This is a simpler, gentler variant of memory_failure() for soft page
offlining controlled from user space.  It doesn't kill anything, just
tries to invalidate and if that doesn't work migrate the
page away.

This is useful for predictive failure analysis, where a page has
a high rate of corrected errors, but hasn't gone bad yet. Instead
it can be offlined early and avoided.

The offlining is controlled from sysfs, including a new generic
entry point for hard page offlining for symmetry too.

We use the page isolate facility to prevent re-allocation
race. Normally this is only used by memory hotplug. To avoid
races with memory allocation I am using lock_system_sleep().
This avoids the situation where memory hotplug is about
to isolate a page range and then hwpoison undoes that work.
This is a big hammer currently, but the simplest solution
currently.

When the page is not free or LRU we try to free pages
from slab and other caches. The slab freeing is currently
quite dumb and does not try to focus on the specific slab
cache which might own the page. This could be potentially
improved later.

Thanks to Fengguang Wu and Haicheng Li for some fixes.

[Added fix from Andrew Morton to adapt to new migrate_pages prototype]
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Signed-off-by: Andi Kleen <ak@linux.intel.com>

shake_page handles more types of page caches than
the much simpler lru_add_drain_all:

- slab (quite inefficiently for now)
- any other caches with a shrinker callback
- per cpu page allocator pages
- per CPU LRU

Use this call to try to turn pages into free or LRU pages.
Then handle the case of the page becoming free after drain everything.
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Signed-off-by: Andi Kleen <ak@linux.intel.com>

Signed-off-by: Andi Kleen <ak@linux.intel.com>

The previous version didn't take the mmap_sem before calling gup(),
which is racy.

Use get_user_pages_fast() instead which doesn't need any locks.
This is also faster of course, but then it doesn't really matter
because this is just a testing path.

Based on report from Nick Piggin.
Cc: npiggin@suse.de
Signed-off-by: Andi Kleen <ak@linux.intel.com>

In some use cases, user doesn't need extra filtering. E.g. user program
can inject errors through madvise syscall to its own pages, however it
might not know what the page state exactly is or which inode the page
belongs to.

So introduce an one-off interface "corrupt-filter-enable".

Echo 0 to switch off page filters, and echo 1 to switch on the filters.
[AK: changed default to 0]
Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

The hwpoison test suite need to inject hwpoison to a collection of
selected task pages, and must not touch pages not owned by them and
thus kill important system processes such as init. (But it's OK to
mis-hwpoison free/unowned pages as well as shared clean pages.
Mis-hwpoison of shared dirty pages will kill all tasks, so the test
suite will target all or non of such tasks in the first place.)

The memory cgroup serves this purpose well. We can put the target
processes under the control of a memory cgroup, and tell the hwpoison
injection code to only kill pages associated with some active memory
cgroup.

The prerequisite for doing hwpoison stress tests with mem_cgroup is,
the mem_cgroup code tracks task pages _accurately_ (unless page is
locked).  Which we believe is/should be true.

The benefits are simplification of hwpoison injector code. Also the
mem_cgroup code will automatically be tested by hwpoison test cases.

The alternative interfaces pin-pfn/unpin-pfn can also delegate the
(process and page flags) filtering functions reliably to user space.
However prototype implementation shows that this scheme adds more
complexity than we wanted.

Example test case:

	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

[AK: Fix documentation]
[Add fix for problem noticed by Li Zefan <lizf@cn.fujitsu.com>;
dentry in the css could be NULL]

CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Hugh Dickins <hugh.dickins@tiscali.co.uk>
CC: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
CC: Balbir Singh <balbir@linux.vnet.ibm.com>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Li Zefan <lizf@cn.fujitsu.com>
CC: Paul Menage <menage@google.com>
CC: Nick Piggin <npiggin@suse.de>
CC: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

So that an outside user can free the reference count grabbed by
try_get_mem_cgroup_from_page().

CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Hugh Dickins <hugh.dickins@tiscali.co.uk>
CC: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
CC: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

So that the hwpoison injector can get mem_cgroup for arbitrary page
and thus know whether it is owned by some mem_cgroup task(s).

[AK: Merged with latest git tree]

CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Hugh Dickins <hugh.dickins@tiscali.co.uk>
CC: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
CC: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

When specified, only poison pages if ((page_flags & mask) == value).

-       corrupt-filter-flags-mask
-       corrupt-filter-flags-value

This allows stress testing of many kinds of pages.

Strictly speaking, the buddy pages requires taking zone lock, to avoid
setting PG_hwpoison on a "was buddy but now allocated to someone" page.
However we can just do nothing because we set PG_locked in the beginning,
this prevents the page allocator from allocating it to someone. (It will
BUG() on the unexpected PG_locked, which is fine for hwpoison testing.)

[AK: Add select PROC_PAGE_MONITOR to satisfy dependency]

CC: Nick Piggin <npiggin@suse.de>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Rename get_uflags() to stable_page_flags() and make it a global function
for use in the hwpoison page flags filter, which need to compare user
page flags with the value provided by user space.

Also move KPF_* to kernel-page-flags.h for use by user space tools.
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
CC: Nick Piggin <npiggin@suse.de>
CC: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

__memory_failure()'s workflow is

	set PG_hwpoison
	//...
	unset PG_hwpoison if didn't pass hwpoison filter

That could kill unrelated process if it happens to page fault on the
page with the (temporary) PG_hwpoison. The race should be big enough to
appear in stress tests.

Fix it by grabbing the page and checking filter at inject time.  This
also avoids the very noisy "Injecting memory failure..." messages.

- we don't touch madvise() based injection, because the filters are
  generally not necessary for it.
- if we want to apply the filters to h/w aided injection, we'd better to
  rearrange the logic in __memory_failure() instead of this patch.

AK: fix documentation, use drain all, cleanups

CC: Haicheng Li <haicheng.li@intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Filesystem data/metadata present the most tricky-to-isolate pages.
It requires careful code review and stress testing to get them right.

The fs/device filter helps to target the stress tests to some specific
filesystem pages. The filter condition is block device's major/minor
numbers:
        - corrupt-filter-dev-major
        - corrupt-filter-dev-minor
When specified (non -1), only page cache pages that belong to that
device will be poisoned.

The filters are checked reliably on the locked and refcounted page.

Haicheng: clear PG_hwpoison and drop bad page count if filter not OK
AK: Add documentation

CC: Haicheng Li <haicheng.li@intel.com>
CC: Nick Piggin <npiggin@suse.de>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Return 0 to indicate success, when
- action result is RECOVERED or DELAYED
- no extra page reference

Note that dirty swapcache pages are kept in swapcache, so can have one
more reference count.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Change semantics for
- IGNORED: not handled; it may well be _unsafe_
- DELAYED: to be handled later; it is _safe_

With this change,
- IGNORED/FAILED mean (maybe) Error
- DELAYED/RECOVERED mean Success
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

The unpoisoning interface is useful for stress testing tools to
reclaim poisoned pages (to prevent OOM)

There is no hardware level unpoisioning, so this
cannot be used for real memory errors, only for software injected errors.

Note that it may leak pages silently - those who have been removed from
LRU cache, but not isolated from page cache/swap cache at hwpoison time.
Especially the stress test of dirty swap cache pages shall reboot system
before exhausting memory.

AK: Fix comments, add documentation, add printks, rename symbol
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Most free pages in the buddy system have no PG_buddy set.
Introduce is_free_buddy_page() for detecting them reliably.

CC: Nick Piggin <npiggin@suse.de>
CC: Mel Gorman <mel@linux.vnet.ibm.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

The buddy page has already be handled in the very beginning.
So remove redundant code.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Introduce delete_from_lru_cache() to
- clear PG_active, PG_unevictable to avoid complains at unpoison time
- move the isolate_lru_page() call back to the handlers instead of the
  entrance of __memory_failure(), this is more hwpoison filter friendly
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

AK: Improve comment
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Don't try to isolate a still mapped page. Otherwise we will hit the
BUG_ON(page_mapped(page)) in __remove_from_page_cache().
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Now that "ref" is just a boolean turn it into
a flags argument. First step is only a single flag
that makes the code's intention more clear, but more
may follow.
Signed-off-by: Andi Kleen <ak@linux.intel.com>

If page is double referenced in madvise_hwpoison() and __memory_failure(),
remove_mapping() will fail because it expects page_count=2. Fix it by
not grabbing extra page count in __memory_failure().
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Use a different errno than the usual EIO for invalid page numbers.
This is mainly for better reporting for the injector.

This also avoids calling action_result() with invalid pfn.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

(PG_swapbacked && !PG_lru) pages should not happen.
Better to treat them as unknown pages.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

shake_page handles more types of page caches than lru_drain_all()

- per cpu page allocator pages
- per CPU LRU

Stops early when the page became free.

Used in followon patches.
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Signed-off-by: Andi Kleen <ak@linux.intel.com>

Caused by commit 0b83ddeb ("MFD:
twl4030: add twl4030_codec MFD as a new child to the core") interacting
with commit b07682b6 ("mfd: Rename
twl4030* driver files to enable re-use").

This file seems to have been missed in the renaming.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://oss.sgi.com/xfs/xfs:
  xfs: event tracing support
  xfs: change the xfs_iext_insert / xfs_iext_remove
  xfs: cleanup bmap extent state macros

* git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: (80 commits)
  dm snapshot: use merge origin if snapshot invalid
  dm snapshot: report merge failure in status
  dm snapshot: merge consecutive chunks together
  dm snapshot: trigger exceptions in remaining snapshots during merge
  dm snapshot: delay merging a chunk until writes to it complete
  dm snapshot: queue writes to chunks being merged
  dm snapshot: add merging
  dm snapshot: permit only one merge at once
  dm snapshot: support barriers in snapshot merge target
  dm snapshot: avoid allocating exceptions in merge
  dm snapshot: rework writing to origin
  dm snapshot: add merge target
  dm exception store: add merge specific methods
  dm snapshot: create function for chunk_is_tracked wait
  dm snapshot: make bio optional in __origin_write
  dm mpath: reject messages when device is suspended
  dm: export suspended state to targets
  dm: rename dm_suspended to dm_suspended_md
  dm: swap target postsuspend call and setting suspended flag
  dm crypt: add plain64 iv
  ...

* 'for-2.6.33' of git://git.kernel.dk/linux-2.6-block:
  cfq: set workload as expired if it doesn't have any slice left
  Fix a CFQ crash in "for-2.6.33" branch of block tree
  cfq: Remove wait_request flag when idle time is being deleted
  cfq-iosched: commenting non-obvious initialization
  cfq-iosched: Take care of corner cases of group losing share due to deletion
  cfq-iosched: Get rid of cfqq wait_busy_done flag
  cfq: Optimization for close cooperating queue searching
  block,xd: Delay allocation of DMA buffers until device is known
  drbd: Following the hmac change to SHASH (see linux commit 8bd1209c)
  cfq-iosched: reduce write depth only if sync was delayed

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: ac97_codec - increase timeout for analog sections to 5 second
  ASoC: Correct code taking the size of a pointer
  ALSA: hda - Add PCI IDs for Nvidia G2xx-series
  ALSA: sound/isa/gus: Correct code taking the size of a pointer
  ALSA: hda: Fix max PCM level to 0 dB for AD1981_HP
  ALSA: hda: Use ALC260_WILL quirk for another Acer model (0x1025007f)

Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (26 commits)
  clockevents: Convert to raw_spinlock
  clockevents: Make tick_device_lock static
  debugobjects: Convert to raw_spinlocks
  perf_event: Convert to raw_spinlock
  hrtimers: Convert to raw_spinlocks
  genirq: Convert irq_desc.lock to raw_spinlock
  smp: Convert smplocks to raw_spinlocks
  rtmutes: Convert rtmutex.lock to raw_spinlock
  sched: Convert pi_lock to raw_spinlock
  sched: Convert cpupri lock to raw_spinlock
  sched: Convert rt_runtime_lock to raw_spinlock
  sched: Convert rq->lock to raw_spinlock
  plist: Make plist debugging raw_spinlock aware
  bkl: Fixup core_lock fallout
  locking: Cleanup the name space completely
  locking: Further name space cleanups
  alpha: Fix fallout from locking changes
  locking: Implement new raw_spinlock
  locking: Convert raw_rwlock functions to arch_rwlock
  locking: Convert raw_rwlock to arch_rwlock
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/hskinnemoen/avr32-2.6:
  avr32: update default configurations for ATNGW100, ATSTK1002 and ATSTK1006
  avr32: add default configurations for ATNGW100 mkII and EVKLCD10X
  avr32: add support for ATNGW100 mkII board
  avr32: convert to asm-generic/hardirq.h
  avr32: add two new at91 to cpu.h definition
  avr32: clean up linker script using standard macros.
  avr32: MRMT: correct setup of SPI slaves
  avr32: function for independently setting up SPI slaves
  avr32: re-instate MCI WP/CD pin assignments for ATNGW100

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc64: Fix clock event multiplier printf format.
  sparc64: Use clock{source,events}_calc_mult_shift().
  sparc64: Use free_bootmem_late() in mdesc_lmb_free().
  sparc: Add alignment and emulation fault perf events.
  sparc64: Add syscall tracepoint support.
  sparc: Stop trying to be so fancy and use __builtin_{memcpy,memset}()
  sparc: Use __builtin_object_size() to validate the buffer size for copy_from_user()
  sparc64: Add some missing __kprobes annotations to kernel fault paths.
  sparc64: Use kprobes_built_in() to avoid ifdefs in fault_64.c
  sparc: Validate that kprobe address is 4-byte aligned.
  sparc64: Don't specify IRQF_SHARED for LDC interrupts.
  sparc64: Fix stack debugging IRQ stack regression.
  sparc64: Fix overly strict range type matching for PCI devices.

* git://git.infradead.org/battery-2.6:
  power_supply_sysfs: Handle -ENODATA in a special way
  wm831x_backup: Remove unused variables
  gta02: Set pcf50633 charger_reference_current_ma
  pcf50633: Query charger status directly
  pcf50633: Properly reenable charging when the supply conditions change
  pcf50633: Get rid of charging restart software auto-triggering
  pcf50633: introduces battery charging current control
  pcf50633: Add ac power supply class to the charger
  wm831x: Factor out WM831x backup battery charger

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6:
  USB: Close usb_find_interface race v3
  Revert "USB: Close usb_find_interface race"