On Fri, Apr 25, 2008 at 12:36:33PM -0700, Christoph Lameter wrote: > On Fri, 25 Apr 2008, Andi Kleen wrote: > > > > And we should really add a lot more sanity checking there. > > > > A debug mode for virt_to_page(),__pa,__va et.al. would probably make sense > > and would have caught it. > > > > I used to have that partly in the x86-64 port with VIRTUAL_BUG_ON. > > Good idea! Do you have a patch? Yes. Appended. But it just enables the old NUMA VIRTUAL_BUG_ON()s, more work could be done e.g. by instrumenting pa/va and the non NUMA and i386 case too. -Andi --- Add CONFIG option to enable VIRTUAL_BUG_ON() VIRTUAL_BUG_ON was used in the early days of x86-64 NUMA to debug the virtual address to struct page code. Later it was noped, but the call kept intact. Add a CONFIG option to enable it as a BUG_ON again. This would have likely caught the recent text_poke bug. Signed-off-by: Andi Kleen <andi@xxxxxxxxxxxxxx> Index: linux/arch/x86/Kconfig.debug =================================================================== --- linux.orig/arch/x86/Kconfig.debug +++ linux/arch/x86/Kconfig.debug @@ -245,4 +245,11 @@ config CPA_DEBUG help Do change_page_attr() self-tests every 30 seconds. +config DEBUG_VIRTUAL + bool "Virtual memory translation debugging" + depends on DEBUG_KERNEL && NUMA && X86_64 + help + Enable some costly sanity checks in the NUMA virtual to page + code. This can catch mistakes with virt_to_page() and friends. + endmenu Index: linux/include/asm-x86/mmzone_64.h =================================================================== --- linux.orig/include/asm-x86/mmzone_64.h +++ linux/include/asm-x86/mmzone_64.h @@ -7,7 +7,11 @@ #ifdef CONFIG_NUMA +#ifdef CONFIG_DEBUG_VIRTUAL +#define VIRTUAL_BUG_ON(x) BUG_ON(x) +#else #define VIRTUAL_BUG_ON(x) +#endif #include <asm/smp.h> -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
