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Subject[PATCH] [15/15] HWPOISON: Add simple debugfs interface to inject hwpoison on arbitary PFNs
Date

Useful for some testing scenarios, although specific testing is often
done better through MADV_POISON

This can be done with the x86 level MCE injector too, but this interface
allows it to do independently from low level x86 changes.

Open issues:

Should be disabled for cgroups.

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

---
mm/Kconfig | 6 +++++-
mm/Makefile | 1 +
mm/hwpoison-inject.c | 41 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 47 insertions(+), 1 deletion(-)
Index: linux/mm/hwpoison-inject.c
===================================================================
--- /dev/null
+++ linux/mm/hwpoison-inject.c
@@ -0,0 +1,41 @@
+/* Inject a hwpoison memory failure on a arbitary pfn */
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+
+static struct dentry *hwpoison_dir, *corrupt_pfn;
+
+static int hwpoison_inject(void *data, u64 val)
+{
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ printk(KERN_INFO "Injecting memory failure at pfn %Lx\n", val);
+ memory_failure(val, 18);
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
+
+static void pfn_inject_exit(void)
+{
+ if (hwpoison_dir)
+ debugfs_remove_recursive(hwpoison_dir);
+}
+
+static int pfn_inject_init(void)
+{
+ hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
+ if (hwpoison_dir == NULL)
+ return -ENOMEM;
+ corrupt_pfn = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
+ NULL, &hwpoison_fops);
+ if (corrupt_pfn == NULL) {
+ pfn_inject_exit();
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+module_init(pfn_inject_init);
+module_exit(pfn_inject_exit);
Index: linux/mm/Kconfig
===================================================================
--- linux.orig/mm/Kconfig
+++ linux/mm/Kconfig
@@ -236,12 +236,16 @@ config DEFAULT_MMAP_MIN_ADDR
config MEMORY_FAILURE
depends on MMU
depends on X86_MCE
- bool "Enable memory failure recovery"
+ bool "Enable recovery from hardware memory errors"
help
Enables code to recover from some memory failures on systems
with MCA recovery. This allows a system to continue running
even when some of its memory has uncorrected errors.

+config HWPOISON_INJECT
+ tristate "Poison pages injector"
+ depends on MEMORY_FAILURE && DEBUG_KERNEL
+
config NOMMU_INITIAL_TRIM_EXCESS
int "Turn on mmap() excess space trimming before booting"
depends on !MMU
Index: linux/mm/Makefile
===================================================================
--- linux.orig/mm/Makefile
+++ linux/mm/Makefile
@@ -41,5 +41,6 @@ endif
obj-$(CONFIG_QUICKLIST) += quicklist.o
obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
+obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o

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