Commit af3b8544 authored Dec 28, 2018 by Benjamin Poirier Committed by Linus Torvalds Dec 28, 2018

mm/page_alloc.c: allow error injection

Model call chain after should_failslab().  Likewise, we can now use a
kprobe to override the return value of should_fail_alloc_page() and inject
allocation failures into alloc_page*().

This will allow injecting allocation failures using the BCC tools even
without building kernel with CONFIG_FAIL_PAGE_ALLOC and booting it with a
fail_page_alloc= parameter, which incurs some overhead even when failures
are not being injected.  On the other hand, this patch adds an
unconditional call to should_fail_alloc_page() from page allocation
hotpath.  That overhead should be rather negligible with
CONFIG_FAIL_PAGE_ALLOC=n when there's no kprobe attached, though.

[vbabka@suse.cz: changelog addition]
Link: http://lkml.kernel.org/r/20181214074330.18917-1-bpoirier@suse.com


Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ab41ee68

include/asm-generic/error-injection.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -8,6 +8,7 @@ enum {
		EI_ETYPE_NULL, /* Return NULL if failure */
		EI_ETYPE_ERRNO, /* Return -ERRNO if failure */
		EI_ETYPE_ERRNO_NULL, /* Return -ERRNO or NULL if failure */
		EI_ETYPE_TRUE, /* Return true if failure */
		};

		struct error_injection_entry {

mm/page_alloc.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -3131,7 +3131,7 @@ static int __init setup_fail_page_alloc(char *str)
		}
		__setup("fail_page_alloc=", setup_fail_page_alloc);

		static bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
		static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
		{
		if (order < fail_page_alloc.min_order)
		return false;
		@@ -3181,13 +3181,19 @@ late_initcall(fail_page_alloc_debugfs);

		#else /* CONFIG_FAIL_PAGE_ALLOC */

		static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
		static inline bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
		{
		return false;
		}

		#endif /* CONFIG_FAIL_PAGE_ALLOC */

		static noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
		{
		return __should_fail_alloc_page(gfp_mask, order);
		}
		ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);

		/*
		* Return true if free base pages are above 'mark'. For high-order checks it
		* will return true of the order-0 watermark is reached and there is at least