From af3b854492f351d1ff3b4744a83bf5ff7eed4920 Mon Sep 17 00:00:00 2001 From: Benjamin Poirier Date: Fri, 28 Dec 2018 00:39:23 -0800 Subject: [PATCH] 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 Acked-by: Vlastimil Babka Cc: Arnd Bergmann Cc: Michal Hocko Cc: Pavel Tatashin Cc: Oscar Salvador Cc: Mike Rapoport Cc: Joonsoo Kim Cc: Alexander Duyck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/error-injection.h | 1 + mm/page_alloc.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/include/asm-generic/error-injection.h b/include/asm-generic/error-injection.h index 296c65442f00..95a159a4137f 100644 --- a/include/asm-generic/error-injection.h +++ b/include/asm-generic/error-injection.h @@ -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 { diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 75865e1325b5..cde5dac6229a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -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