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* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits) Documentation/iostats.txt: bit-size reference etc. cfq-iosched: removing unnecessary think time checking cfq-iosched: Don't clear queue stats when preempt. blk-throttle: Reset group slice when limits are changed blk-cgroup: Only give unaccounted_time under debug cfq-iosched: Don't set active queue in preempt block: fix non-atomic access to genhd inflight structures block: attempt to merge with existing requests on plug flush block: NULL dereference on error path in __blkdev_get() cfq-iosched: Don't update group weights when on service tree fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away block: Require subsystems to explicitly allocate bio_set integrity mempool jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging fs: make fsync_buffers_list() plug mm: make generic_writepages() use plugging blk-cgroup: Add unaccounted time to timeslice_used. block: fixup plugging stubs for !CONFIG_BLOCK block: remove obsolete comments for blkdev_issue_zeroout. blktrace: Use rq->cmd_flags directly in blk_add_trace_rq. ... Fix up conflicts in fs/{aio.c,super.c}
1489 lines
39 KiB
C
1489 lines
39 KiB
C
/*
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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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* This software may be redistributed and/or modified under the terms of
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* the GNU General Public License ("GPL") version 2 only as published by the
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* Free Software Foundation.
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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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* 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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/*
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* Notebook:
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* - hugetlb needs more code
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* - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages
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* - pass bad pages to kdump next kernel
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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.h>
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#include <linux/ksm.h>
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#include <linux/rmap.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/page-isolation.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 "internal.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 mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);
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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_CGROUP_MEM_RES_CTLR_SWAP
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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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struct mem_cgroup *mem;
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struct cgroup_subsys_state *css;
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unsigned long ino;
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if (!hwpoison_filter_memcg)
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return 0;
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mem = try_get_mem_cgroup_from_page(p);
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if (!mem)
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return -EINVAL;
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css = mem_cgroup_css(mem);
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/* root_mem_cgroup has NULL dentries */
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if (!css->cgroup->dentry)
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return -EINVAL;
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ino = css->cgroup->dentry->d_inode->i_ino;
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css_put(css);
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if (ino != 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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* Send all the processes who have the page mapped an ``action optional''
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* signal.
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*/
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static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
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unsigned long pfn, struct page *page)
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{
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struct siginfo si;
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int ret;
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printk(KERN_ERR
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"MCE %#lx: Killing %s:%d early due to hardware memory corruption\n",
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pfn, t->comm, t->pid);
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si.si_signo = SIGBUS;
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si.si_errno = 0;
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si.si_code = BUS_MCEERR_AO;
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si.si_addr = (void *)addr;
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#ifdef __ARCH_SI_TRAPNO
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si.si_trapno = trapno;
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#endif
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si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
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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 noone will do that?
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*/
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ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */
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if (ret < 0)
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printk(KERN_INFO "MCE: 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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* When a unknown page type is encountered drain as many buffers as possible
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* in the hope to turn the page into a LRU or free page, which we can handle.
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*/
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void shake_page(struct page *p, int access)
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{
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if (!PageSlab(p)) {
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lru_add_drain_all();
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if (PageLRU(p))
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return;
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drain_all_pages();
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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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* Only call shrink_slab here (which would also shrink other caches) if
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* access is not potentially fatal.
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*/
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if (access) {
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int nr;
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do {
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nr = shrink_slab(1000, GFP_KERNEL, 1000);
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if (page_count(p) == 1)
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break;
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} while (nr > 10);
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}
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}
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EXPORT_SYMBOL_GPL(shake_page);
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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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char addr_valid;
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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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* TBD would GFP_NOIO be enough?
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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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struct to_kill **tkc)
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{
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struct to_kill *tk;
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if (*tkc) {
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tk = *tkc;
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*tkc = NULL;
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} else {
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tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
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if (!tk) {
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printk(KERN_ERR
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"MCE: Out of memory while machine check handling\n");
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return;
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}
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}
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tk->addr = page_address_in_vma(p, vma);
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tk->addr_valid = 1;
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/*
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* In theory we don't have to kill when the page was
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* munmaped. But it could be also a mremap. Since that's
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* likely very rare kill anyways just out of paranoia, but use
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* a SIGKILL because the error is not contained anymore.
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*/
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if (tk->addr == -EFAULT) {
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pr_info("MCE: Unable to find user space address %lx in %s\n",
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page_to_pfn(p), tsk->comm);
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tk->addr_valid = 0;
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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 DOIT is set, otherwise just free the list
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* (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_ao(struct list_head *to_kill, int doit, int trapno,
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int fail, struct page *page, unsigned long pfn)
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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 (doit) {
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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_valid == 0) {
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printk(KERN_ERR
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"MCE %#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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force_sig(SIGKILL, tk->tsk);
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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_ao(tk->tsk, tk->addr, trapno,
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pfn, page) < 0)
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printk(KERN_ERR
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"MCE %#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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static int task_early_kill(struct task_struct *tsk)
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{
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if (!tsk->mm)
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return 0;
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if (tsk->flags & PF_MCE_PROCESS)
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return !!(tsk->flags & PF_MCE_EARLY);
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return sysctl_memory_failure_early_kill;
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}
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/*
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* Collect processes when the error hit an anonymous page.
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*/
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static void collect_procs_anon(struct page *page, struct list_head *to_kill,
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struct to_kill **tkc)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk;
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struct anon_vma *av;
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read_lock(&tasklist_lock);
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av = page_lock_anon_vma(page);
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if (av == NULL) /* Not actually mapped anymore */
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goto out;
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for_each_process (tsk) {
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struct anon_vma_chain *vmac;
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if (!task_early_kill(tsk))
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continue;
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list_for_each_entry(vmac, &av->head, same_anon_vma) {
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vma = vmac->vma;
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if (!page_mapped_in_vma(page, vma))
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continue;
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if (vma->vm_mm == tsk->mm)
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add_to_kill(tsk, page, vma, to_kill, tkc);
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}
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}
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page_unlock_anon_vma(av);
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out:
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read_unlock(&tasklist_lock);
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}
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|
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/*
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* Collect processes when the error hit a file mapped page.
|
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*/
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static void collect_procs_file(struct page *page, struct list_head *to_kill,
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struct to_kill **tkc)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk;
|
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struct prio_tree_iter iter;
|
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struct address_space *mapping = page->mapping;
|
|
|
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/*
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* A note on the locking order between the two locks.
|
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* We don't rely on this particular order.
|
|
* If you have some other code that needs a different order
|
|
* feel free to switch them around. Or add a reverse link
|
|
* from mm_struct to task_struct, then this could be all
|
|
* done without taking tasklist_lock and looping over all tasks.
|
|
*/
|
|
|
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read_lock(&tasklist_lock);
|
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spin_lock(&mapping->i_mmap_lock);
|
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for_each_process(tsk) {
|
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pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
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|
|
if (!task_early_kill(tsk))
|
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continue;
|
|
|
|
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff,
|
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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 == tsk->mm)
|
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add_to_kill(tsk, page, vma, to_kill, tkc);
|
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}
|
|
}
|
|
spin_unlock(&mapping->i_mmap_lock);
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
/*
|
|
* Collect the processes who have the corrupted page mapped to kill.
|
|
* This is done in two steps for locking reasons.
|
|
* First preallocate one tokill structure outside the spin locks,
|
|
* so that we can kill at least one process reasonably reliable.
|
|
*/
|
|
static void collect_procs(struct page *page, struct list_head *tokill)
|
|
{
|
|
struct to_kill *tk;
|
|
|
|
if (!page->mapping)
|
|
return;
|
|
|
|
tk = kmalloc(sizeof(struct to_kill), GFP_NOIO);
|
|
if (!tk)
|
|
return;
|
|
if (PageAnon(page))
|
|
collect_procs_anon(page, tokill, &tk);
|
|
else
|
|
collect_procs_file(page, tokill, &tk);
|
|
kfree(tk);
|
|
}
|
|
|
|
/*
|
|
* Error handlers for various types of pages.
|
|
*/
|
|
|
|
enum outcome {
|
|
IGNORED, /* Error: cannot be handled */
|
|
FAILED, /* Error: handling failed */
|
|
DELAYED, /* Will be handled later */
|
|
RECOVERED, /* Successfully recovered */
|
|
};
|
|
|
|
static const char *action_name[] = {
|
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[IGNORED] = "Ignored",
|
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[FAILED] = "Failed",
|
|
[DELAYED] = "Delayed",
|
|
[RECOVERED] = "Recovered",
|
|
};
|
|
|
|
/*
|
|
* 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);
|
|
/*
|
|
* drop the page count elevated by isolate_lru_page()
|
|
*/
|
|
page_cache_release(p);
|
|
return 0;
|
|
}
|
|
return -EIO;
|
|
}
|
|
|
|
/*
|
|
* 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 *p, unsigned long pfn)
|
|
{
|
|
return IGNORED;
|
|
}
|
|
|
|
/*
|
|
* Page in unknown state. Do nothing.
|
|
*/
|
|
static int me_unknown(struct page *p, unsigned long pfn)
|
|
{
|
|
printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn);
|
|
return FAILED;
|
|
}
|
|
|
|
/*
|
|
* Clean (or cleaned) page cache page.
|
|
*/
|
|
static int me_pagecache_clean(struct page *p, unsigned long pfn)
|
|
{
|
|
int err;
|
|
int ret = FAILED;
|
|
struct address_space *mapping;
|
|
|
|
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))
|
|
return RECOVERED;
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
return FAILED;
|
|
}
|
|
|
|
/*
|
|
* Truncation is a bit tricky. Enable it per file system for now.
|
|
*
|
|
* Open: to take i_mutex or not for this? Right now we don't.
|
|
*/
|
|
if (mapping->a_ops->error_remove_page) {
|
|
err = mapping->a_ops->error_remove_page(mapping, p);
|
|
if (err != 0) {
|
|
printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n",
|
|
pfn, err);
|
|
} else if (page_has_private(p) &&
|
|
!try_to_release_page(p, GFP_NOIO)) {
|
|
pr_info("MCE %#lx: failed to release buffers\n", pfn);
|
|
} else {
|
|
ret = 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 = RECOVERED;
|
|
else
|
|
printk(KERN_INFO "MCE %#lx: Failed to invalidate\n",
|
|
pfn);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Dirty cache page page
|
|
* Issues: when the error hit a hole page the error is not properly
|
|
* propagated.
|
|
*/
|
|
static int me_pagecache_dirty(struct page *p, unsigned long pfn)
|
|
{
|
|
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 inbetween 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(p, pfn);
|
|
}
|
|
|
|
/*
|
|
* 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 *p, unsigned long pfn)
|
|
{
|
|
ClearPageDirty(p);
|
|
/* Trigger EIO in shmem: */
|
|
ClearPageUptodate(p);
|
|
|
|
if (!delete_from_lru_cache(p))
|
|
return DELAYED;
|
|
else
|
|
return FAILED;
|
|
}
|
|
|
|
static int me_swapcache_clean(struct page *p, unsigned long pfn)
|
|
{
|
|
delete_from_swap_cache(p);
|
|
|
|
if (!delete_from_lru_cache(p))
|
|
return RECOVERED;
|
|
else
|
|
return FAILED;
|
|
}
|
|
|
|
/*
|
|
* 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 *p, unsigned long pfn)
|
|
{
|
|
int res = 0;
|
|
struct page *hpage = compound_head(p);
|
|
/*
|
|
* We can safely recover from error on free or reserved (i.e.
|
|
* not in-use) hugepage by dequeuing it from freelist.
|
|
* To check whether a hugepage is in-use or not, we can't use
|
|
* page->lru because it can be used in other hugepage operations,
|
|
* such as __unmap_hugepage_range() and gather_surplus_pages().
|
|
* So instead we use page_mapping() and PageAnon().
|
|
* We assume that this function is called with page lock held,
|
|
* so there is no race between isolation and mapping/unmapping.
|
|
*/
|
|
if (!(page_mapping(hpage) || PageAnon(hpage))) {
|
|
res = dequeue_hwpoisoned_huge_page(hpage);
|
|
if (!res)
|
|
return RECOVERED;
|
|
}
|
|
return DELAYED;
|
|
}
|
|
|
|
/*
|
|
* 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 extremly 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)
|
|
#define unevict (1UL << PG_unevictable)
|
|
#define mlock (1UL << PG_mlocked)
|
|
#define writeback (1UL << PG_writeback)
|
|
#define lru (1UL << PG_lru)
|
|
#define swapbacked (1UL << PG_swapbacked)
|
|
#define head (1UL << PG_head)
|
|
#define tail (1UL << PG_tail)
|
|
#define compound (1UL << PG_compound)
|
|
#define slab (1UL << PG_slab)
|
|
#define reserved (1UL << PG_reserved)
|
|
|
|
static struct page_state {
|
|
unsigned long mask;
|
|
unsigned long res;
|
|
char *msg;
|
|
int (*action)(struct page *p, unsigned long pfn);
|
|
} error_states[] = {
|
|
{ reserved, reserved, "reserved 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, "kernel slab", me_kernel },
|
|
|
|
#ifdef CONFIG_PAGEFLAGS_EXTENDED
|
|
{ head, head, "huge", me_huge_page },
|
|
{ tail, tail, "huge", me_huge_page },
|
|
#else
|
|
{ compound, compound, "huge", me_huge_page },
|
|
#endif
|
|
|
|
{ sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty },
|
|
{ sc|dirty, sc, "swapcache", me_swapcache_clean },
|
|
|
|
{ unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
|
|
{ unevict, unevict, "unevictable LRU", me_pagecache_clean},
|
|
|
|
{ mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
|
|
{ mlock, mlock, "mlocked LRU", me_pagecache_clean },
|
|
|
|
{ lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
|
|
{ lru|dirty, lru, "clean LRU", me_pagecache_clean },
|
|
|
|
/*
|
|
* Catchall entry: must be at end.
|
|
*/
|
|
{ 0, 0, "unknown page state", me_unknown },
|
|
};
|
|
|
|
#undef dirty
|
|
#undef sc
|
|
#undef unevict
|
|
#undef mlock
|
|
#undef writeback
|
|
#undef lru
|
|
#undef swapbacked
|
|
#undef head
|
|
#undef tail
|
|
#undef compound
|
|
#undef slab
|
|
#undef reserved
|
|
|
|
static void action_result(unsigned long pfn, char *msg, int result)
|
|
{
|
|
struct page *page = pfn_to_page(pfn);
|
|
|
|
printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
|
|
pfn,
|
|
PageDirty(page) ? "dirty " : "",
|
|
msg, action_name[result]);
|
|
}
|
|
|
|
static int page_action(struct page_state *ps, struct page *p,
|
|
unsigned long pfn)
|
|
{
|
|
int result;
|
|
int count;
|
|
|
|
result = ps->action(p, pfn);
|
|
action_result(pfn, ps->msg, result);
|
|
|
|
count = page_count(p) - 1;
|
|
if (ps->action == me_swapcache_dirty && result == DELAYED)
|
|
count--;
|
|
if (count != 0) {
|
|
printk(KERN_ERR
|
|
"MCE %#lx: %s page still referenced by %d users\n",
|
|
pfn, ps->msg, count);
|
|
result = FAILED;
|
|
}
|
|
|
|
/* Could do more checks here if page looks ok */
|
|
/*
|
|
* Could adjust zone counters here to correct for the missing page.
|
|
*/
|
|
|
|
return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
|
|
}
|
|
|
|
/*
|
|
* 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 int hwpoison_user_mappings(struct page *p, unsigned long pfn,
|
|
int trapno)
|
|
{
|
|
enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
|
|
struct address_space *mapping;
|
|
LIST_HEAD(tokill);
|
|
int ret;
|
|
int kill = 1;
|
|
struct page *hpage = compound_head(p);
|
|
struct page *ppage;
|
|
|
|
if (PageReserved(p) || PageSlab(p))
|
|
return SWAP_SUCCESS;
|
|
|
|
/*
|
|
* 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 SWAP_SUCCESS;
|
|
|
|
if (PageKsm(p))
|
|
return SWAP_FAIL;
|
|
|
|
if (PageSwapCache(p)) {
|
|
printk(KERN_ERR
|
|
"MCE %#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 (!PageDirty(hpage) && mapping &&
|
|
mapping_cap_writeback_dirty(mapping)) {
|
|
if (page_mkclean(hpage)) {
|
|
SetPageDirty(hpage);
|
|
} else {
|
|
kill = 0;
|
|
ttu |= TTU_IGNORE_HWPOISON;
|
|
printk(KERN_INFO
|
|
"MCE %#lx: corrupted page was clean: dropped without side effects\n",
|
|
pfn);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* ppage: poisoned page
|
|
* if p is regular page(4k page)
|
|
* ppage == real poisoned page;
|
|
* else p is hugetlb or THP, ppage == head page.
|
|
*/
|
|
ppage = hpage;
|
|
|
|
if (PageTransHuge(hpage)) {
|
|
/*
|
|
* Verify that this isn't a hugetlbfs head page, the check for
|
|
* PageAnon is just for avoid tripping a split_huge_page
|
|
* internal debug check, as split_huge_page refuses to deal with
|
|
* anything that isn't an anon page. PageAnon can't go away fro
|
|
* under us because we hold a refcount on the hpage, without a
|
|
* refcount on the hpage. split_huge_page can't be safely called
|
|
* in the first place, having a refcount on the tail isn't
|
|
* enough * to be safe.
|
|
*/
|
|
if (!PageHuge(hpage) && PageAnon(hpage)) {
|
|
if (unlikely(split_huge_page(hpage))) {
|
|
/*
|
|
* FIXME: if splitting THP is failed, it is
|
|
* better to stop the following operation rather
|
|
* than causing panic by unmapping. System might
|
|
* survive if the page is freed later.
|
|
*/
|
|
printk(KERN_INFO
|
|
"MCE %#lx: failed to split THP\n", pfn);
|
|
|
|
BUG_ON(!PageHWPoison(p));
|
|
return SWAP_FAIL;
|
|
}
|
|
/* THP is split, so ppage should be the real poisoned page. */
|
|
ppage = p;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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(ppage, &tokill);
|
|
|
|
if (hpage != ppage)
|
|
lock_page(ppage);
|
|
|
|
ret = try_to_unmap(ppage, ttu);
|
|
if (ret != SWAP_SUCCESS)
|
|
printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
|
|
pfn, page_mapcount(ppage));
|
|
|
|
if (hpage != ppage)
|
|
unlock_page(ppage);
|
|
|
|
/*
|
|
* 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, 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.
|
|
*/
|
|
kill_procs_ao(&tokill, !!PageDirty(ppage), trapno,
|
|
ret != SWAP_SUCCESS, p, pfn);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void set_page_hwpoison_huge_page(struct page *hpage)
|
|
{
|
|
int i;
|
|
int nr_pages = 1 << compound_trans_order(hpage);
|
|
for (i = 0; i < nr_pages; i++)
|
|
SetPageHWPoison(hpage + i);
|
|
}
|
|
|
|
static void clear_page_hwpoison_huge_page(struct page *hpage)
|
|
{
|
|
int i;
|
|
int nr_pages = 1 << compound_trans_order(hpage);
|
|
for (i = 0; i < nr_pages; i++)
|
|
ClearPageHWPoison(hpage + i);
|
|
}
|
|
|
|
int __memory_failure(unsigned long pfn, int trapno, int flags)
|
|
{
|
|
struct page_state *ps;
|
|
struct page *p;
|
|
struct page *hpage;
|
|
int res;
|
|
unsigned int nr_pages;
|
|
|
|
if (!sysctl_memory_failure_recovery)
|
|
panic("Memory failure from trap %d on page %lx", trapno, pfn);
|
|
|
|
if (!pfn_valid(pfn)) {
|
|
printk(KERN_ERR
|
|
"MCE %#lx: memory outside kernel control\n",
|
|
pfn);
|
|
return -ENXIO;
|
|
}
|
|
|
|
p = pfn_to_page(pfn);
|
|
hpage = compound_head(p);
|
|
if (TestSetPageHWPoison(p)) {
|
|
printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
|
|
return 0;
|
|
}
|
|
|
|
nr_pages = 1 << compound_trans_order(hpage);
|
|
atomic_long_add(nr_pages, &mce_bad_pages);
|
|
|
|
/*
|
|
* 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 a free hugepage, which is also safe:
|
|
* an affected hugepage will be dequeued from hugepage freelist,
|
|
* so there's no concern about reusing it ever after.
|
|
* 3) 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_freeze_refs()/page_unfreeze_refs() mismatch.
|
|
*/
|
|
if (!(flags & MF_COUNT_INCREASED) &&
|
|
!get_page_unless_zero(hpage)) {
|
|
if (is_free_buddy_page(p)) {
|
|
action_result(pfn, "free buddy", DELAYED);
|
|
return 0;
|
|
} else if (PageHuge(hpage)) {
|
|
/*
|
|
* Check "just unpoisoned", "filter hit", and
|
|
* "race with other subpage."
|
|
*/
|
|
lock_page(hpage);
|
|
if (!PageHWPoison(hpage)
|
|
|| (hwpoison_filter(p) && TestClearPageHWPoison(p))
|
|
|| (p != hpage && TestSetPageHWPoison(hpage))) {
|
|
atomic_long_sub(nr_pages, &mce_bad_pages);
|
|
return 0;
|
|
}
|
|
set_page_hwpoison_huge_page(hpage);
|
|
res = dequeue_hwpoisoned_huge_page(hpage);
|
|
action_result(pfn, "free huge",
|
|
res ? IGNORED : DELAYED);
|
|
unlock_page(hpage);
|
|
return res;
|
|
} else {
|
|
action_result(pfn, "high order kernel", IGNORED);
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 __set_page_locked()
|
|
* - 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.
|
|
*/
|
|
if (!PageHuge(p) && !PageTransCompound(p)) {
|
|
if (!PageLRU(p))
|
|
shake_page(p, 0);
|
|
if (!PageLRU(p)) {
|
|
/*
|
|
* shake_page could have turned it free.
|
|
*/
|
|
if (is_free_buddy_page(p)) {
|
|
action_result(pfn, "free buddy, 2nd try",
|
|
DELAYED);
|
|
return 0;
|
|
}
|
|
action_result(pfn, "non LRU", IGNORED);
|
|
put_page(p);
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Lock the page and wait for writeback to finish.
|
|
* It's very difficult to mess with pages currently under IO
|
|
* and in many cases impossible, so we just avoid it here.
|
|
*/
|
|
lock_page(hpage);
|
|
|
|
/*
|
|
* unpoison always clear PG_hwpoison inside page lock
|
|
*/
|
|
if (!PageHWPoison(p)) {
|
|
printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
|
|
res = 0;
|
|
goto out;
|
|
}
|
|
if (hwpoison_filter(p)) {
|
|
if (TestClearPageHWPoison(p))
|
|
atomic_long_sub(nr_pages, &mce_bad_pages);
|
|
unlock_page(hpage);
|
|
put_page(hpage);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* For error on the tail page, we should set PG_hwpoison
|
|
* on the head page to show that the hugepage is hwpoisoned
|
|
*/
|
|
if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) {
|
|
action_result(pfn, "hugepage already hardware poisoned",
|
|
IGNORED);
|
|
unlock_page(hpage);
|
|
put_page(hpage);
|
|
return 0;
|
|
}
|
|
/*
|
|
* Set PG_hwpoison on all pages in an error hugepage,
|
|
* because containment is done in hugepage unit for now.
|
|
* Since we have done TestSetPageHWPoison() for the head page with
|
|
* page lock held, we can safely set PG_hwpoison bits on tail pages.
|
|
*/
|
|
if (PageHuge(p))
|
|
set_page_hwpoison_huge_page(hpage);
|
|
|
|
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, trapno) != SWAP_SUCCESS) {
|
|
printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn);
|
|
res = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Torn down by someone else?
|
|
*/
|
|
if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
|
|
action_result(pfn, "already truncated LRU", IGNORED);
|
|
res = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
res = -EBUSY;
|
|
for (ps = error_states;; ps++) {
|
|
if ((p->flags & ps->mask) == ps->res) {
|
|
res = page_action(ps, p, pfn);
|
|
break;
|
|
}
|
|
}
|
|
out:
|
|
unlock_page(hpage);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__memory_failure);
|
|
|
|
/**
|
|
* memory_failure - Handle memory failure of a page.
|
|
* @pfn: Page Number of the corrupted page
|
|
* @trapno: Trap number reported in the signal to user space.
|
|
*
|
|
* 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.
|
|
*/
|
|
void memory_failure(unsigned long pfn, int trapno)
|
|
{
|
|
__memory_failure(pfn, trapno, 0);
|
|
}
|
|
|
|
/**
|
|
* 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 freeit = 0;
|
|
unsigned int nr_pages;
|
|
|
|
if (!pfn_valid(pfn))
|
|
return -ENXIO;
|
|
|
|
p = pfn_to_page(pfn);
|
|
page = compound_head(p);
|
|
|
|
if (!PageHWPoison(p)) {
|
|
pr_info("MCE: Page was already unpoisoned %#lx\n", pfn);
|
|
return 0;
|
|
}
|
|
|
|
nr_pages = 1 << compound_trans_order(page);
|
|
|
|
if (!get_page_unless_zero(page)) {
|
|
/*
|
|
* Since HWPoisoned hugepage should have non-zero refcount,
|
|
* race between memory failure and unpoison seems to happen.
|
|
* In such case unpoison fails and memory failure runs
|
|
* to the end.
|
|
*/
|
|
if (PageHuge(page)) {
|
|
pr_debug("MCE: Memory failure is now running on free hugepage %#lx\n", pfn);
|
|
return 0;
|
|
}
|
|
if (TestClearPageHWPoison(p))
|
|
atomic_long_sub(nr_pages, &mce_bad_pages);
|
|
pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
|
|
return 0;
|
|
}
|
|
|
|
lock_page(page);
|
|
/*
|
|
* This test is racy because PG_hwpoison is set outside of page lock.
|
|
* That's acceptable because that won't trigger kernel panic. Instead,
|
|
* the PG_hwpoison page will be caught and isolated on the entrance to
|
|
* the free buddy page pool.
|
|
*/
|
|
if (TestClearPageHWPoison(page)) {
|
|
pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
|
|
atomic_long_sub(nr_pages, &mce_bad_pages);
|
|
freeit = 1;
|
|
if (PageHuge(page))
|
|
clear_page_hwpoison_huge_page(page);
|
|
}
|
|
unlock_page(page);
|
|
|
|
put_page(page);
|
|
if (freeit)
|
|
put_page(page);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(unpoison_memory);
|
|
|
|
static struct page *new_page(struct page *p, unsigned long private, int **x)
|
|
{
|
|
int nid = page_to_nid(p);
|
|
if (PageHuge(p))
|
|
return alloc_huge_page_node(page_hstate(compound_head(p)),
|
|
nid);
|
|
else
|
|
return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
|
|
}
|
|
|
|
/*
|
|
* Safely get reference count of an arbitrary page.
|
|
* Returns 0 for a free page, -EIO for a zero refcount page
|
|
* that is not free, and 1 for any other page type.
|
|
* For 1 the page is returned with increased page count, otherwise not.
|
|
*/
|
|
static int get_any_page(struct page *p, unsigned long pfn, int flags)
|
|
{
|
|
int ret;
|
|
|
|
if (flags & MF_COUNT_INCREASED)
|
|
return 1;
|
|
|
|
/*
|
|
* The lock_memory_hotplug prevents a race with memory hotplug.
|
|
* This is a big hammer, a better would be nicer.
|
|
*/
|
|
lock_memory_hotplug();
|
|
|
|
/*
|
|
* Isolate the page, so that it doesn't get reallocated if it
|
|
* was free.
|
|
*/
|
|
set_migratetype_isolate(p);
|
|
/*
|
|
* When the target page is a free hugepage, just remove it
|
|
* from free hugepage list.
|
|
*/
|
|
if (!get_page_unless_zero(compound_head(p))) {
|
|
if (PageHuge(p)) {
|
|
pr_info("get_any_page: %#lx free huge page\n", pfn);
|
|
ret = dequeue_hwpoisoned_huge_page(compound_head(p));
|
|
} else if (is_free_buddy_page(p)) {
|
|
pr_info("get_any_page: %#lx free buddy page\n", pfn);
|
|
/* Set hwpoison bit while page is still isolated */
|
|
SetPageHWPoison(p);
|
|
ret = 0;
|
|
} else {
|
|
pr_info("get_any_page: %#lx: unknown zero refcount page type %lx\n",
|
|
pfn, p->flags);
|
|
ret = -EIO;
|
|
}
|
|
} else {
|
|
/* Not a free page */
|
|
ret = 1;
|
|
}
|
|
unset_migratetype_isolate(p);
|
|
unlock_memory_hotplug();
|
|
return ret;
|
|
}
|
|
|
|
static int soft_offline_huge_page(struct page *page, int flags)
|
|
{
|
|
int ret;
|
|
unsigned long pfn = page_to_pfn(page);
|
|
struct page *hpage = compound_head(page);
|
|
LIST_HEAD(pagelist);
|
|
|
|
ret = get_any_page(page, pfn, flags);
|
|
if (ret < 0)
|
|
return ret;
|
|
if (ret == 0)
|
|
goto done;
|
|
|
|
if (PageHWPoison(hpage)) {
|
|
put_page(hpage);
|
|
pr_debug("soft offline: %#lx hugepage already poisoned\n", pfn);
|
|
return -EBUSY;
|
|
}
|
|
|
|
/* Keep page count to indicate a given hugepage is isolated. */
|
|
|
|
list_add(&hpage->lru, &pagelist);
|
|
ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0,
|
|
true);
|
|
if (ret) {
|
|
struct page *page1, *page2;
|
|
list_for_each_entry_safe(page1, page2, &pagelist, lru)
|
|
put_page(page1);
|
|
|
|
pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
|
|
pfn, ret, page->flags);
|
|
if (ret > 0)
|
|
ret = -EIO;
|
|
return ret;
|
|
}
|
|
done:
|
|
if (!PageHWPoison(hpage))
|
|
atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages);
|
|
set_page_hwpoison_huge_page(hpage);
|
|
dequeue_hwpoisoned_huge_page(hpage);
|
|
/* keep elevated page count for bad page */
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* soft_offline_page - Soft offline a page.
|
|
* @page: page to 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(struct page *page, int flags)
|
|
{
|
|
int ret;
|
|
unsigned long pfn = page_to_pfn(page);
|
|
|
|
if (PageHuge(page))
|
|
return soft_offline_huge_page(page, flags);
|
|
|
|
ret = get_any_page(page, pfn, flags);
|
|
if (ret < 0)
|
|
return ret;
|
|
if (ret == 0)
|
|
goto done;
|
|
|
|
/*
|
|
* Page cache page we can handle?
|
|
*/
|
|
if (!PageLRU(page)) {
|
|
/*
|
|
* Try to free it.
|
|
*/
|
|
put_page(page);
|
|
shake_page(page, 1);
|
|
|
|
/*
|
|
* Did it turn free?
|
|
*/
|
|
ret = get_any_page(page, pfn, 0);
|
|
if (ret < 0)
|
|
return ret;
|
|
if (ret == 0)
|
|
goto done;
|
|
}
|
|
if (!PageLRU(page)) {
|
|
pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
|
|
pfn, page->flags);
|
|
return -EIO;
|
|
}
|
|
|
|
lock_page(page);
|
|
wait_on_page_writeback(page);
|
|
|
|
/*
|
|
* Synchronized using the page lock with memory_failure()
|
|
*/
|
|
if (PageHWPoison(page)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
pr_info("soft offline: %#lx page already poisoned\n", pfn);
|
|
return -EBUSY;
|
|
}
|
|
|
|
/*
|
|
* Try to invalidate first. This should work for
|
|
* non dirty unmapped page cache pages.
|
|
*/
|
|
ret = invalidate_inode_page(page);
|
|
unlock_page(page);
|
|
|
|
/*
|
|
* Drop count because page migration doesn't like raised
|
|
* counts. The page could get re-allocated, but if it becomes
|
|
* LRU the isolation will just fail.
|
|
* RED-PEN would be better to keep it isolated here, but we
|
|
* would need to fix isolation locking first.
|
|
*/
|
|
put_page(page);
|
|
if (ret == 1) {
|
|
ret = 0;
|
|
pr_info("soft_offline: %#lx: invalidated\n", pfn);
|
|
goto done;
|
|
}
|
|
|
|
/*
|
|
* Simple invalidation didn't work.
|
|
* Try to migrate to a new page instead. migrate.c
|
|
* handles a large number of cases for us.
|
|
*/
|
|
ret = isolate_lru_page(page);
|
|
if (!ret) {
|
|
LIST_HEAD(pagelist);
|
|
|
|
list_add(&page->lru, &pagelist);
|
|
ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
|
|
0, true);
|
|
if (ret) {
|
|
putback_lru_pages(&pagelist);
|
|
pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
|
|
pfn, ret, page->flags);
|
|
if (ret > 0)
|
|
ret = -EIO;
|
|
}
|
|
} else {
|
|
pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
|
|
pfn, ret, page_count(page), page->flags);
|
|
}
|
|
if (ret)
|
|
return ret;
|
|
|
|
done:
|
|
atomic_long_add(1, &mce_bad_pages);
|
|
SetPageHWPoison(page);
|
|
/* keep elevated page count for bad page */
|
|
return ret;
|
|
}
|