fault-injection: add min-order parameter to fail_page_alloc

Limiting smaller allocation failures by fault injection helps to find real
possible bugs.  Because higher order allocations are likely to fail and
zero-order allocations are not likely to fail.

This patch adds min-order parameter to fail_page_alloc.  It specifies the
minimum page allocation order to be injected failures.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt
index b7ca560..36ece09 100644 (file)
--- a/Documentation/fault-injection/fault-injection.txt
+++ b/Documentation/fault-injection/fault-injection.txt
@@ -103,6 +103,11 @@ configuration of fault-injection capabilities.
        default is 'N', setting it to 'Y' will inject failures
        only into non-sleep allocations (GFP_ATOMIC allocations).
 
+- /debug/fail_page_alloc/min-order:
+
+       specifies the minimum page allocation order to be injected
+       failures.
+
 o Boot option
 
 In order to inject faults while debugfs is not available (early boot time),

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 297efcf..f9e4e64 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -900,11 +900,13 @@ static struct fail_page_alloc_attr {
 
        u32 ignore_gfp_highmem;
        u32 ignore_gfp_wait;
+       u32 min_order;
 
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 
        struct dentry *ignore_gfp_highmem_file;
        struct dentry *ignore_gfp_wait_file;
+       struct dentry *min_order_file;
 
 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
 
@@ -912,6 +914,7 @@ static struct fail_page_alloc_attr {
        .attr = FAULT_ATTR_INITIALIZER,
        .ignore_gfp_wait = 1,
        .ignore_gfp_highmem = 1,
+       .min_order = 1,
 };
 
 static int __init setup_fail_page_alloc(char *str)
@@ -922,6 +925,8 @@ __setup("fail_page_alloc=", setup_fail_page_alloc);
 
 static int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
 {
+       if (order < fail_page_alloc.min_order)
+               return 0;
        if (gfp_mask & __GFP_NOFAIL)
                return 0;
        if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
@@ -953,12 +958,17 @@ static int __init fail_page_alloc_debugfs(void)
        fail_page_alloc.ignore_gfp_highmem_file =
                debugfs_create_bool("ignore-gfp-highmem", mode, dir,
                                      &fail_page_alloc.ignore_gfp_highmem);
+       fail_page_alloc.min_order_file =
+               debugfs_create_u32("min-order", mode, dir,
+                                  &fail_page_alloc.min_order);
 
        if (!fail_page_alloc.ignore_gfp_wait_file ||
-                       !fail_page_alloc.ignore_gfp_highmem_file) {
+            !fail_page_alloc.ignore_gfp_highmem_file ||
+            !fail_page_alloc.min_order_file) {
                err = -ENOMEM;
                debugfs_remove(fail_page_alloc.ignore_gfp_wait_file);
                debugfs_remove(fail_page_alloc.ignore_gfp_highmem_file);
+               debugfs_remove(fail_page_alloc.min_order_file);
                cleanup_fault_attr_dentries(&fail_page_alloc.attr);
        }