Commit 933e312e authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
Browse files

[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: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8a8b6502

lib/Kconfig.debug

+7 −0
Original line number Diff line number Diff line
@@ -424,6 +424,13 @@ config FAILSLAB 
	help

	  This option provides fault-injection capabilitiy for kmalloc.



config FAIL_PAGE_ALLOC

	bool "Fault-injection capabilitiy for alloc_pages()"

	depends on DEBUG_KERNEL

	select FAULT_INJECTION

	help

	  This option provides fault-injection capabilitiy for alloc_pages().



config FAULT_INJECTION_DEBUG_FS

	bool "Debugfs entries for fault-injection capabilities"

	depends on FAULT_INJECTION && SYSFS

mm/page_alloc.c

+87 −0
Original line number Diff line number Diff line
@@ -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 @@ static struct page *buffered_rmqueue(struct zonelist *zonelist, 
#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 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order, 


	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 */