Messages in this thread Patch in this message | | | Subject | Re: WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f6f6e1a4), by kmemleak's scan_block() | From | Pekka Enberg <> | Date | Tue, 25 Aug 2009 11:45:14 +0300 |
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On Tue, 2009-08-25 at 10:32 +0200, Ingo Molnar wrote: > > In any case, I don't think it is very productive to run them both > > at the same time, simply because kmemcheck slows every memory > > access down so much and scanning memory doesn't exactly help that. > > It _could_ be useful to have them compiled into the same kernel, > > though, e.g. a distro "-debug" kernel. > > > > Maybe you can just add the "depends on !KMEMLEAK" to > > CONFIG_KMEMCHECK in tip/out-of-tree for now? > > i think it would be far more intelligent to annotate those accesses > by kmemleak as 'trust me, dont check'. Willing to test such a patch.
I guess something like this totally untested patch should do it. Vegard, Catalin?
Pekka
diff --git a/arch/x86/mm/kmemcheck/kmemcheck.c b/arch/x86/mm/kmemcheck/kmemcheck.c index 2c55ed0..528bf95 100644 --- a/arch/x86/mm/kmemcheck/kmemcheck.c +++ b/arch/x86/mm/kmemcheck/kmemcheck.c @@ -331,6 +331,20 @@ static void kmemcheck_read_strict(struct pt_regs *regs, kmemcheck_shadow_set(shadow, size); } +bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size) +{ + enum kmemcheck_shadow status; + void *shadow; + + shadow = kmemcheck_shadow_lookup(addr); + if (!shadow) + return true; + + status = kmemcheck_shadow_test(shadow, size); + + return status == KMEMCHECK_SHADOW_INITIALIZED; +} + /* Access may cross page boundary */ static void kmemcheck_read(struct pt_regs *regs, unsigned long addr, unsigned int size) diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h index 47b39b7..dc2fd54 100644 --- a/include/linux/kmemcheck.h +++ b/include/linux/kmemcheck.h @@ -34,6 +34,8 @@ void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n); int kmemcheck_show_addr(unsigned long address); int kmemcheck_hide_addr(unsigned long address); +bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size); + #else #define kmemcheck_enabled 0 @@ -99,6 +101,11 @@ static inline void kmemcheck_mark_initialized_pages(struct page *p, { } +static inline bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size) +{ + return true; +} + #endif /* CONFIG_KMEMCHECK */ /* diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 4872673..c14d6e4 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -97,6 +97,7 @@ #include <asm/processor.h> #include <asm/atomic.h> +#include <linux/kmemcheck.h> #include <linux/kmemleak.h> /* @@ -949,6 +950,8 @@ static void scan_object(struct kmemleak_object *object) if (!(object->flags & OBJECT_ALLOCATED)) /* already freed object */ goto out; + if (!kmemcheck_is_obj_initialized(object->pointer, object->size)) + goto out; if (hlist_empty(&object->area_list)) scan_block((void *)object->pointer, (void *)(object->pointer + object->size), object, 0);
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