On Thu, Nov 14, 2013 at 07:31:36PM -0500, Santosh Shilimkar wrote: > On Thursday 14 November 2013 07:22 PM, Christoffer Dall wrote: > > On Thu, Nov 14, 2013 at 02:37:43PM -0500, Santosh Shilimkar wrote: > >> Slab allocator can allocate memory beyond the lowmem watermark > >> which can lead to false failure of virt_addr_valid(). > >> > >> So drop the check. The issue was seen with percpu_alloc() > >> in KVM code which was allocating memory beyond lowmem watermark. > >> > >> Am not completly sure whether this is the right fix and if it could > >> impact any other user of virt_addr_valid(). Without this fix as > >> pointed out the KVM init was failing in my testing. > >> > >> Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > >> Cc: Marc Zyngier <marc.zyngier@xxxxxxx> > >> Cc: Russell King <linux@xxxxxxxxxxxxxxxx> > >> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > >> Cc: Will Deacon <will.deacon@xxxxxxx> > >> > >> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx> > >> --- > >> arch/arm/include/asm/memory.h | 3 +-- > >> 1 file changed, 1 insertion(+), 2 deletions(-) > >> > >> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h > >> index 4dd2145..412da47 100644 > >> --- a/arch/arm/include/asm/memory.h > >> +++ b/arch/arm/include/asm/memory.h > >> @@ -343,8 +343,7 @@ static inline __deprecated void *bus_to_virt(unsigned long x) > >> #define ARCH_PFN_OFFSET PHYS_PFN_OFFSET > >> > >> #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT) > >> -#define virt_addr_valid(kaddr) ((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory) > >> - > >> +#define virt_addr_valid(kaddr) ((unsigned long)(kaddr) >= PAGE_OFFSET) > >> #endif > >> > >> #include <asm-generic/memory_model.h> > >> -- > >> 1.7.9.5 > >> > > > > This looks wrong to me. Check Documentation/arm/memory.txt, this would > > return true for the VMALLOC region, which would cause virt_to_phys to > > give you something invalid, which would be bad. > > > I also thought it might not be right fix and hence added a disclaimer > in the commit message ;-) > Yes I know, I'm not holding it against you ;) Not sure what the nicest fix is though. I think we can get away with the single page restriction per call for Hyp mappings for now. IIRC the Hyp code is still limited to be within a single page. Let's see what Marc has to say. -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
