On 10/02/2013 11:31 AM, Frantisek Hrbata wrote: > On Wed, Oct 02, 2013 at 10:46:35AM -0700, H. Peter Anvin wrote: >> On 10/02/2013 09:05 AM, Frantisek Hrbata wrote: >>> + >>> +int valid_phys_addr_range(phys_addr_t addr, size_t count) >>> +{ >>> + return addr + count <= __pa(high_memory); >>> +} >>> + >>> +int valid_mmap_phys_addr_range(unsigned long pfn, size_t count) >>> +{ >>> + resource_size_t addr = (pfn << PAGE_SHIFT) + count; >>> + return phys_addr_valid(addr); >>> +} >>> >> >> The latter has overflow problems. > > Could you please specify what overflow problems do you mean? Consider if pfn + count overflows and wraps around, or if (pfn << PAGE_SHIFT) pushes bits out to the left. >> The former I realize matches the current /dev/mem, but it is still just >> plain wrong in multiple ways. > > I guess that you are talking about /dev/mem implementation generelly, because > this patch is exactly the same as the first one. All I'm trying to do here is to > fix this simple problem, which was reported by a customer, using IMHO the least > invasive way. Anyway is there any description what is wrong with /dev/mem > implementation? Maybe I can try to take a look. > The bottom line is that read/write to /dev/mem should be able to access the same memory that we can mmap(). Having two different tests is ridiculous. -hpa -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>