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>
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>
__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>
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>
Now that ksm pages are swappable, and the known holes plugged, remove
mention of unswappable kernel pages from KSM documentation and comments.
Remove the totalram_pages/4 initialization of max_kernel_pages. In fact,
remove max_kernel_pages altogether - we can reinstate it if removal turns
out to break someone's script; but if we later want to limit KSM's memory
usage, limiting the stable nodes would not be an effective approach.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wright <chrisw@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On a system with large amount of memory (256GB), invoking page-types can
take quite a long time, which is unreasonable considering the user only
wants a description of the flags:
# time ./page-types -d 0x10
0x0000000000000010 ____D_____________________________ dirty
real 0m34.285s
user 0m1.966s
sys 0m32.313s
This is because we still walk the entire address range.
Exiting early seems like a reasonble solution:
# time ./page-types -d 0x10
0x0000000000000010 ____D_____________________________ dirty
real 0m0.007s
user 0m0.001s
sys 0m0.005s
Signed-off-by: Alex Chiang <achiang@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Haicheng Li <haicheng.li@intel.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Teach page-types to describe page flags directly from the command line.
Why is this useful? For instance, if you're using memory hotplug and see
this in /var/log/messages:
kernel: removing from LRU failed 3836dd0/1/1e00000000000010
It would be nice to decode those page flags without staring at the source.
Example usage and output:
# Documentation/vm/page-types -d 0x10
0x0000000000000010 ____D_____________________________ dirty
# Documentation/vm/page-types -d anon
0x0000000000001000 ____________a_____________________ anonymous
# Documentation/vm/page-types -d anon,0x10
0x0000000000001010 ____D_______a_____________________ dirty,anonymous
[achiang@hp.com: documentation]
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Haicheng Li <haicheng.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'hostprogs-wmissing-prototypes' of git://git.kernel.org/pub/scm/linux/kernel/git/josh/linux-misc:
Makefile: Add -Wmising-prototypes to HOSTCFLAGS
oss: Mark loadhex static in hex2hex.c
dtc: Mark various internal functions static
dtc: Set "noinput" in the lexer to avoid an unused function
drm: radeon: Mark several functions static in mkregtable
arch/sparc/boot/*.c: Mark various internal functions static
arch/powerpc/boot/addRamDisk.c: Mark several internal functions static
arch/alpha/boot/tools/objstrip.c: Mark "usage" static
Documentation/vm/page-types.c: Declare checked_open static
genksyms: Mark is_reserved_word static
kconfig: Mark various internal functions static
kconfig: Make zconf.y work with current bison
* 'hwpoison-2.6.32' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6:
HWPOISON: fix invalid page count in printk output
HWPOISON: Allow schedule_on_each_cpu() from keventd
HWPOISON: fix/proc/meminfo alignment
HWPOISON: fix oops on ksm pages
HWPOISON: Fix page count leak in hwpoison late kill in do_swap_page
HWPOISON: return early on non-LRU pages
HWPOISON: Add brief hwpoison description to Documentation
HWPOISON: Clean up PR_MCE_KILL interface
