@@ -1,7 +1,14 @@
+.. hwpoison:
+
+========
+hwpoison
+========
+
What is hwpoison?
+=================
Upcoming Intel CPUs have support for recovering from some memory errors
-(``MCA recovery''). This requires the OS to declare a page "poisoned",
+(``MCA recovery``). This requires the OS to declare a page "poisoned",
kill the processes associated with it and avoid using it in the future.
This patchkit implements the necessary infrastructure in the VM.
@@ -46,9 +53,10 @@ address. This in theory allows other applications to handle
memory failures too. The expection is that near all applications
won't do that, but some very specialized ones might.
----
+Failure recovery modes
+======================
-There are two (actually three) modi memory failure recovery can be in:
+There are two (actually three) modes memory failure recovery can be in:
vm.memory_failure_recovery sysctl set to zero:
All memory failures cause a panic. Do not attempt recovery.
@@ -67,9 +75,8 @@ late kill
This is best for memory error unaware applications and default
Note some pages are always handled as late kill.
----
-
-User control:
+User control
+============
vm.memory_failure_recovery
See sysctl.txt
@@ -79,11 +86,19 @@ vm.memory_failure_early_kill
PR_MCE_KILL
Set early/late kill mode/revert to system default
- arg1: PR_MCE_KILL_CLEAR: Revert to system default
- arg1: PR_MCE_KILL_SET: arg2 defines thread specific mode
- PR_MCE_KILL_EARLY: Early kill
- PR_MCE_KILL_LATE: Late kill
- PR_MCE_KILL_DEFAULT: Use system global default
+
+ arg1: PR_MCE_KILL_CLEAR:
+ Revert to system default
+ arg1: PR_MCE_KILL_SET:
+ arg2 defines thread specific mode
+
+ PR_MCE_KILL_EARLY:
+ Early kill
+ PR_MCE_KILL_LATE:
+ Late kill
+ PR_MCE_KILL_DEFAULT
+ Use system global default
+
Note that if you want to have a dedicated thread which handles
the SIGBUS(BUS_MCEERR_AO) on behalf of the process, you should
call prctl(PR_MCE_KILL_EARLY) on the designated thread. Otherwise,
@@ -92,77 +107,64 @@ PR_MCE_KILL
PR_MCE_KILL_GET
return current mode
+Testing
+=======
----
-
-Testing:
-
-madvise(MADV_HWPOISON, ....)
- (as root)
- Poison a page in the process for testing
-
+* madvise(MADV_HWPOISON, ....) (as root) - Poison a page in the
+ process for testing
-hwpoison-inject module through debugfs
+* hwpoison-inject module through debugfs ``/sys/kernel/debug/hwpoison/``
-/sys/kernel/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.
-corrupt-pfn
+ 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.
-Inject hwpoison fault at PFN echoed into this file. This does
-some early filtering to avoid corrupted unintended pages in test suites.
+ Note these injection interfaces are not stable and might change between
+ kernel versions
-unpoison-pfn
+ 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.
-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.
+ corrupt-filter-memcg
+ Limit injection to pages owned by memgroup. Specified by inode
+ number of the memcg.
-Note these injection interfaces are not stable and might change between
-kernel versions
+ Example::
-corrupt-filter-dev-major
-corrupt-filter-dev-minor
+ mkdir /sys/fs/cgroup/mem/hwpoison
-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.
+ usemem -m 100 -s 1000 &
+ echo `jobs -p` > /sys/fs/cgroup/mem/hwpoison/tasks
-corrupt-filter-memcg
+ memcg_ino=$(ls -id /sys/fs/cgroup/mem/hwpoison | cut -f1 -d' ')
+ echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
-Limit injection to pages owned by memgroup. Specified by inode number
-of the memcg.
+ page-types -p `pidof init` --hwpoison # shall do nothing
+ page-types -p `pidof usemem` --hwpoison # poison its pages
-Example:
- mkdir /sys/fs/cgroup/mem/hwpoison
+ corrupt-filter-flags-mask, corrupt-filter-flags-value
+ When specified, only poison pages if ((page_flags & mask) ==
+ value). This allows stress testing of many kinds of
+ pages. The page_flags are the same as in /proc/kpageflags. The
+ flag bits are defined in include/linux/kernel-page-flags.h and
+ documented in Documentation/vm/pagemap.txt
- usemem -m 100 -s 1000 &
- echo `jobs -p` > /sys/fs/cgroup/mem/hwpoison/tasks
+* Architecture specific MCE injector
- memcg_ino=$(ls -id /sys/fs/cgroup/mem/hwpoison | cut -f1 -d' ')
- echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
+ x86 has mce-inject, mce-test
- page-types -p `pidof init` --hwpoison # shall do nothing
- page-types -p `pidof usemem` --hwpoison # poison its pages
+ Some portable hwpoison test programs in mce-test, see below.
-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
-
-x86 has mce-inject, mce-test
-
-Some portable hwpoison test programs in mce-test, see blow.
-
----
-
-References:
+References
+==========
http://halobates.de/mce-lc09-2.pdf
Overview presentation from LinuxCon 09
@@ -174,14 +176,11 @@ git://git.kernel.org/pub/scm/utils/cpu/mce/mce-inject.git
x86 specific injector
----
-
-Limitations:
-
+Limitations
+===========
- Not all page types are supported and never will. Most kernel internal
-objects cannot be recovered, only LRU pages for now.
+ objects cannot be recovered, only LRU pages for now.
- Right now hugepage support is missing.
---
Andi Kleen, Oct 2009
-
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> --- Documentation/vm/hwpoison.txt | 141 +++++++++++++++++++++--------------------- 1 file changed, 70 insertions(+), 71 deletions(-)