vma(walk->vma);
|
|
|
|
return check_hwpoisoned_entry(pte, addr, huge_page_shift(h),
|
|
hwp->pfn, &hwp->tk);
|
|
}
|
|
#else
|
|
#define hwpoison_hugetlb_range NULL
|
|
#endif
|
|
|
|
static const struct mm_walk_ops hwp_walk_ops = {
|
|
.pmd_entry = hwpoison_pte_range,
|
|
.hugetlb_entry = hwpoison_hugetlb_range,
|
|
};
|
|
|
|
/*
|
|
* Sends SIGBUS to the current process with error info.
|
|
*
|
|
* This function is intended to handle "Action Required" MCEs on already
|
|
* hardware poisoned pages. They could happen, for example, when
|
|
* memory_failure() failed to unmap the error page at the first call, or
|
|
* when multiple local machine checks happened on different CPUs.
|
|
*
|
|
* MCE handler currently has no easy access to the error virtual address,
|
|
* so this function walks page table to find it. The returned virtual address
|
|
* is proper in most cases, but it could be wrong when the application
|
|
* process has multiple entries mapping the error page.
|
|
*/
|
|
static int kill_accessing_process(struct task_struct *p, unsigned long pfn,
|
|
int flags)
|
|
{
|
|
int ret;
|
|
struct hwp_walk priv = {
|
|
.pfn = pfn,
|
|
};
|
|
priv.tk.tsk = p;
|
|
|
|
mmap_read_lock(p->mm);
|
|
ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwp_walk_ops,
|
|
(void *)&priv);
|
|
if (ret == 1 && priv.tk.addr)
|
|
kill_proc(&priv.tk, pfn, flags);
|
|
mmap_read_unlock(p->mm);
|
|
return ret ? -EFAULT : -EHWPOISON;
|
|
}
|
|
|
|
static const char *action_name[] = {
|
|
[MF_IGNORED] = "Ignored",
|
|
[MF_FAILED] = "Failed",
|
|
[MF_DELAYED] = "Delayed",
|
|
[MF_RECOVERED] = "Recovered",
|
|
};
|
|
|
|
static const char * const action_page_types[] = {
|
|
[MF_MSG_KERNEL] = "reserved kernel page",
|
|
[MF_MSG_KERNEL_HIGH_ORDER] = "high-order kernel page",
|
|
[MF_MSG_SLAB] = "kernel slab page",
|
|
[MF_MSG_DIFFERENT_COMPOUND] = "different compound page after locking",
|
|
[MF_MSG_HUGE] = "huge page",
|
|
[MF_MSG_FREE_HUGE] = "free huge page",
|
|
[MF_MSG_NON_PMD_HUGE] = "non-pmd-sized huge page",
|
|
[MF_MSG_UNMAP_FAILED] = "unmapping failed page",
|
|
[MF_MSG_DIRTY_SWAPCACHE] = "dirty swapcache page",
|
|
[MF_MSG_CLEAN_SWAPCACHE] = "clean swapcache page",
|
|
[MF_MSG_DIRTY_MLOCKED_LRU] = "dirty mlocked LRU page",
|
|
[MF_MSG_CLEAN_MLOCKED_LRU] = "clean mlocked LRU page",
|
|
[MF_MSG_DIRTY_UNEVICTABLE_LRU] = "dirty unevictable LRU page",
|
|
[MF_MSG_CLEAN_UNEVICTABLE_LRU] = "clean unevictable LRU page",
|
|
[MF_MSG_DIRTY_LRU] = "dirty LRU page",
|
|
[MF_MSG_CLEAN_LRU] = "clean LRU page",
|
|
[MF_MSG_TRUNCATED_LRU] = "already truncated LRU page",
|
|
[MF_MSG_BUDDY] = "free buddy page",
|
|
[MF_MSG_DAX] = "dax page",
|
|
[MF_MSG_UNSPLIT_THP] = "unsplit thp",
|
|
[MF_MSG_UNKNOWN] = "unknown page",
|
|
};
|
|
|
|
/*
|
|
* XXX: It is possible that a page is isolated from LRU cache,
|
|
* and then kept in swap cache or failed to remove from page cache.
|
|
* The page count will stop it from being freed by unpoison.
|
|
* Stress tests should be aware of this memory leak problem.
|
|
*/
|
|
static int delete_from_lru_cache(struct page *p)
|
|
{
|
|
if (!isolate_lru_page(p)) {
|
|
/*
|
|
* Clear sensible page flags, so that the buddy system won't
|
|
* complain when the page is unpoison-and-freed.
|
|
*/
|
|
ClearPageActive(p);
|
|
ClearPageUnevictable(p);
|
|
|
|
/*
|
|
* Poisoned page might never drop its ref count to 0 so we have
|
|
* to uncharge it manually from its memcg.
|
|
*/
|
|
mem_cgroup_uncharge(page_folio(p));
|
|
|
|
/*
|
|
* drop the page count elevated by isolate_lru_page()
|
|
*/
|
|
put_page(p);
|
|
return 0;
|
|
}
|
|
return -EIO;
|
|
}
|
|
|
|
static int truncate_error_page(struct page *p, unsigned long pfn,
|
|
struct address_space *mapping)
|
|
{
|
|
int ret = MF_FAILED;
|
|
|
|
if (mapping->a_ops->error_remove_page) {
|
|
int err = mapping->a_ops->error_remove_page(mapping, p);
|
|
|
|
if (err != 0) {
|
|
pr_info("Memory failure: %#lx: Failed to punch page: %d\n",
|
|
pfn, err);
|
|
} else if (page_has_private(p) &&
|
|
!try_to_release_page(p, GFP_NOIO)) {
|
|
pr_info("Memory failure: %#lx: failed to release buffers\n",
|
|
pfn);
|
|
} else {
|
|
ret = MF_RECOVERED;
|
|
}
|
|
} else {
|
|
/*
|
|
* If the file system doesn't support it just invalidate
|
|
* This fails on dirty or anything with private pages
|
|
*/
|
|
if (invalidate_inode_page(p))
|
|
ret = MF_RECOVERED;
|
|
else
|
|
pr_info("Memory failure: %#lx: Failed to invalidate\n",
|
|
pfn);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
struct page_state {
|
|
unsigned long mask;
|
|
unsigned long res;
|
|
enum mf_action_page_type type;
|
|
|
|
/* Callback ->action() has to unlock the relevant page inside it. */
|
|
int (*action)(struct page_state *ps, struct page *p);
|
|
};
|
|
|
|
/*
|
|
* Return true if page is still referenced by others, otherwise return
|
|
* false.
|
|
*
|
|
* The extra_pins is true when one extra refcount is expected.
|
|
*/
|
|
static bool has_extra_refcount(struct page_state *ps, struct page *p,
|
|
bool extra_pins)
|
|
{
|
|
int count = page_count(p) - 1;
|
|
|
|
if (extra_pins)
|
|
count -= 1;
|
|
|
|
if (count > 0) {
|
|
pr_err("Memory failure: %#lx: %s still referenced by %d users\n",
|
|
page_to_pfn(p), action_page_types[ps->type], count);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Error hit kernel page.
|
|
* Do nothing, try to be lucky and not touch this instead. For a few cases we
|
|
* could be more sophisticated.
|
|
*/
|
|
static int me_kernel(struct page_state *ps, struct page *p)
|
|
{
|
|
unlock_page(p);
|
|
return MF_IGNORED;
|
|
}
|
|
|
|
/*
|
|
* Page in unknown state. Do nothing.
|
|
*/
|
|
static int me_unknown(struct page_state *ps, struct page *p)
|
|
{
|
|
pr_err("Memory failure: %#lx: Unknown page state\n", page_to_pfn(p));
|
|
unlock_page(p);
|
|
return MF_FAILED;
|
|
}
|
|
|
|
/*
|
|
* Clean (or cleaned) page cache page.
|
|
*/
|
|
static int me_pagecache_clean(struct page_state *ps, struct page *p)
|
|
{
|
|
int ret;
|
|
struct address_space *mapping;
|
|
bool extra_pins;
|
|
|
|
delete_from_lru_cache(p);
|
|
|
|
/*
|
|
* For anonymous pages we're done the only reference left
|
|
* should be the one m_f() holds.
|
|
*/
|
|
if (PageAnon(p)) {
|
|
ret = MF_RECOVERED;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Now truncate the page in the page cache. This is really
|
|
* more like a "temporary hole punch"
|
|
* Don't do this for block devices when someone else
|
|
* has a reference, because it could be file system metadata
|
|
* and that's not safe to truncate.
|
|
*/
|
|
mapping = page_mapping(p);
|
|
if (!mapping) {
|
|
/*
|
|
* Page has been teared down in the meanwhile
|
|
*/
|
|
ret = MF_FAILED;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* The shmem page is kept in page cache instead of truncating
|
|
* so is expected to have an extra refcount after error-handling.
|
|
*/
|
|
extra_pins = shmem_mapping(mapping);
|
|
|
|
/*
|
|
* Truncation is a bit tricky. Enable it per file system for now.
|
|
*
|
|
* Open: to take i_rwsem or not for this? Right now we don't.
|
|
*/
|
|
ret = truncate_error_page(p, page_to_pfn(p), mapping);
|
|
if (has_extra_refcount(ps, p, extra_pins))
|
|
ret = MF_FAILED;
|
|
|
|
out:
|
|
unlock_page(p);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Dirty pagecache page
|
|
* Issues: when the error hit a hole page the error is not properly
|
|
* propagated.
|
|
*/
|
|
static int me_pagecache_dirty(struct page_state *ps, struct page *p)
|
|
{
|
|
struct address_space *mapping = page_mapping(p);
|
|
|
|
SetPageError(p);
|
|
/* TBD: print more information about the file. */
|
|
if (mapping) {
|
|
/*
|
|
* IO error will be reported by write(), fsync(), etc.
|
|
* who check the mapping.
|
|
* This way the application knows that something went
|
|
* wrong with its dirty file data.
|
|
*
|
|
* There's one open issue:
|
|
*
|
|
* The EIO will be only reported on the next IO
|
|
* operation and then cleared through the IO map.
|
|
* Normally Linux has two mechanisms to pass IO error
|
|
* first through the AS_EIO flag in the address space
|
|
* and then through the PageError flag in the page.
|
|
* Since we drop pages on memory failure handling the
|
|
* only mechanism open to use is through AS_AIO.
|
|
*
|
|
* This has the disadvantage that it gets cleared on
|
|
* the first operation that returns an error, while
|
|
* the PageError bit is more sticky and only cleared
|
|
* when the page is reread or dropped. If an
|
|
* application assumes it will always get error on
|
|
* fsync, but does other operations on the fd before
|
|
* and the page is dropped between then the error
|
|
* will not be properly reported.
|
|
*
|
|
* This can already happen even without hwpoisoned
|
|
* pages: first on metadata IO errors (which only
|
|
* report through AS_EIO) or when the page is dropped
|
|
* at the wrong time.
|
|
*
|
|
* So right now we assume that the application DTRT on
|
|
* the first EIO, but we're not worse than other parts
|
|
* of the kernel.
|
|
*/
|
|
mapping_set_error(mapping, -EIO);
|
|
}
|
|
|
|
return me_pagecache_clean(ps, p);
|
|
}
|
|
|
|
/*
|
|
* Clean and dirty swap cache.
|
|
*
|
|
* Dirty swap cache page is tricky to handle. The page could live both in page
|
|
* cache and swap cache(ie. page is freshly swapped in). So it could be
|
|
* referenced concurrently by 2 types of PTEs:
|
|
* normal PTEs and swap PTEs. We try to handle them consistently by calling
|
|
* try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
|
|
* and then
|
|
* - clear dirty bit to prevent IO
|
|
* - remove from LRU
|
|
* - but keep in the swap cache, so that when we return to it on
|
|
* a later page fault, we know the application is accessing
|
|
* corrupted data and shall be killed (we installed simple
|
|
* interception code in do_swap_page to catch it).
|
|
*
|
|
* Clean swap cache pages can be directly isolated. A later page fault will
|
|
* bring in the known good data from disk.
|
|
*/
|
|
static int me_swapcache_dirty(struct page_state *ps, struct page *p)
|
|
{
|
|
int ret;
|
|
bool extra_pins = false;
|
|
|
|
ClearPageDirty(p);
|
|
/* Trigger EIO in shmem: */
|
|
ClearPageUptodate(p);
|
|
|
|
ret = delete_from_lru_cache(p) ? MF_FAILED : MF_DELAYED;
|
|
unlock_page(p);
|
|
|
|
if (ret == MF_DELAYED)
|
|
extra_pins = true;
|
|
|
|
if (has_extra_refcount(ps, p, extra_pins))
|
|
ret = MF_FAILED;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int me_swapcache_clean(struct page_state *ps, struct page *p)
|
|
{
|
|
int ret;
|
|
|
|
delete_from_swap_cache(p);
|
|
|
|
ret = delete_from_lru_cache(p) ? MF_FAILED : MF_RECOVERED;
|
|
unlock_page(p);
|
|
|
|
if (has_extra_refcount(ps, p, false))
|
|
ret = MF_FAILED;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Huge pages. Needs work.
|
|
* Issues:
|
|
* - Error on hugepage is contained in hugepage unit (not in raw page unit.)
|
|
* To narrow down kill region to one page, we need to break up pmd.
|
|
*/
|
|
static int me_huge_page(struct page_state *ps, struct page *p)
|
|
{
|
|
int res;
|
|
struct page *hpage = compound_head(p);
|
|
struct address_space *mapping;
|
|
|
|
if (!PageHuge(hpage))
|
|
return MF_DELAYED;
|
|
|
|
mapping = page_mapping(hpage);
|
|
if (mapping) {
|
|
res = truncate_error_page(hpage, page_to_pfn(p), mapping);
|
|
unlock_page(hpage);
|
|
} else {
|
|
res = MF_FAILED;
|
|
unlock_page(hpage);
|
|
/*
|
|
* migration entry prevents later access on error anonymous
|
|
* hugepage, so we can free and dissolve it into buddy to
|
|
* save healthy subpages.
|
|
*/
|
|
if (PageAnon(hpage))
|
|
put_page(hpage);
|
|
if (__page_handle_poison(p)) {
|
|
page_ref_inc(p);
|
|
res = MF_RECOVERED;
|
|
}
|
|
}
|
|
|
|
if (has_extra_refcount(ps, p, false))
|
|
res = MF_FAILED;
|
|
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Various page states we can handle.
|
|
*
|
|
* A page state is defined by its current page->flags bits.
|
|
* The table matches them in order and calls the right handler.
|
|
*
|
|
* This is quite tricky because we can access page at any time
|
|
* in its live cycle, so all accesses have to be extremely careful.
|
|
*
|
|
* This is not complete. More states could be added.
|
|
* For any missing state don't attempt recovery.
|
|
*/
|
|
|
|
#define dirty (1UL << PG_dirty)
|
|
#define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked))
|
|
#define unevict (1UL << PG_unevictable)
|
|
#define mlock (1UL << PG_mlocked)
|
|
#define lru (1UL << PG_lru)
|
|
#define head (1UL << PG_head)
|
|
#define slab (1UL << PG_slab)
|
|
#define reserved (1UL << PG_reserved)
|
|
|
|
static struct page_state error_states[] = {
|
|
{ reserved, reserved, MF_MSG_KERNEL, me_kernel },
|
|
/*
|
|
* free pages are specially detected outside this table:
|
|
* PG_buddy pages only make a small fraction of all free pages.
|
|
*/
|
|
|
|
/*
|
|
* Could in theory check if slab page is free or if we can drop
|
|
* currently unused objects without touching them. But just
|
|
* treat it as standard kernel for now.
|
|
*/
|
|
{ slab, slab, MF_MSG_SLAB, me_kernel },
|
|
|
|
{ head, head, MF_MSG_HUGE, me_huge_page },
|
|
|
|
{ sc|dirty, sc|dirty, MF_MSG_DIRTY_SWAPCACHE, me_swapcache_dirty },
|
|
{ sc|dirty, sc, MF_MSG_CLEAN_SWAPCACHE, me_swapcache_clean },
|
|
|
|
{ mlock|dirty, mlock|dirty, MF_MSG_DIRTY_MLOCKED_LRU, me_pagecache_dirty },
|
|
{ mlock|dirty, mlock, MF_MSG_CLEAN_MLOCKED_LRU, me_pagecache_clean },
|
|
|
|
{ unevict|dirty, unevict|dirty, MF_MSG_DIRTY_UNEVICTABLE_LRU, me_pagecache_dirty },
|
|
{ unevict|dirty, unevict, MF_MSG_CLEAN_UNEVICTABLE_LRU, me_pagecache_clean },
|
|
|
|
{ lru|dirty, lru|dirty, MF_MSG_DIRTY_LRU, me_pagecache_dirty },
|
|
{ lru|dirty, lru, MF_MSG_CLEAN_LRU, me_pagecache_clean },
|
|
|
|
/*
|
|
* Catchall entry: must be at end.
|
|
*/
|
|
{ 0, 0, MF_MSG_UNKNOWN, me_unknown },
|
|
};
|
|
|
|
#undef dirty
|
|
#undef sc
|
|
#undef unevict
|
|
#undef mlock
|
|
#undef lru
|
|
#undef head
|
|
#undef slab
|
|
#undef reserved
|
|
|
|
/*
|
|
* "Dirty/Clean" indication is not 100% accurate due to the possibility of
|
|
* setting PG_dirty outside page lock. See also comment above set_page_dirty().
|
|
*/
|
|
static void action_result(unsigned long pfn, enum mf_action_page_type type,
|
|
enum mf_result result)
|
|
{
|
|
trace_memory_failure_event(pfn, type, result);
|
|
|
|
pr_err("Memory failure: %#lx: recovery action for %s: %s\n",
|
|
pfn, action_page_types[type], action_name[result]);
|
|
}
|
|
|
|
static int page_action(struct page_state *ps, struct page *p,
|
|
unsigned long pfn)
|
|
{
|
|
int result;
|
|
|
|
/* page p should be unlocked after returning from ps->action(). */
|
|
result = ps->action(ps, p);
|
|
|
|
action_result(pfn, ps->type, result);
|
|
|
|
/* Could do more checks here if page looks ok */
|
|
/*
|
|
* Could adjust zone counters here to correct for the missing page.
|
|
*/
|
|
|
|
return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
|
|
}
|
|
|
|
static inline bool PageHWPoisonTakenOff(struct page *page)
|
|
{
|
|
return PageHWPoison(page) && page_private(page) == MAGIC_HWPOISON;
|
|
}
|
|
|
|
void SetPageHWPoisonTakenOff(struct page *page)
|
|
{
|
|
set_page_private(page, MAGIC_HWPOISON);
|
|
}
|
|
|
|
void ClearPageHWPoisonTakenOff(struct page *page)
|
|
{
|
|
if (PageHWPoison(page))
|
|
set_page_private(page, 0);
|
|
}
|
|
|
|
/*
|
|
* Return true if a page type of a given page is supported by hwpoison
|
|
* mechanism (while handling could fail), otherwise false. This function
|
|
* does not return true for hugetlb or device memory pages, so it's assumed
|
|
* to be called only in the context where we never have such pages.
|
|
*/
|
|
static inline bool HWPoisonHandlable(struct page *page)
|
|
{
|
|
return PageLRU(page) || __PageMovable(page) || is_free_buddy_page(page);
|
|
}
|
|
|
|
static int __get_hwpoison_page(struct page *page)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
int ret = 0;
|
|
bool hugetlb = false;
|
|
|
|
ret = get_hwpoison_huge_page(head, &hugetlb);
|
|
if (hugetlb)
|
|
return ret;
|
|
|
|
/*
|
|
* This check prevents from calling get_hwpoison_unless_zero()
|
|
* for any unsupported type of page in order to reduce the risk of
|
|
* unexpected races caused by taking a page refcount.
|
|
*/
|
|
if (!HWPoisonHandlable(head))
|
|
return -EBUSY;
|
|
|
|
if (get_page_unless_zero(head)) {
|
|
if (head == compound_head(page))
|
|
return 1;
|
|
|
|
pr_info("Memory failure: %#lx cannot catch tail\n",
|
|
page_to_pfn(page));
|
|
put_page(head);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int get_any_page(struct page *p, unsigned long flags)
|
|
{
|
|
int ret = 0, pass = 0;
|
|
bool count_increased = false;
|
|
|
|
if (flags & MF_COUNT_INCREASED)
|
|
count_increased = true;
|
|
|
|
try_again:
|
|
if (!count_increased) {
|
|
ret = __get_hwpoison_page(p);
|
|
if (!ret) {
|
|
if (page_count(p)) {
|
|
/* We raced with an allocation, retry. */
|
|
if (pass++ < 3)
|
|
goto try_again;
|
|
ret = -EBUSY;
|
|
} else if (!PageHuge(p) && !is_free_buddy_page(p)) {
|
|
/* We raced with put_page, retry. */
|
|
if (pass++ < 3)
|
|
goto try_again;
|
|
ret = -EIO;
|
|
}
|
|
goto out;
|
|
} else if (ret == -EBUSY) {
|
|
/*
|
|
* We raced with (possibly temporary) unhandlable
|
|
* page, retry.
|
|
*/
|
|
if (pass++ < 3) {
|
|
shake_page(p);
|
|
goto try_again;
|
|
}
|
|
ret = -EIO;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
if (PageHuge(p) || HWPoisonHandlable(p)) {
|
|
ret = 1;
|
|
} else {
|
|
/*
|
|
* A page we cannot handle. Check whether we can turn
|
|
* it into something we can handle.
|
|
*/
|
|
if (pass++ < 3) {
|
|
put_page(p);
|
|
shake_page(p);
|
|
count_increased = false;
|
|
goto try_again;
|
|
}
|
|
put_page(p);
|
|
ret = -EIO;
|
|
}
|
|
out:
|
|
if (ret == -EIO)
|
|
dump_page(p, "hwpoison: unhandlable page");
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int __get_unpoison_page(struct page *page)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
int ret = 0;
|
|
bool hugetlb = false;
|
|
|
|
ret = get_hwpoison_huge_page(head, &hugetlb);
|
|
if (hugetlb)
|
|
return ret;
|
|
|
|
/*
|
|
* PageHWPoisonTakenOff pages are not only marked as PG_hwpoison,
|
|
* but also isolated from buddy freelist, so need to identify the
|
|
* state and have to cancel both operations to unpoison.
|
|
*/
|
|
if (PageHWPoisonTakenOff(page))
|
|
return -EHWPOISON;
|
|
|
|
return get_page_unless_zero(page) ? 1 : 0;
|
|
}
|
|
|
|
/**
|
|
* get_hwpoison_page() - Get refcount for memory error handling
|
|
* @p: Raw error page (hit by memory error)
|
|
* @flags: Flags controlling behavior of error handling
|
|
*
|
|
* get_hwpoison_page() takes a page refcount of an error page to handle memory
|
|
* error on it, after checking that the error page is in a well-defined state
|
|
* (defined as a page-type we can successfully handle the memory error on it,
|
|
* such as LRU page and hugetlb page).
|
|
*
|
|
* Memory error handling could be triggered at any time on any type of page,
|
|
* so it's prone to race with typical memory management lifecycle (like
|
|
* allocation and free). So to avoid such races, get_hwpoison_page() takes
|
|
* extra care for the error page's state (as done in __get_hwpoison_page()),
|
|
* and has some retry logic in get_any_page().
|
|
*
|
|
* When called from unpoison_memory(), the caller should already ensure that
|
|
* the given page has PG_hwpoison. So it's never reused for other page
|
|
* allocations, and __get_unpoison_page() never races with them.
|
|
*
|
|
* Return: 0 on failure,
|
|
* 1 on success for in-use pages in a well-defined state,
|
|
* -EIO for pages on which we can not handle memory errors,
|
|
* -EBUSY when get_hwpoison_page() has raced with page lifecycle
|
|
* operations like allocation and free,
|
|
* -EHWPOISON when the page is hwpoisoned and taken off from buddy.
|
|
*/
|
|
static int get_hwpoison_page(struct page *p, unsigned long flags)
|
|
{
|
|
int ret;
|
|
|
|
zone_pcp_disable(page_zone(p));
|
|
if (flags & MF_UNPOISON)
|
|
ret = __get_unpoison_page(p);
|
|
else
|
|
ret = get_any_page(p, flags);
|
|
zone_pcp_enable(page_zone(p));
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Do all that is necessary to remove user space mappings. Unmap
|
|
* the pages and send SIGBUS to the processes if the data was dirty.
|
|
*/
|
|
static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
|
|
int flags, struct page *hpage)
|
|
{
|
|
enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC;
|
|
struct address_space *mapping;
|
|
LIST_HEAD(tokill);
|
|
bool unmap_success;
|
|
int kill = 1, forcekill;
|
|
bool mlocked = PageMlocked(hpage);
|
|
|
|
/*
|
|
* Here we are interested only in user-mapped pages, so skip any
|
|
* other types of pages.
|
|
*/
|
|
if (PageReserved(p) || PageSlab(p))
|
|
return true;
|
|
if (!(PageLRU(hpage) || PageHuge(p)))
|
|
return true;
|
|
|
|
/*
|
|
* This check implies we don't kill processes if their pages
|
|
* are in the swap cache early. Those are always late kills.
|
|
*/
|
|
if (!page_mapped(hpage))
|
|
return true;
|
|
|
|
if (PageKsm(p)) {
|
|
pr_err("Memory failure: %#lx: can't handle KSM pages.\n", pfn);
|
|
return false;
|
|
}
|
|
|
|
if (PageSwapCache(p)) {
|
|
pr_err("Memory failure: %#lx: keeping poisoned page in swap cache\n",
|
|
pfn);
|
|
ttu |= TTU_IGNORE_HWPOISON;
|
|
}
|
|
|
|
/*
|
|
* Propagate the dirty bit from PTEs to struct page first, because we
|
|
* need this to decide if we should kill or just drop the page.
|
|
* XXX: the dirty test could be racy: set_page_dirty() may not always
|
|
* be called inside page lock (it's recommended but not enforced).
|
|
*/
|
|
mapping = page_mapping(hpage);
|
|
if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
|
|
mapping_can_writeback(mapping)) {
|
|
if (page_mkclean(hpage)) {
|
|
SetPageDirty(hpage);
|
|
} else {
|
|
kill = 0;
|
|
ttu |= TTU_IGNORE_HWPOISON;
|
|
pr_info("Memory failure: %#lx: corrupted page was clean: dropped without side effects\n",
|
|
pfn);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* First collect all the processes that have the page
|
|
* mapped in dirty form. This has to be done before try_to_unmap,
|
|
* because ttu takes the rmap data structures down.
|
|
*
|
|
* Error handling: We ignore errors here because
|
|
* there's nothing that can be done.
|
|
*/
|
|
if (kill)
|
|
collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
|
|
|
|
if (!PageHuge(hpage)) {
|
|
try_to_unmap(hpage, ttu);
|
|
} else {
|
|
if (!PageAnon(hpage)) {
|
|
/*
|
|
* For hugetlb pages in shared mappings, try_to_unmap
|
|
* could potentially call huge_pmd_unshare. Because of
|
|
* this, take semaphore in write mode here and set
|
|
* TTU_RMAP_LOCKED to indicate we have taken the lock
|
|
* at this higher level.
|
|
*/
|
|
mapping = hugetlb_page_mapping_lock_write(hpage);
|
|
if (mapping) {
|
|
try_to_unmap(hpage, ttu|TTU_RMAP_LOCKED);
|
|
i_mmap_unlock_write(mapping);
|
|
} else
|
|
pr_info("Memory failure: %#lx: could not lock mapping for mapped huge page\n", pfn);
|
|
} else {
|
|
try_to_unmap(hpage, ttu);
|
|
}
|
|
}
|
|
|
|
unmap_success = !page_mapped(hpage);
|
|
if (!unmap_success)
|
|
pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n",
|
|
pfn, page_mapcount(hpage));
|
|
|
|
/*
|
|
* try_to_unmap() might put mlocked page in lru cache, so call
|
|
* shake_page() again to ensure that it's flushed.
|
|
*/
|
|
if (mlocked)
|
|
shake_page(hpage);
|
|
|
|
/*
|
|
* Now that the dirty bit has been propagated to the
|
|
* struct page and all unmaps done we can decide if
|
|
* killing is needed or not. Only kill when the page
|
|
* was dirty or the process is not restartable,
|
|
* otherwise the tokill list is merely
|
|
* freed. When there was a problem unmapping earlier
|
|
* use a more force-full uncatchable kill to prevent
|
|
* any accesses to the poisoned memory.
|
|
*/
|
|
forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
|
|
kill_procs(&tokill, forcekill, !unmap_success, pfn, flags);
|
|
|
|
return unmap_success;
|
|
}
|
|
|
|
static int identify_page_state(unsigned long pfn, struct page *p,
|
|
unsigned long page_flags)
|
|
{
|
|
struct page_state *ps;
|
|
|
|
/*
|
|
* The first check uses the current page flags which may not have any
|
|
* relevant information. The second check with the saved page flags is
|
|
* carried out only if the first check can't determine the page status.
|
|
*/
|
|
for (ps = error_states;; ps++)
|
|
if ((p->flags & ps->mask) == ps->res)
|
|
break;
|
|
|
|
page_flags |= (p->flags & (1UL << PG_dirty));
|
|
|
|
if (!ps->mask)
|
|
for (ps = error_states;; ps++)
|
|
if ((page_flags & ps->mask) == ps->res)
|
|
break;
|
|
return page_action(ps, p, pfn);
|
|
}
|
|
|
|
static int try_to_split_thp_page(struct page *page, const char *msg)
|
|
{
|
|
lock_page(page);
|
|
if (unlikely(split_huge_page(page))) {
|
|
unsigned long pfn = page_to_pfn(page);
|
|
|
|
unlock_page(page);
|
|
pr_info("%s: %#lx: thp split failed\n", msg, pfn);
|
|
put_page(page);
|
|
return -EBUSY;
|
|
}
|
|
unlock_page(page);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int memory_failure_hugetlb(unsigned long pfn, int flags)
|
|
{
|
|
struct page *p = pfn_to_page(pfn);
|
|
struct page *head = compound_head(p);
|
|
int res;
|
|
unsigned long page_flags;
|
|
|
|
if (TestSetPageHWPoison(head)) {
|
|
pr_err("Memory failure: %#lx: already hardware poisoned\n",
|
|
pfn);
|
|
res = -EHWPOISON;
|
|
if (flags & MF_ACTION_REQUIRED)
|
|
res = kill_accessing_process(current, page_to_pfn(head), flags);
|
|
return res;
|
|
}
|
|
|
|
num_poisoned_pages_inc();
|
|
|
|
if (!(flags & MF_COUNT_INCREASED)) {
|
|
res = get_hwpoison_page(p, flags);
|
|
if (!res) {
|
|
lock_page(head);
|
|
if (hwpoison_filter(p)) {
|
|
if (TestClearPageHWPoison(head))
|
|
num_poisoned_pages_dec();
|
|
unlock_page(head);
|
|
return 0;
|
|
}
|
|
unlock_page(head);
|
|
res = MF_FAILED;
|
|
if (__page_handle_poison(p)) {
|
|
page_ref_inc(p);
|
|
res = MF_RECOVERED;
|
|
}
|
|
action_result(pfn, MF_MSG_FREE_HUGE, res);
|
|
return res == MF_RECOVERED ? 0 : -EBUSY;
|
|
} else if (res < 0) {
|
|
action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
lock_page(head);
|
|
page_flags = head->flags;
|
|
|
|
/*
|
|
* TODO: hwpoison for pud-sized hugetlb doesn't work right now, so
|
|
* simply disable it. In order to make it work properly, we need
|
|
* make sure that:
|
|
* - conversion of a pud that maps an error hugetlb into hwpoison
|
|
* entry properly works, and
|
|
* - other mm code walking over page table is aware of pud-aligned
|
|
* hwpoison entries.
|
|
*/
|
|
if (huge_page_size(page_hstate(head)) > PMD_SIZE) {
|
|
action_result(pfn, MF_MSG_NON_PMD_HUGE, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
if (!hwpoison_user_mappings(p, pfn, flags, head)) {
|
|
action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
return identify_page_state(pfn, p, page_flags);
|
|
out:
|
|
unlock_page(head);
|
|
return res;
|
|
}
|
|
|
|
static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
|
|
struct dev_pagemap *pgmap)
|
|
{
|
|
struct page *page = pfn_to_page(pfn);
|
|
unsigned long size = 0;
|
|
struct to_kill *tk;
|
|
LIST_HEAD(tokill);
|
|
int rc = -EBUSY;
|
|
loff_t start;
|
|
dax_entry_t cookie;
|
|
|
|
if (flags & MF_COUNT_INCREASED)
|
|
/*
|
|
* Drop the extra refcount in case we come from madvise().
|
|
*/
|
|
put_page(page);
|
|
|
|
/* device metadata space is not recoverable */
|
|
if (!pgmap_pfn_valid(pgmap, pfn)) {
|
|
rc = -ENXIO;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Pages instantiated by device-dax (not filesystem-dax)
|
|
* may be compound pages.
|
|
*/
|
|
page = compound_head(page);
|
|
|
|
/*
|
|
* Prevent the inode from being freed while we are interrogating
|
|
* the address_space, typically this would be handled by
|
|
* lock_page(), but dax pages do not use the page lock. This
|
|
* also prevents changes to the mapping of this pfn until
|
|
* poison signaling is complete.
|
|
*/
|
|
cookie = dax_lock_page(page);
|
|
if (!cookie)
|
|
goto out;
|
|
|
|
if (hwpoison_filter(page)) {
|
|
rc = 0;
|
|
goto unlock;
|
|
}
|
|
|
|
if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
|
|
/*
|
|
* TODO: Handle HMM pages which may need coordination
|
|
* with device-side memory.
|
|
*/
|
|
goto unlock;
|
|
}
|
|
|
|
/*
|
|
* Use this flag as an indication that the dax page has been
|
|
* remapped UC to prevent speculative consumption of poison.
|
|
*/
|
|
SetPageHWPoison(page);
|
|
|
|
/*
|
|
* Unlike System-RAM there is no possibility to swap in a
|
|
* different physical page at a given virtual address, so all
|
|
* userspace consumption of ZONE_DEVICE memory necessitates
|
|
* SIGBUS (i.e. MF_MUST_KILL)
|
|
*/
|
|
flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
|
|
collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED);
|
|
|
|
list_for_each_entry(tk, &tokill, nd)
|
|
if (tk->size_shift)
|
|
size = max(size, 1UL << tk->size_shift);
|
|
if (size) {
|
|
/*
|
|
* Unmap the largest mapping to avoid breaking up
|
|
* device-dax mappings which are constant size. The
|
|
* actual size of the mapping being torn down is
|
|
* communicated in siginfo, see kill_proc()
|
|
*/
|
|
start = (page->index << PAGE_SHIFT) & ~(size - 1);
|
|
unmap_mapping_range(page->mapping, start, size, 0);
|
|
}
|
|
kill_procs(&tokill, flags & MF_MUST_KILL, false, pfn, flags);
|
|
rc = 0;
|
|
unlock:
|
|
dax_unlock_page(page, cookie);
|
|
out:
|
|
/* drop pgmap ref acquired in caller */
|
|
put_dev_pagemap(pgmap);
|
|
action_result(pfn, MF_MSG_DAX, rc ? MF_FAILED : MF_RECOVERED);
|
|
return rc;
|
|
}
|
|
|
|
static DEFINE_MUTEX(mf_mutex);
|
|
|
|
/**
|
|
* memory_failure - Handle memory failure of a page.
|
|
* @pfn: Page Number of the corrupted page
|
|
* @flags: fine tune action taken
|
|
*
|
|
* This function is called by the low level machine check code
|
|
* of an architecture when it detects hardware memory corruption
|
|
* of a page. It tries its best to recover, which includes
|
|
* dropping pages, killing processes etc.
|
|
*
|
|
* The function is primarily of use for corruptions that
|
|
* happen outside the current execution context (e.g. when
|
|
* detected by a background scrubber)
|
|
*
|
|
* Must run in process context (e.g. a work queue) with interrupts
|
|
* enabled and no spinlocks hold.
|
|
*/
|
|
int memory_failure(unsigned long pfn, int flags)
|
|
{
|
|
struct page *p;
|
|
struct page *hpage;
|
|
struct page *orig_head;
|
|
struct dev_pagemap *pgmap;
|
|
int res = 0;
|
|
unsigned long page_flags;
|
|
bool retry = true;
|
|
|
|
if (!sysctl_memory_failure_recovery)
|
|
panic("Memory failure on page %lx", pfn);
|
|
|
|
mutex_lock(&mf_mutex);
|
|
|
|
p = pfn_to_online_page(pfn);
|
|
if (!p) {
|
|
res = arch_memory_failure(pfn, flags);
|
|
if (res == 0)
|
|
goto unlock_mutex;
|
|
|
|
if (pfn_valid(pfn)) {
|
|
pgmap = get_dev_pagemap(pfn, NULL);
|
|
if (pgmap) {
|
|
res = memory_failure_dev_pagemap(pfn, flags,
|
|
pgmap);
|
|
goto unlock_mutex;
|
|
}
|
|
}
|
|
pr_err("Memory failure: %#lx: memory outside kernel control\n",
|
|
pfn);
|
|
res = -ENXIO;
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
try_again:
|
|
if (PageHuge(p)) {
|
|
res = memory_failure_hugetlb(pfn, flags);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
if (TestSetPageHWPoison(p)) {
|
|
pr_err("Memory failure: %#lx: already hardware poisoned\n",
|
|
pfn);
|
|
res = -EHWPOISON;
|
|
if (flags & MF_ACTION_REQUIRED)
|
|
res = kill_accessing_process(current, pfn, flags);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
orig_head = hpage = compound_head(p);
|
|
num_poisoned_pages_inc();
|
|
|
|
/*
|
|
* We need/can do nothing about count=0 pages.
|
|
* 1) it's a free page, and therefore in safe hand:
|
|
* prep_new_page() will be the gate keeper.
|
|
* 2) it's part of a non-compound high order page.
|
|
* Implies some kernel user: cannot stop them from
|
|
* R/W the page; let's pray that the page has been
|
|
* used and will be freed some time later.
|
|
* In fact it's dangerous to directly bump up page count from 0,
|
|
* that may make page_ref_freeze()/page_ref_unfreeze() mismatch.
|
|
*/
|
|
if (!(flags & MF_COUNT_INCREASED)) {
|
|
res = get_hwpoison_page(p, flags);
|
|
if (!res) {
|
|
if (is_free_buddy_page(p)) {
|
|
if (take_page_off_buddy(p)) {
|
|
page_ref_inc(p);
|
|
res = MF_RECOVERED;
|
|
} else {
|
|
/* We lost the race, try again */
|
|
if (retry) {
|
|
ClearPageHWPoison(p);
|
|
num_poisoned_pages_dec();
|
|
retry = false;
|
|
goto try_again;
|
|
}
|
|
res = MF_FAILED;
|
|
}
|
|
action_result(pfn, MF_MSG_BUDDY, res);
|
|
res = res == MF_RECOVERED ? 0 : -EBUSY;
|
|
} else {
|
|
action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
|
|
res = -EBUSY;
|
|
}
|
|
goto unlock_mutex;
|
|
} else if (res < 0) {
|
|
action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto unlock_mutex;
|
|
}
|
|
}
|
|
|
|
if (PageTransHuge(hpage)) {
|
|
/*
|
|
* The flag must be set after the refcount is bumped
|
|
* otherwise it may race with THP split.
|
|
* And the flag can't be set in get_hwpoison_page() since
|
|
* it is called by soft offline too and it is just called
|
|
* for !MF_COUNT_INCREASE. So here seems to be the best
|
|
* place.
|
|
*
|
|
* Don't need care about the above error handling paths for
|
|
* get_hwpoison_page() since they handle either free page
|
|
* or unhandlable page. The refcount is bumped iff the
|
|
* page is a valid handlable page.
|
|
*/
|
|
SetPageHasHWPoisoned(hpage);
|
|
if (try_to_split_thp_page(p, "Memory Failure") < 0) {
|
|
action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto unlock_mutex;
|
|
}
|
|
VM_BUG_ON_PAGE(!page_count(p), p);
|
|
}
|
|
|
|
/*
|
|
* We ignore non-LRU pages for good reasons.
|
|
* - PG_locked is only well defined for LRU pages and a few others
|
|
* - to avoid races with __SetPageLocked()
|
|
* - to avoid races with __SetPageSlab*() (and more non-atomic ops)
|
|
* The check (unnecessarily) ignores LRU pages being isolated and
|
|
* walked by the page reclaim code, however that's not a big loss.
|
|
*/
|
|
shake_page(p);
|
|
|
|
lock_page(p);
|
|
|
|
/*
|
|
* The page could have changed compound pages during the locking.
|
|
* If this happens just bail out.
|
|
*/
|
|
if (PageCompound(p) && compound_head(p) != orig_head) {
|
|
action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto unlock_page;
|
|
}
|
|
|
|
/*
|
|
* We use page flags to determine what action should be taken, but
|
|
* the flags can be modified by the error containment action. One
|
|
* example is an mlocked page, where PG_mlocked is cleared by
|
|
* page_remove_rmap() in try_to_unmap_one(). So to determine page status
|
|
* correctly, we save a copy of the page flags at this time.
|
|
*/
|
|
page_flags = p->flags;
|
|
|
|
if (hwpoison_filter(p)) {
|
|
if (TestClearPageHWPoison(p))
|
|
num_poisoned_pages_dec();
|
|
unlock_page(p);
|
|
put_page(p);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
/*
|
|
* __munlock_pagevec may clear a writeback page's LRU flag without
|
|
* page_lock. We need wait writeback completion for this page or it
|
|
* may trigger vfs BUG while evict inode.
|
|
*/
|
|
if (!PageTransTail(p) && !PageLRU(p) && !PageWriteback(p))
|
|
goto identify_page_state;
|
|
|
|
/*
|
|
* It's very difficult to mess with pages currently under IO
|
|
* and in many cases impossible, so we just avoid it here.
|
|
*/
|
|
wait_on_page_writeback(p);
|
|
|
|
/*
|
|
* Now take care of user space mappings.
|
|
* Abort on fail: __delete_from_page_cache() assumes unmapped page.
|
|
*/
|
|
if (!hwpoison_user_mappings(p, pfn, flags, p)) {
|
|
action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto unlock_page;
|
|
}
|
|
|
|
/*
|
|
* Torn down by someone else?
|
|
*/
|
|
if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
|
|
action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
|
|
res = -EBUSY;
|
|
goto unlock_page;
|
|
}
|
|
|
|
identify_page_state:
|
|
res = identify_page_state(pfn, p, page_flags);
|
|
mutex_unlock(&mf_mutex);
|
|
return res;
|
|
unlock_page:
|
|
unlock_page(p);
|
|
unlock_mutex:
|
|
mutex_unlock(&mf_mutex);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL_GPL(memory_failure);
|
|
|
|
#define MEMORY_FAILURE_FIFO_ORDER 4
|
|
#define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER)
|
|
|
|
struct memory_failure_entry {
|
|
unsigned long pfn;
|
|
int flags;
|
|
};
|
|
|
|
struct memory_failure_cpu {
|
|
DECLARE_KFIFO(fifo, struct memory_failure_entry,
|
|
MEMORY_FAILURE_FIFO_SIZE);
|
|
spinlock_t lock;
|
|
struct work_struct work;
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);
|
|
|
|
/**
|
|
* memory_failure_queue - Schedule handling memory failure of a page.
|
|
* @pfn: Page Number of the corrupted page
|
|
* @flags: Flags for memory failure handling
|
|
*
|
|
* This function is called by the low level hardware error handler
|
|
* when it detects hardware memory corruption of a page. It schedules
|
|
* the recovering of error page, including dropping pages, killing
|
|
* processes etc.
|
|
*
|
|
* The function is primarily of use for corruptions that
|
|
* happen outside the current execution context (e.g. when
|
|
* detected by a background scrubber)
|
|
*
|
|
* Can run in IRQ context.
|
|
*/
|
|
void memory_failure_queue(unsigned long pfn, int flags)
|
|
{
|
|
struct memory_failure_cpu *mf_cpu;
|
|
unsigned long proc_flags;
|
|
struct memory_failure_entry entry = {
|
|
.pfn = pfn,
|
|
.flags = flags,
|
|
};
|
|
|
|
mf_cpu = &get_cpu_var(memory_failure_cpu);
|
|
spin_lock_irqsave(&mf_cpu->lock, proc_flags);
|
|
if (kfifo_put(&mf_cpu->fifo, entry))
|
|
schedule_work_on(smp_processor_id(), &mf_cpu->work);
|
|
else
|
|
pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n",
|
|
pfn);
|
|
spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
|
|
put_cpu_var(memory_failure_cpu);
|
|
}
|
|
EXPORT_SYMBOL_GPL(memory_failure_queue);
|
|
|
|
static void memory_failure_work_func(struct work_struct *work)
|
|
{
|
|
struct memory_failure_cpu *mf_cpu;
|
|
struct memory_failure_entry entry = { 0, };
|
|
unsigned long proc_flags;
|
|
int gotten;
|
|
|
|
mf_cpu = container_of(work, struct memory_failure_cpu, work);
|
|
for (;;) {
|
|
spin_lock_irqsave(&mf_cpu->lock, proc_flags);
|
|
gotten = kfifo_get(&mf_cpu->fifo, &entry);
|
|
spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
|
|
if (!gotten)
|
|
break;
|
|
if (entry.flags & MF_SOFT_OFFLINE)
|
|
soft_offline_page(entry.pfn, entry.flags);
|
|
else
|
|
memory_failure(entry.pfn, entry.flags);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Process memory_failure work queued on the specified CPU.
|
|
* Used to avoid return-to-userspace racing with the memory_failure workqueue.
|
|
*/
|
|
void memory_failure_queue_kick(int cpu)
|
|
{
|
|
struct memory_failure_cpu *mf_cpu;
|
|
|
|
mf_cpu = &per_cpu(memory_failure_cpu, cpu);
|
|
cancel_work_sync(&mf_cpu->work);
|
|
memory_failure_work_func(&mf_cpu->work);
|
|
}
|
|
|
|
static int __init memory_failure_init(void)
|
|
{
|
|
struct memory_failure_cpu *mf_cpu;
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
mf_cpu = &per_cpu(memory_failure_cpu, cpu);
|
|
spin_lock_init(&mf_cpu->lock);
|
|
INIT_KFIFO(mf_cpu->fifo);
|
|
INIT_WORK(&mf_cpu->work, memory_failure_work_func);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
core_initcall(memory_failure_init);
|
|
|
|
#define unpoison_pr_info(fmt, pfn, rs) \
|
|
({ \
|
|
if (__ratelimit(rs)) \
|
|
pr_info(fmt, pfn); \
|
|
})
|
|
|
|
static inline int clear_page_hwpoison(struct ratelimit_state *rs, struct page *p)
|
|
{
|
|
if (TestClearPageHWPoison(p)) {
|
|
unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
|
|
page_to_pfn(p), rs);
|
|
num_poisoned_pages_dec();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static inline int unpoison_taken_off_page(struct ratelimit_state *rs,
|
|
struct page *p)
|
|
{
|
|
if (put_page_back_buddy(p)) {
|
|
unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
|
|
page_to_pfn(p), rs);
|
|
return 0;
|
|
}
|
|
return -EBUSY;
|
|
}
|
|
|
|
/**
|
|
* unpoison_memory - Unpoison a previously poisoned page
|
|
* @pfn: Page number of the to be unpoisoned page
|
|
*
|
|
* Software-unpoison a page that has been poisoned by
|
|
* memory_failure() earlier.
|
|
*
|
|
* This is only done on the software-level, so it only works
|
|
* for linux injected failures, not real hardware failures
|
|
*
|
|
* Returns 0 for success, otherwise -errno.
|
|
*/
|
|
int unpoison_memory(unsigned long pfn)
|
|
{
|
|
struct page *page;
|
|
struct page *p;
|
|
int ret = -EBUSY;
|
|
static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
|
|
DEFAULT_RATELIMIT_BURST);
|
|
|
|
if (!pfn_valid(pfn))
|
|
return -ENXIO;
|
|
|
|
p = pfn_to_page(pfn);
|
|
page = compound_head(p);
|
|
|
|
mutex_lock(&mf_mutex);
|
|
|
|
if (!PageHWPoison(p)) {
|
|
unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n",
|
|
pfn, &unpoison_rs);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
if (page_count(page) > 1) {
|
|
unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n",
|
|
pfn, &unpoison_rs);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
if (page_mapped(page)) {
|
|
unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n",
|
|
pfn, &unpoison_rs);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
if (page_mapping(page)) {
|
|
unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n",
|
|
pfn, &unpoison_rs);
|
|
goto unlock_mutex;
|
|
}
|
|
|
|
if (PageSlab(page) || PageTable(page))
|
|
goto unlock_mutex;
|
|
|
|
ret = get_hwpoison_page(p, MF_UNPOISON);
|
|
if (!ret) {
|
|
if (clear_page_hwpoison(&unpoison_rs, page))
|
|
ret = 0;
|
|
else
|
|
ret = -EBUSY;
|
|
} else if (ret < 0) {
|
|
if (ret == -EHWPOISON) {
|
|
ret = unpoison_taken_off_page(&unpoison_rs, p);
|
|
} else
|
|
unpoison_pr_info("Unpoison: failed to grab page %#lx\n",
|
|
pfn, &unpoison_rs);
|
|
} else {
|
|
int freeit = clear_page_hwpoison(&unpoison_rs, p);
|
|
|
|
put_page(page);
|
|
if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) {
|
|
put_page(page);
|
|
ret = 0;
|
|
}
|
|
}
|
|
|
|
unlock_mutex:
|
|
mutex_unlock(&mf_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(unpoison_memory);
|
|
|
|
static bool isolate_page(struct page *page, struct list_head *pagelist)
|
|
{
|
|
bool isolated = false;
|
|
bool lru = PageLRU(page);
|
|
|
|
if (PageHuge(page)) {
|
|
isolated = isolate_huge_page(page, pagelist);
|
|
} else {
|
|
if (lru)
|
|
isolated = !isolate_lru_page(page);
|
|
else
|
|
isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
|
|
|
|
if (isolated)
|
|
list_add(&page->lru, pagelist);
|
|
}
|
|
|
|
if (isolated && lru)
|
|
inc_node_page_state(page, NR_ISOLATED_ANON +
|
|
page_is_file_lru(page));
|
|
|
|
/*
|
|
* If we succeed to isolate the page, we grabbed another refcount on
|
|
* the page, so we can safely drop the one we got from get_any_pages().
|
|
* If we failed to isolate the page, it means that we cannot go further
|
|
* and we will return an error, so drop the reference we got from
|
|
* get_any_pages() as well.
|
|
*/
|
|
put_page(page);
|
|
return isolated;
|
|
}
|
|
|
|
/*
|
|
* __soft_offline_page handles hugetlb-pages and non-hugetlb pages.
|
|
* If the page is a non-dirty unmapped page-cache page, it simply invalidates.
|
|
* If the page is mapped, it migrates the contents over.
|
|
*/
|
|
static int __soft_offline_page(struct page *page)
|
|
{
|
|
int ret = 0;
|
|
unsigned long pfn = page_to_pfn(page);
|
|
struct page *hpage = compound_head(page);
|
|
char const *msg_page[] = {"page", "hugepage"};
|
|
bool huge = PageHuge(page);
|
|
LIST_HEAD(pagelist);
|
|
struct migration_target_control mtc = {
|
|
.nid = NUMA_NO_NODE,
|
|
.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
|
|
};
|
|
|
|
/*
|
|
* Check PageHWPoison again inside page lock because PageHWPoison
|
|
* is set by memory_failure() outside page lock. Note that
|
|
* memory_failure() also double-checks PageHWPoison inside page lock,
|
|
* so there's no race between soft_offline_page() and memory_failure().
|
|
*/
|
|
lock_page(page);
|
|
if (!PageHuge(page))
|
|
wait_on_page_writeback(page);
|
|
if (PageHWPoison(page)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
pr_info("soft offline: %#lx page already poisoned\n", pfn);
|
|
return 0;
|
|
}
|
|
|
|
if (!PageHuge(page))
|
|
/*
|
|
* Try to invalidate first. This should work for
|
|
* non dirty unmapped page cache pages.
|
|
*/
|
|
ret = invalidate_inode_page(page);
|
|
unlock_page(page);
|
|
|
|
/*
|
|
* RED-PEN would be better to keep it isolated here, but we
|
|
* would need to fix isolation locking first.
|
|
*/
|
|
if (ret) {
|
|
pr_info("soft_offline: %#lx: invalidated\n", pfn);
|
|
page_handle_poison(page, false, true);
|
|
return 0;
|
|
}
|
|
|
|
if (isolate_page(hpage, &pagelist)) {
|
|
ret = migrate_pages(&pagelist, alloc_migration_target, NULL,
|
|
(unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_FAILURE, NULL);
|
|
if (!ret) {
|
|
bool release = !huge;
|
|
|
|
if (!page_handle_poison(page, huge, release))
|
|
ret = -EBUSY;
|
|
} else {
|
|
if (!list_empty(&pagelist))
|
|
putback_movable_pages(&pagelist);
|
|
|
|
pr_info("soft offline: %#lx: %s migration failed %d, type %pGp\n",
|
|
pfn, msg_page[huge], ret, &page->flags);
|
|
if (ret > 0)
|
|
ret = -EBUSY;
|
|
}
|
|
} else {
|
|
pr_info("soft offline: %#lx: %s isolation failed, page count %d, type %pGp\n",
|
|
pfn, msg_page[huge], page_count(page), &page->flags);
|
|
ret = -EBUSY;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int soft_offline_in_use_page(struct page *page)
|
|
{
|
|
struct page *hpage = compound_head(page);
|
|
|
|
if (!PageHuge(page) && PageTransHuge(hpage))
|
|
if (try_to_split_thp_page(page, "soft offline") < 0)
|
|
return -EBUSY;
|
|
return __soft_offline_page(page);
|
|
}
|
|
|
|
static int soft_offline_free_page(struct page *page)
|
|
{
|
|
int rc = 0;
|
|
|
|
if (!page_handle_poison(page, true, false))
|
|
rc = -EBUSY;
|
|
|
|
return rc;
|
|
}
|
|
|
|
static void put_ref_page(struct page *page)
|
|
{
|
|
if (page)
|
|
put_page(page);
|
|
}
|
|
|
|
/**
|
|
* soft_offline_page - Soft offline a page.
|
|
* @pfn: pfn to soft-offline
|
|
* @flags: flags. Same as memory_failure().
|
|
*
|
|
* Returns 0 on success, otherwise negated errno.
|
|
*
|
|
* Soft offline a page, by migration or invalidation,
|
|
* without killing anything. This is for the case when
|
|
* a page is not corrupted yet (so it's still valid to access),
|
|
* but has had a number of corrected errors and is better taken
|
|
* out.
|
|
*
|
|
* The actual policy on when to do that is maintained by
|
|
* user space.
|
|
*
|
|
* This should never impact any application or cause data loss,
|
|
* however it might take some time.
|
|
*
|
|
* This is not a 100% solution for all memory, but tries to be
|
|
* ``good enough'' for the majority of memory.
|
|
*/
|
|
int soft_offline_page(unsigned long pfn, int flags)
|
|
{
|
|
int ret;
|
|
bool try_again = true;
|
|
struct page *page, *ref_page = NULL;
|
|
|
|
WARN_ON_ONCE(!pfn_valid(pfn) && (flags & MF_COUNT_INCREASED));
|
|
|
|
if (!pfn_valid(pfn))
|
|
return -ENXIO;
|
|
if (flags & MF_COUNT_INCREASED)
|
|
ref_page = pfn_to_page(pfn);
|
|
|
|
/* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
|
|
page = pfn_to_online_page(pfn);
|
|
if (!page) {
|
|
put_ref_page(ref_page);
|
|
return -EIO;
|
|
}
|
|
|
|
mutex_lock(&mf_mutex);
|
|
|
|
if (PageHWPoison(page)) {
|
|
pr_info("%s: %#lx page already poisoned\n", __func__, pfn);
|
|
put_ref_page(ref_page);
|
|
mutex_unlock(&mf_mutex);
|
|
return 0;
|
|
}
|
|
|
|
retry:
|
|
get_online_mems();
|
|
ret = get_hwpoison_page(page, flags);
|
|
put_online_mems();
|
|
|
|
if (ret > 0) {
|
|
ret = soft_offline_in_use_page(page);
|
|
} else if (ret == 0) {
|
|
if (soft_offline_free_page(page) && try_again) {
|
|
try_again = false;
|
|
flags &= ~MF_COUNT_INCREASED;
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
mutex_unlock(&mf_mutex);
|
|
|
|
return ret;
|
|
}
|