[PATCH] fault-injection capability for alloc_pages()
This patch provides fault-injection capability for alloc_pages()
Boot option:
fail_page_alloc=<interval>,<probability>,<space>,<times>
<interval> -- specifies the interval of failures.
<probability> -- specifies how often it should fail in percent.
<space> -- specifies the size of free space where memory can be
allocated safely in pages.
<times> -- specifies how many times failures may happen at most.
Debugfs:
/debug/fail_page_alloc/interval
/debug/fail_page_alloc/probability
/debug/fail_page_alloc/specifies
/debug/fail_page_alloc/times
/debug/fail_page_alloc/ignore-gfp-highmem
/debug/fail_page_alloc/ignore-gfp-wait
Example:
fail_page_alloc=10,100,0,-1
The page allocation (alloc_pages(), ...) fails once per 10 times.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 18f0e04..0cc8b43 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -40,6 +40,7 @@
#include <linux/sort.h>
#include <linux/pfn.h>
#include <linux/backing-dev.h>
+#include <linux/fault-inject.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -892,6 +893,89 @@
#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
+#ifdef CONFIG_FAIL_PAGE_ALLOC
+
+static struct fail_page_alloc_attr {
+ struct fault_attr attr;
+
+ u32 ignore_gfp_highmem;
+ u32 ignore_gfp_wait;
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+ struct dentry *ignore_gfp_highmem_file;
+ struct dentry *ignore_gfp_wait_file;
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
+
+} fail_page_alloc = {
+ .attr = FAULT_ATTR_INITIALIZER,
+};
+
+static int __init setup_fail_page_alloc(char *str)
+{
+ return setup_fault_attr(&fail_page_alloc.attr, str);
+}
+__setup("fail_page_alloc=", setup_fail_page_alloc);
+
+static int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
+{
+ if (gfp_mask & __GFP_NOFAIL)
+ return 0;
+ if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
+ return 0;
+ if (fail_page_alloc.ignore_gfp_wait && (gfp_mask & __GFP_WAIT))
+ return 0;
+
+ return should_fail(&fail_page_alloc.attr, 1 << order);
+}
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+static int __init fail_page_alloc_debugfs(void)
+{
+ mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+ struct dentry *dir;
+ int err;
+
+ err = init_fault_attr_dentries(&fail_page_alloc.attr,
+ "fail_page_alloc");
+ if (err)
+ return err;
+ dir = fail_page_alloc.attr.dentries.dir;
+
+ fail_page_alloc.ignore_gfp_wait_file =
+ debugfs_create_bool("ignore-gfp-wait", mode, dir,
+ &fail_page_alloc.ignore_gfp_wait);
+
+ fail_page_alloc.ignore_gfp_highmem_file =
+ debugfs_create_bool("ignore-gfp-highmem", mode, dir,
+ &fail_page_alloc.ignore_gfp_highmem);
+
+ if (!fail_page_alloc.ignore_gfp_wait_file ||
+ !fail_page_alloc.ignore_gfp_highmem_file) {
+ err = -ENOMEM;
+ debugfs_remove(fail_page_alloc.ignore_gfp_wait_file);
+ debugfs_remove(fail_page_alloc.ignore_gfp_highmem_file);
+ cleanup_fault_attr_dentries(&fail_page_alloc.attr);
+ }
+
+ return err;
+}
+
+late_initcall(fail_page_alloc_debugfs);
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
+
+#else /* CONFIG_FAIL_PAGE_ALLOC */
+
+static inline int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
+{
+ return 0;
+}
+
+#endif /* CONFIG_FAIL_PAGE_ALLOC */
+
/*
* Return 1 if free pages are above 'mark'. This takes into account the order
* of the allocation.
@@ -1136,6 +1220,9 @@
might_sleep_if(wait);
+ if (should_fail_alloc_page(gfp_mask, order))
+ return NULL;
+
restart:
z = zonelist->zones; /* the list of zones suitable for gfp_mask */