docs/vm: hwpoison.txt: convert to ReST format

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mike Rapoport 2018-03-21 21:22:25 +02:00 committed by Jonathan Corbet
parent 88ececc23c
commit b53ba58845

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@ -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
=======
---
* madvise(MADV_HWPOISON, ....) (as root) - Poison a page in the
process for testing
Testing:
* hwpoison-inject module through debugfs ``/sys/kernel/debug/hwpoison/``
madvise(MADV_HWPOISON, ....)
(as root)
Poison a page in the process for testing
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.
hwpoison-inject module through debugfs
Note these injection interfaces are not stable and might change between
kernel versions
/sys/kernel/debug/hwpoison/
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-pfn
corrupt-filter-memcg
Limit injection to pages owned by memgroup. Specified by inode
number of the memcg.
Inject hwpoison fault at PFN echoed into this file. This does
some early filtering to avoid corrupted unintended pages in test suites.
Example::
unpoison-pfn
mkdir /sys/fs/cgroup/mem/hwpoison
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.
usemem -m 100 -s 1000 &
echo `jobs -p` > /sys/fs/cgroup/mem/hwpoison/tasks
Note these injection interfaces are not stable and might change between
kernel versions
memcg_ino=$(ls -id /sys/fs/cgroup/mem/hwpoison | cut -f1 -d' ')
echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
corrupt-filter-dev-major
corrupt-filter-dev-minor
page-types -p `pidof init` --hwpoison # shall do nothing
page-types -p `pidof usemem` --hwpoison # poison its pages
Only handle memory failures to pages associated with the file system defined
by block device major/minor. -1U is the wildcard value.
This should be only used for testing with artificial injection.
corrupt-filter-flags-mask, corrupt-filter-flags-value
When specified, only poison pages if ((page_flags & mask) ==
value). This allows stress testing of many kinds of
pages. The page_flags are the same as in /proc/kpageflags. The
flag bits are defined in include/linux/kernel-page-flags.h and
documented in Documentation/vm/pagemap.txt
corrupt-filter-memcg
* Architecture specific MCE injector
Limit injection to pages owned by memgroup. Specified by inode number
of the memcg.
x86 has mce-inject, mce-test
Example:
mkdir /sys/fs/cgroup/mem/hwpoison
Some portable hwpoison test programs in mce-test, see below.
usemem -m 100 -s 1000 &
echo `jobs -p` > /sys/fs/cgroup/mem/hwpoison/tasks
memcg_ino=$(ls -id /sys/fs/cgroup/mem/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
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