adulau/aha
1
0
Fork 0
mirror of https://github.com/adulau/aha.git synced 2024-12-27 03:06:10 +00:00
Code Issues Projects Releases Packages Wiki Activity

Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6

Browse source 
* 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: (34 commits)
  HWPOISON: Remove stray phrase in a comment
  HWPOISON: Try to allocate migration page on the same node
  HWPOISON: Don't do early filtering if filter is disabled
  HWPOISON: Add a madvise() injector for soft page offlining
  HWPOISON: Add soft page offline support
  HWPOISON: Undefine short-hand macros after use to avoid namespace conflict
  HWPOISON: Use new shake_page in memory_failure
  HWPOISON: Use correct name for MADV_HWPOISON in documentation
  HWPOISON: mention HWPoison in Kconfig entry
  HWPOISON: Use get_user_page_fast in hwpoison madvise
  HWPOISON: add an interface to switch off/on all the page filters
  HWPOISON: add memory cgroup filter
  memcg: add accessor to mem_cgroup.css
  memcg: rename and export try_get_mem_cgroup_from_page()
  HWPOISON: add page flags filter
  mm: export stable page flags
  HWPOISON: limit hwpoison injector to known page types
  HWPOISON: add fs/device filters
  HWPOISON: return 0 to indicate success reliably
  HWPOISON: make semantics of IGNORED/DELAYED clear
  ...
This commit is contained in:
Linus Torvalds 2009-12-16 12:36:49 -08:00
commit d4220f987c
19 changed files with 923 additions and 127 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

44
Documentation/ABI/testing/sysfs-memory-page-offline Normal file
View file

@ -0,0 +1,44 @@
What: /sys/devices/system/memory/soft_offline_page
Date: Sep 2009
KernelVersion: 2.6.33
Contact: andi@firstfloor.org
Description:
Soft-offline the memory page containing the physical address
written into this file. Input is a hex number specifying the
physical address of the page. The kernel will then attempt
to soft-offline it, by moving the contents elsewhere or
dropping it if possible. The kernel will then be placed
on the bad page list and never be reused.
The offlining is done in kernel specific granuality.
Normally it's the base page size of the kernel, but
this might change.
The page must be still accessible, not poisoned. The
kernel will never kill anything for this, but rather
fail the offline. Return value is the size of the
number, or a error when the offlining failed. Reading
the file is not allowed.
What: /sys/devices/system/memory/hard_offline_page
Date: Sep 2009
KernelVersion: 2.6.33
Contact: andi@firstfloor.org
Description:
Hard-offline the memory page containing the physical
address written into this file. Input is a hex number
specifying the physical address of the page. The
kernel will then attempt to hard-offline the page, by
trying to drop the page or killing any owner or
triggering IO errors if needed. Note this may kill
any processes owning the page. The kernel will avoid
to access this page assuming it's poisoned by the
hardware.
The offlining is done in kernel specific granuality.
Normally it's the base page size of the kernel, but
this might change.
Return value is the size of the number, or a error when
the offlining failed.
Reading the file is not allowed.

52
Documentation/vm/hwpoison.txt
View file

@ -92,16 +92,62 @@ PR_MCE_KILL_GET
Testing:
madvise(MADV_POISON, ....)
madvise(MADV_HWPOISON, ....)
(as root)
Poison a page in the process for testing
hwpoison-inject module through debugfs
/sys/debug/hwpoison/corrupt-pfn
Inject hwpoison fault at PFN echoed into this file
/sys/debug/hwpoison/
corrupt-pfn
Inject hwpoison fault at PFN echoed into this file. This does
some early filtering to avoid corrupted unintended pages in test suites.
unpoison-pfn
Software-unpoison page at PFN echoed into this file. This
way a page can be reused again.
This only works for Linux injected failures, not for real
memory failures.
Note these injection interfaces are not stable and might change between
kernel versions
corrupt-filter-dev-major
corrupt-filter-dev-minor
Only handle memory failures to pages associated with the file system defined
by block device major/minor. -1U is the wildcard value.
This should be only used for testing with artificial injection.
corrupt-filter-memcg
Limit injection to pages owned by memgroup. Specified by inode number
of the memcg.
Example:
mkdir /cgroup/hwpoison
usemem -m 100 -s 1000 &
echo `jobs -p` > /cgroup/hwpoison/tasks
memcg_ino=$(ls -id /cgroup/hwpoison | cut -f1 -d' ')
echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
page-types -p `pidof init` --hwpoison # shall do nothing
page-types -p `pidof usemem` --hwpoison # poison its pages
corrupt-filter-flags-mask
corrupt-filter-flags-value
When specified, only poison pages if ((page_flags & mask) == value).
This allows stress testing of many kinds of pages. The page_flags
are the same as in /proc/kpageflags. The flag bits are defined in
include/linux/kernel-page-flags.h and documented in
Documentation/vm/pagemap.txt
Architecture specific MCE injector

15
Documentation/vm/page-types.c
View file

@ -1,11 +1,22 @@
/*
* page-types: Tool for querying page flags
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; version 2.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should find a copy of v2 of the GNU General Public License somewhere on
* your Linux system; if not, write to the Free Software Foundation, Inc., 59
* Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*
* Copyright (C) 2009 Intel corporation
*
* Authors: Wu Fengguang <fengguang.wu@intel.com>
*
* Released under the General Public License (GPL).
*/
#define _LARGEFILE64_SOURCE

9
MAINTAINERS
View file

@ -2377,6 +2377,15 @@ W: http://www.kernel.org/pub/linux/kernel/people/fseidel/hdaps/
S: Maintained
F: drivers/hwmon/hdaps.c
HWPOISON MEMORY FAILURE HANDLING
M: Andi Kleen <andi@firstfloor.org>
L: linux-mm@kvack.org
L: linux-kernel@vger.kernel.org
T: git git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6.git hwpoison
S: Maintained
F: mm/memory-failure.c
F: mm/hwpoison-inject.c
HYPERVISOR VIRTUAL CONSOLE DRIVER
L: linuxppc-dev@ozlabs.org
S: Odd Fixes

61
drivers/base/memory.c
View file

@ -341,6 +341,64 @@ static inline int memory_probe_init(void)
}
#endif
#ifdef CONFIG_MEMORY_FAILURE
/*
* Support for offlining pages of memory
*/
/* Soft offline a page */
static ssize_t
store_soft_offline_page(struct class *class, const char *buf, size_t count)
{
int ret;
u64 pfn;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (strict_strtoull(buf, 0, &pfn) < 0)
return -EINVAL;
pfn >>= PAGE_SHIFT;
if (!pfn_valid(pfn))
return -ENXIO;
ret = soft_offline_page(pfn_to_page(pfn), 0);
return ret == 0 ? count : ret;
}
/* Forcibly offline a page, including killing processes. */
static ssize_t
store_hard_offline_page(struct class *class, const char *buf, size_t count)
{
int ret;
u64 pfn;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (strict_strtoull(buf, 0, &pfn) < 0)
return -EINVAL;
pfn >>= PAGE_SHIFT;
ret = __memory_failure(pfn, 0, 0);
return ret ? ret : count;
}
static CLASS_ATTR(soft_offline_page, 0644, NULL, store_soft_offline_page);
static CLASS_ATTR(hard_offline_page, 0644, NULL, store_hard_offline_page);
static __init int memory_fail_init(void)
{
int err;
err = sysfs_create_file(&memory_sysdev_class.kset.kobj,
&class_attr_soft_offline_page.attr);
if (!err)
err = sysfs_create_file(&memory_sysdev_class.kset.kobj,
&class_attr_hard_offline_page.attr);
return err;
}
#else
static inline int memory_fail_init(void)
{
return 0;
}
#endif
/*
* Note that phys_device is optional. It is here to allow for
* differentiation between which *physical* devices each
@ -471,6 +529,9 @@ int __init memory_dev_init(void)
}
err = memory_probe_init();
if (!ret)
ret = err;
err = memory_fail_init();
if (!ret)
ret = err;
err = block_size_init();

45
fs/proc/page.c
View file

@ -8,6 +8,7 @@
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/hugetlb.h>
#include <linux/kernel-page-flags.h>
#include <asm/uaccess.h>
#include "internal.h"
@ -71,52 +72,12 @@ static const struct file_operations proc_kpagecount_operations = {
* physical page flags.
*/
/* These macros are used to decouple internal flags from exported ones */
#define KPF_LOCKED 0
#define KPF_ERROR 1
#define KPF_REFERENCED 2
#define KPF_UPTODATE 3
#define KPF_DIRTY 4
#define KPF_LRU 5
#define KPF_ACTIVE 6
#define KPF_SLAB 7
#define KPF_WRITEBACK 8
#define KPF_RECLAIM 9
#define KPF_BUDDY 10
/* 11-20: new additions in 2.6.31 */
#define KPF_MMAP 11
#define KPF_ANON 12
#define KPF_SWAPCACHE 13
#define KPF_SWAPBACKED 14
#define KPF_COMPOUND_HEAD 15
#define KPF_COMPOUND_TAIL 16
#define KPF_HUGE 17
#define KPF_UNEVICTABLE 18
#define KPF_HWPOISON 19
#define KPF_NOPAGE 20
#define KPF_KSM 21
/* kernel hacking assistances
* WARNING: subject to change, never rely on them!
*/
#define KPF_RESERVED 32
#define KPF_MLOCKED 33
#define KPF_MAPPEDTODISK 34
#define KPF_PRIVATE 35
#define KPF_PRIVATE_2 36
#define KPF_OWNER_PRIVATE 37
#define KPF_ARCH 38
#define KPF_UNCACHED 39
static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
{
return ((kflags >> kbit) & 1) << ubit;
}
static u64 get_uflags(struct page *page)
u64 stable_page_flags(struct page *page)
{
u64 k;
u64 u;
@ -219,7 +180,7 @@ static ssize_t kpageflags_read(struct file *file, char __user *buf,
else
ppage = NULL;
if (put_user(get_uflags(ppage), out)) {
if (put_user(stable_page_flags(ppage), out)) {
ret = -EFAULT;
break;
}

1
include/asm-generic/mman-common.h
View file

@ -40,6 +40,7 @@
#define MADV_DONTFORK 10 /* don't inherit across fork */
#define MADV_DOFORK 11 /* do inherit across fork */
#define MADV_HWPOISON 100 /* poison a page for testing */
#define MADV_SOFT_OFFLINE 101 /* soft offline page for testing */
#define MADV_MERGEABLE 12 /* KSM may merge identical pages */
#define MADV_UNMERGEABLE 13 /* KSM may not merge identical pages */

46
include/linux/kernel-page-flags.h Normal file
View file

@ -0,0 +1,46 @@
#ifndef LINUX_KERNEL_PAGE_FLAGS_H
#define LINUX_KERNEL_PAGE_FLAGS_H
/*
* Stable page flag bits exported to user space
*/
#define KPF_LOCKED 0
#define KPF_ERROR 1
#define KPF_REFERENCED 2
#define KPF_UPTODATE 3
#define KPF_DIRTY 4
#define KPF_LRU 5
#define KPF_ACTIVE 6
#define KPF_SLAB 7
#define KPF_WRITEBACK 8
#define KPF_RECLAIM 9
#define KPF_BUDDY 10
/* 11-20: new additions in 2.6.31 */
#define KPF_MMAP 11
#define KPF_ANON 12
#define KPF_SWAPCACHE 13
#define KPF_SWAPBACKED 14
#define KPF_COMPOUND_HEAD 15
#define KPF_COMPOUND_TAIL 16
#define KPF_HUGE 17
#define KPF_UNEVICTABLE 18
#define KPF_HWPOISON 19
#define KPF_NOPAGE 20
#define KPF_KSM 21
/* kernel hacking assistances
* WARNING: subject to change, never rely on them!
*/
#define KPF_RESERVED 32
#define KPF_MLOCKED 33
#define KPF_MAPPEDTODISK 34
#define KPF_PRIVATE 35
#define KPF_PRIVATE_2 36
#define KPF_OWNER_PRIVATE 37
#define KPF_ARCH 38
#define KPF_UNCACHED 39
#endif /* LINUX_KERNEL_PAGE_FLAGS_H */

13
include/linux/memcontrol.h
View file

@ -73,6 +73,7 @@ extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
extern void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask);
int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);
extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
static inline
@ -85,6 +86,8 @@ int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
return cgroup == mem;
}
extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem);
extern int
mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr);
extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
@ -202,6 +205,11 @@ mem_cgroup_move_lists(struct page *page, enum lru_list from, enum lru_list to)
{
}
static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
{
return NULL;
}
static inline int mm_match_cgroup(struct mm_struct *mm, struct mem_cgroup *mem)
{
return 1;
@ -213,6 +221,11 @@ static inline int task_in_mem_cgroup(struct task_struct *task,
return 1;
}
static inline struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
{
return NULL;
}
static inline int
mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
{

8
include/linux/mm.h
View file

@ -1331,11 +1331,17 @@ extern int account_locked_memory(struct mm_struct *mm, struct rlimit *rlim,
size_t size);
extern void refund_locked_memory(struct mm_struct *mm, size_t size);
enum mf_flags {
MF_COUNT_INCREASED = 1 << 0,
};
extern void memory_failure(unsigned long pfn, int trapno);
extern int __memory_failure(unsigned long pfn, int trapno, int ref);
extern int __memory_failure(unsigned long pfn, int trapno, int flags);
extern int unpoison_memory(unsigned long pfn);
extern int sysctl_memory_failure_early_kill;
extern int sysctl_memory_failure_recovery;
extern void shake_page(struct page *p, int access);
extern atomic_long_t mce_bad_pages;
extern int soft_offline_page(struct page *page, int flags);
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */

4
include/linux/page-flags.h
View file

@ -275,13 +275,15 @@ PAGEFLAG_FALSE(Uncached)
#ifdef CONFIG_MEMORY_FAILURE
PAGEFLAG(HWPoison, hwpoison)
TESTSETFLAG(HWPoison, hwpoison)
TESTSCFLAG(HWPoison, hwpoison)
#define __PG_HWPOISON (1UL << PG_hwpoison)
#else
PAGEFLAG_FALSE(HWPoison)
#define __PG_HWPOISON 0
#endif
u64 stable_page_flags(struct page *page);
static inline int PageUptodate(struct page *page)
{
int ret = test_bit(PG_uptodate, &(page)->flags);

3
mm/Kconfig
View file

@ -251,8 +251,9 @@ config MEMORY_FAILURE
special hardware support and typically ECC memory.
config HWPOISON_INJECT
tristate "Poison pages injector"
tristate "HWPoison pages injector"
depends on MEMORY_FAILURE && DEBUG_KERNEL
select PROC_PAGE_MONITOR
config NOMMU_INITIAL_TRIM_EXCESS
int "Turn on mmap() excess space trimming before booting"

113
mm/hwpoison-inject.c
View file

@ -3,18 +3,68 @@
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include "internal.h"
static struct dentry *hwpoison_dir, *corrupt_pfn;
static struct dentry *hwpoison_dir;
static int hwpoison_inject(void *data, u64 val)
{
unsigned long pfn = val;
struct page *p;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
printk(KERN_INFO "Injecting memory failure at pfn %Lx\n", val);
return __memory_failure(val, 18, 0);
if (!hwpoison_filter_enable)
goto inject;
if (!pfn_valid(pfn))
return -ENXIO;
p = pfn_to_page(pfn);
/*
* This implies unable to support free buddy pages.
*/
if (!get_page_unless_zero(p))
return 0;
if (!PageLRU(p))
shake_page(p, 0);
/*
* This implies unable to support non-LRU pages.
*/
if (!PageLRU(p))
return 0;
/*
* do a racy check with elevated page count, to make sure PG_hwpoison
* will only be set for the targeted owner (or on a free page).
* We temporarily take page lock for try_get_mem_cgroup_from_page().
* __memory_failure() will redo the check reliably inside page lock.
*/
lock_page(p);
err = hwpoison_filter(p);
unlock_page(p);
if (err)
return 0;
inject:
printk(KERN_INFO "Injecting memory failure at pfn %lx\n", pfn);
return __memory_failure(pfn, 18, MF_COUNT_INCREASED);
}
static int hwpoison_unpoison(void *data, u64 val)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return unpoison_memory(val);
}
DEFINE_SIMPLE_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
DEFINE_SIMPLE_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");
static void pfn_inject_exit(void)
{
@ -24,16 +74,63 @@ static void pfn_inject_exit(void)
static int pfn_inject_init(void)
{
struct dentry *dentry;
hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
if (hwpoison_dir == NULL)
return -ENOMEM;
corrupt_pfn = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
/*
* Note that the below poison/unpoison interfaces do not involve
* hardware status change, hence do not require hardware support.
* They are mainly for testing hwpoison in software level.
*/
dentry = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
NULL, &hwpoison_fops);
if (corrupt_pfn == NULL) {
pfn_inject_exit();
return -ENOMEM;
}
if (!dentry)
goto fail;
dentry = debugfs_create_file("unpoison-pfn", 0600, hwpoison_dir,
NULL, &unpoison_fops);
if (!dentry)
goto fail;
dentry = debugfs_create_u32("corrupt-filter-enable", 0600,
hwpoison_dir, &hwpoison_filter_enable);
if (!dentry)
goto fail;
dentry = debugfs_create_u32("corrupt-filter-dev-major", 0600,
hwpoison_dir, &hwpoison_filter_dev_major);
if (!dentry)
goto fail;
dentry = debugfs_create_u32("corrupt-filter-dev-minor", 0600,
hwpoison_dir, &hwpoison_filter_dev_minor);
if (!dentry)
goto fail;
dentry = debugfs_create_u64("corrupt-filter-flags-mask", 0600,
hwpoison_dir, &hwpoison_filter_flags_mask);
if (!dentry)
goto fail;
dentry = debugfs_create_u64("corrupt-filter-flags-value", 0600,
hwpoison_dir, &hwpoison_filter_flags_value);
if (!dentry)
goto fail;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
hwpoison_dir, &hwpoison_filter_memcg);
if (!dentry)
goto fail;
#endif
return 0;
fail:
pfn_inject_exit();
return -ENOMEM;
}
module_init(pfn_inject_init);

12
mm/internal.h
View file

@ -50,6 +50,9 @@ extern void putback_lru_page(struct page *page);
*/
extern void __free_pages_bootmem(struct page *page, unsigned int order);
extern void prep_compound_page(struct page *page, unsigned long order);
#ifdef CONFIG_MEMORY_FAILURE
extern bool is_free_buddy_page(struct page *page);
#endif
/*
@ -247,3 +250,12 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
#define ZONE_RECLAIM_SOME 0
#define ZONE_RECLAIM_SUCCESS 1
#endif
extern int hwpoison_filter(struct page *p);
extern u32 hwpoison_filter_dev_major;
extern u32 hwpoison_filter_dev_minor;
extern u64 hwpoison_filter_flags_mask;
extern u64 hwpoison_filter_flags_value;
extern u64 hwpoison_filter_memcg;
extern u32 hwpoison_filter_enable;

21
mm/madvise.c
View file

@ -9,6 +9,7 @@
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/mempolicy.h>
#include <linux/page-isolation.h>
#include <linux/hugetlb.h>
#include <linux/sched.h>
#include <linux/ksm.h>
@ -222,7 +223,7 @@ static long madvise_remove(struct vm_area_struct *vma,
/*
* Error injection support for memory error handling.
*/
static int madvise_hwpoison(unsigned long start, unsigned long end)
static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
{
int ret = 0;
@ -230,15 +231,21 @@ static int madvise_hwpoison(unsigned long start, unsigned long end)
return -EPERM;
for (; start < end; start += PAGE_SIZE) {
struct page *p;
int ret = get_user_pages(current, current->mm, start, 1,
0, 0, &p, NULL);
int ret = get_user_pages_fast(start, 1, 0, &p);
if (ret != 1)
return ret;
if (bhv == MADV_SOFT_OFFLINE) {
printk(KERN_INFO "Soft offlining page %lx at %lx\n",
page_to_pfn(p), start);
ret = soft_offline_page(p, MF_COUNT_INCREASED);
if (ret)
break;
continue;
}
printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n",
page_to_pfn(p), start);
/* Ignore return value for now */
__memory_failure(page_to_pfn(p), 0, 1);
put_page(p);
__memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
}
return ret;
}
@ -335,8 +342,8 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
size_t len;
#ifdef CONFIG_MEMORY_FAILURE
if (behavior == MADV_HWPOISON)
return madvise_hwpoison(start, start+len_in);
if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
return madvise_hwpoison(behavior, start, start+len_in);
#endif
if (!madvise_behavior_valid(behavior))
return error;

16
mm/memcontrol.c
View file

@ -283,6 +283,11 @@ mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
return &mem->info.nodeinfo[nid]->zoneinfo[zid];
}
struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
{
return &mem->css;
}
static struct mem_cgroup_per_zone *
page_cgroup_zoneinfo(struct page_cgroup *pc)
{
@ -1536,25 +1541,22 @@ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
return container_of(css, struct mem_cgroup, css);
}
static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
{
struct mem_cgroup *mem;
struct mem_cgroup *mem = NULL;
struct page_cgroup *pc;
unsigned short id;
swp_entry_t ent;
VM_BUG_ON(!PageLocked(page));
if (!PageSwapCache(page))
return NULL;
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
mem = pc->mem_cgroup;
if (mem && !css_tryget(&mem->css))
mem = NULL;
} else {
} else if (PageSwapCache(page)) {
ent.val = page_private(page);
id = lookup_swap_cgroup(ent);
rcu_read_lock();
@ -1874,7 +1876,7 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
*/
if (!PageSwapCache(page))
goto charge_cur_mm;
mem = try_get_mem_cgroup_from_swapcache(page);
mem = try_get_mem_cgroup_from_page(page);
if (!mem)
goto charge_cur_mm;
*ptr = mem;

562
mm/memory-failure.c
View file

@ -34,12 +34,16 @@
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
#include <linux/kernel-page-flags.h>
#include <linux/sched.h>
#include <linux/ksm.h>
#include <linux/rmap.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/backing-dev.h>
#include <linux/migrate.h>
#include <linux/page-isolation.h>
#include <linux/suspend.h>
#include "internal.h"
int sysctl_memory_failure_early_kill __read_mostly = 0;
@ -48,6 +52,120 @@ int sysctl_memory_failure_recovery __read_mostly = 1;
atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);
u32 hwpoison_filter_enable = 0;
u32 hwpoison_filter_dev_major = ~0U;
u32 hwpoison_filter_dev_minor = ~0U;
u64 hwpoison_filter_flags_mask;
u64 hwpoison_filter_flags_value;
EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
static int hwpoison_filter_dev(struct page *p)
{
struct address_space *mapping;
dev_t dev;
if (hwpoison_filter_dev_major == ~0U &&
hwpoison_filter_dev_minor == ~0U)
return 0;
/*
* page_mapping() does not accept slab page
*/
if (PageSlab(p))
return -EINVAL;
mapping = page_mapping(p);
if (mapping == NULL || mapping->host == NULL)
return -EINVAL;
dev = mapping->host->i_sb->s_dev;
if (hwpoison_filter_dev_major != ~0U &&
hwpoison_filter_dev_major != MAJOR(dev))
return -EINVAL;
if (hwpoison_filter_dev_minor != ~0U &&
hwpoison_filter_dev_minor != MINOR(dev))
return -EINVAL;
return 0;
}
static int hwpoison_filter_flags(struct page *p)
{
if (!hwpoison_filter_flags_mask)
return 0;
if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
hwpoison_filter_flags_value)
return 0;
else
return -EINVAL;
}
/*
* This allows stress tests to limit test scope to a collection of tasks
* by putting them under some memcg. This prevents killing unrelated/important
* processes such as /sbin/init. Note that the target task may share clean
* pages with init (eg. libc text), which is harmless. If the target task
* share _dirty_ pages with another task B, the test scheme must make sure B
* is also included in the memcg. At last, due to race conditions this filter
* can only guarantee that the page either belongs to the memcg tasks, or is
* a freed page.
*/
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
u64 hwpoison_filter_memcg;
EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
static int hwpoison_filter_task(struct page *p)
{
struct mem_cgroup *mem;
struct cgroup_subsys_state *css;
unsigned long ino;
if (!hwpoison_filter_memcg)
return 0;
mem = try_get_mem_cgroup_from_page(p);
if (!mem)
return -EINVAL;
css = mem_cgroup_css(mem);
/* root_mem_cgroup has NULL dentries */
if (!css->cgroup->dentry)
return -EINVAL;
ino = css->cgroup->dentry->d_inode->i_ino;
css_put(css);
if (ino != hwpoison_filter_memcg)
return -EINVAL;
return 0;
}
#else
static int hwpoison_filter_task(struct page *p) { return 0; }
#endif
int hwpoison_filter(struct page *p)
{
if (!hwpoison_filter_enable)
return 0;
if (hwpoison_filter_dev(p))
return -EINVAL;
if (hwpoison_filter_flags(p))
return -EINVAL;
if (hwpoison_filter_task(p))
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(hwpoison_filter);
/*
* Send all the processes who have the page mapped an ``action optional''
* signal.
@ -82,6 +200,36 @@ static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
return ret;
}
/*
* When a unknown page type is encountered drain as many buffers as possible
* in the hope to turn the page into a LRU or free page, which we can handle.
*/
void shake_page(struct page *p, int access)
{
if (!PageSlab(p)) {
lru_add_drain_all();
if (PageLRU(p))
return;
drain_all_pages();
if (PageLRU(p) || is_free_buddy_page(p))
return;
}
/*
* Only all shrink_slab here (which would also
* shrink other caches) if access is not potentially fatal.
*/
if (access) {
int nr;
do {
nr = shrink_slab(1000, GFP_KERNEL, 1000);
if (page_count(p) == 0)
break;
} while (nr > 10);
}
}
EXPORT_SYMBOL_GPL(shake_page);
/*
* Kill all processes that have a poisoned page mapped and then isolate
* the page.
@ -177,7 +325,6 @@ static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
* In case something went wrong with munmapping
* make sure the process doesn't catch the
* signal and then access the memory. Just kill it.
* the signal handlers
*/
if (fail || tk->addr_valid == 0) {
printk(KERN_ERR
@ -314,33 +461,49 @@ static void collect_procs(struct page *page, struct list_head *tokill)
*/
enum outcome {
FAILED, /* Error handling failed */
IGNORED, /* Error: cannot be handled */
FAILED, /* Error: handling failed */
DELAYED, /* Will be handled later */
IGNORED, /* Error safely ignored */
RECOVERED, /* Successfully recovered */
};
static const char *action_name[] = {
[IGNORED] = "Ignored",
[FAILED] = "Failed",
[DELAYED] = "Delayed",
[IGNORED] = "Ignored",
[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 DELAYED;
}
/*
* Already poisoned page.
*/
static int me_ignore(struct page *p, unsigned long pfn)
{
return IGNORED;
}
@ -354,14 +517,6 @@ static int me_unknown(struct page *p, unsigned long pfn)
return FAILED;
}
/*
* Free memory
*/
static int me_free(struct page *p, unsigned long pfn)
{
return DELAYED;
}
/*
* Clean (or cleaned) page cache page.
*/
@ -371,6 +526,8 @@ static int me_pagecache_clean(struct page *p, unsigned long pfn)
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.
@ -500,14 +657,20 @@ static int me_swapcache_dirty(struct page *p, unsigned long pfn)
/* Trigger EIO in shmem: */
ClearPageUptodate(p);
return DELAYED;
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);
return RECOVERED;
if (!delete_from_lru_cache(p))
return RECOVERED;
else
return FAILED;
}
/*
@ -550,7 +713,6 @@ static int me_huge_page(struct page *p, unsigned long pfn)
#define tail (1UL << PG_tail)
#define compound (1UL << PG_compound)
#define slab (1UL << PG_slab)
#define buddy (1UL << PG_buddy)
#define reserved (1UL << PG_reserved)
static struct page_state {
@ -559,8 +721,11 @@ static struct page_state {
char *msg;
int (*action)(struct page *p, unsigned long pfn);
} error_states[] = {
{ reserved, reserved, "reserved kernel", me_ignore },
{ buddy, buddy, "free kernel", me_free },
{ 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
@ -587,7 +752,6 @@ static struct page_state {
{ lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
{ lru|dirty, lru, "clean LRU", me_pagecache_clean },
{ swapbacked, swapbacked, "anonymous", me_pagecache_clean },
/*
* Catchall entry: must be at end.
@ -595,20 +759,31 @@ static struct page_state {
{ 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 = NULL;
if (pfn_valid(pfn))
page = pfn_to_page(pfn);
struct page *page = pfn_to_page(pfn);
printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
pfn,
page && PageDirty(page) ? "dirty " : "",
PageDirty(page) ? "dirty " : "",
msg, action_name[result]);
}
static int page_action(struct page_state *ps, struct page *p,
unsigned long pfn, int ref)
unsigned long pfn)
{
int result;
int count;
@ -616,18 +791,22 @@ static int page_action(struct page_state *ps, struct page *p,
result = ps->action(p, pfn);
action_result(pfn, ps->msg, result);
count = page_count(p) - 1 - ref;
if (count != 0)
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 ? 0 : -EBUSY;
return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
}
#define N_UNMAP_TRIES 5
@ -636,7 +815,7 @@ static int page_action(struct page_state *ps, struct page *p,
* 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 void hwpoison_user_mappings(struct page *p, unsigned long pfn,
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;
@ -646,15 +825,18 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
int i;
int kill = 1;
if (PageReserved(p) || PageCompound(p) || PageSlab(p) || PageKsm(p))
return;
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(p))
return;
return SWAP_SUCCESS;
if (PageCompound(p) || PageKsm(p))
return SWAP_FAIL;
if (PageSwapCache(p)) {
printk(KERN_ERR
@ -665,6 +847,8 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
/*
* 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(p);
if (!PageDirty(p) && mapping && mapping_cap_writeback_dirty(mapping)) {
@ -716,11 +900,12 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
*/
kill_procs_ao(&tokill, !!PageDirty(p), trapno,
ret != SWAP_SUCCESS, pfn);
return ret;
}
int __memory_failure(unsigned long pfn, int trapno, int ref)
int __memory_failure(unsigned long pfn, int trapno, int flags)
{
unsigned long lru_flag;
struct page_state *ps;
struct page *p;
int res;
@ -729,13 +914,15 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
panic("Memory failure from trap %d on page %lx", trapno, pfn);
if (!pfn_valid(pfn)) {
action_result(pfn, "memory outside kernel control", IGNORED);
return -EIO;
printk(KERN_ERR
"MCE %#lx: memory outside kernel control\n",
pfn);
return -ENXIO;
}
p = pfn_to_page(pfn);
if (TestSetPageHWPoison(p)) {
action_result(pfn, "already hardware poisoned", IGNORED);
printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
return 0;
}
@ -752,9 +939,15 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
* In fact it's dangerous to directly bump up page count from 0,
* that may make page_freeze_refs()/page_unfreeze_refs() mismatch.
*/
if (!get_page_unless_zero(compound_head(p))) {
action_result(pfn, "free or high order kernel", IGNORED);
return PageBuddy(compound_head(p)) ? 0 : -EBUSY;
if (!(flags & MF_COUNT_INCREASED) &&
!get_page_unless_zero(compound_head(p))) {
if (is_free_buddy_page(p)) {
action_result(pfn, "free buddy", DELAYED);
return 0;
} else {
action_result(pfn, "high order kernel", IGNORED);
return -EBUSY;
}
}
/*
@ -766,14 +959,19 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
* walked by the page reclaim code, however that's not a big loss.
*/
if (!PageLRU(p))
lru_add_drain_all();
lru_flag = p->flags & lru;
if (isolate_lru_page(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;
}
page_cache_release(p);
/*
* Lock the page and wait for writeback to finish.
@ -781,26 +979,48 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
* and in many cases impossible, so we just avoid it here.
*/
lock_page_nosync(p);
/*
* 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_dec(&mce_bad_pages);
unlock_page(p);
put_page(p);
return 0;
}
wait_on_page_writeback(p);
/*
* Now take care of user space mappings.
* Abort on fail: __remove_from_page_cache() assumes unmapped page.
*/
hwpoison_user_mappings(p, pfn, trapno);
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 ((lru_flag & lru) && !PageSwapCache(p) && p->mapping == NULL) {
if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
action_result(pfn, "already truncated LRU", IGNORED);
res = 0;
res = -EBUSY;
goto out;
}
res = -EBUSY;
for (ps = error_states;; ps++) {
if (((p->flags | lru_flag)& ps->mask) == ps->res) {
res = page_action(ps, p, pfn, ref);
if ((p->flags & ps->mask) == ps->res) {
res = page_action(ps, p, pfn);
break;
}
}
@ -831,3 +1051,235 @@ 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;
if (!pfn_valid(pfn))
return -ENXIO;
p = pfn_to_page(pfn);
page = compound_head(p);
if (!PageHWPoison(p)) {
pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn);
return 0;
}
if (!get_page_unless_zero(page)) {
if (TestClearPageHWPoison(p))
atomic_long_dec(&mce_bad_pages);
pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn);
return 0;
}
lock_page_nosync(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(p)) {
pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn);
atomic_long_dec(&mce_bad_pages);
freeit = 1;
}
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);
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_system_sleep prevents a race with memory hotplug,
* because the isolation assumes there's only a single user.
* This is a big hammer, a better would be nicer.
*/
lock_system_sleep();
/*
* Isolate the page, so that it doesn't get reallocated if it
* was free.
*/
set_migratetype_isolate(p);
if (!get_page_unless_zero(compound_head(p))) {
if (is_free_buddy_page(p)) {
pr_debug("get_any_page: %#lx free buddy page\n", pfn);
/* Set hwpoison bit while page is still isolated */
SetPageHWPoison(p);
ret = 0;
} else {
pr_debug("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_system_sleep();
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);
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_debug("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_debug("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_debug("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);
if (ret) {
pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
pfn, ret, page->flags);
if (ret > 0)
ret = -EIO;
}
} else {
pr_debug("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;
}

4
mm/memory.c
View file

@ -2555,6 +2555,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
ret = VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
} else if (PageHWPoison(page)) {
/*
* hwpoisoned dirty swapcache pages are kept for killing
* owner processes (which may be unknown at hwpoison time)
*/
ret = VM_FAULT_HWPOISON;
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
goto out_release;

21
mm/page_alloc.c
View file

@ -5091,3 +5091,24 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
spin_unlock_irqrestore(&zone->lock, flags);
}
#endif
#ifdef CONFIG_MEMORY_FAILURE
bool is_free_buddy_page(struct page *page)
{
struct zone *zone = page_zone(page);
unsigned long pfn = page_to_pfn(page);
unsigned long flags;
int order;
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) {
struct page *page_head = page - (pfn & ((1 << order) - 1));
if (PageBuddy(page_head) && page_order(page_head) >= order)
break;
}
spin_unlock_irqrestore(&zone->lock, flags);
return order < MAX_ORDER;
}
#endif