Commit 54114994 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
Browse files

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: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 203a2935

Documentation/fault-injection/fault-injection.txt

+5 −0
Original line number Diff line number Diff line
@@ -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),

mm/page_alloc.c

+11 −1
Original line number Diff line number Diff line
@@ -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);

	}

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