On 2017/5/2 17:16, Michal Hocko wrote: > On Tue 02-05-17 16:52:00, Xishi Qiu wrote: >> On 2017/5/2 16:43, Michal Hocko wrote: >> >>> On Tue 02-05-17 15:59:23, Xishi Qiu wrote: >>>> Hi, I use "memtester -p 0x6c80000000000 10G" to test physical address 0x6c80000000000 >>>> Because this physical address is invalid, and valid_mmap_phys_addr_range() >>>> always return 1, so it causes crash. >>>> >>>> My question is that should the user assure the physical address is valid? >>> >>> We already seem to be checking range_is_allowed(). What is your >>> CONFIG_STRICT_DEVMEM setting? The code seems to be rather confusing but >>> my assumption is that you better know what you are doing when mapping >>> this file. >>> >> >> HI Michal, >> >> CONFIG_STRICT_DEVMEM=y, and range_is_allowed() will skip memory, but >> 0x6c80000000000 is not memory, it is just a invalid address, so it cause >> crash. > > OK, I only now looked at the value. It is beyond addressable limit > (for 47b address space). None of the checks seems to stop this because > range_is_allowed() resp. its devmem_is_allowed() will allow it as a > non RAM (!page_is_ram check). I am not really sure how to fix this or > whether even we should try to fix this particular problem. As I've said > /dev/mem is dangerous and you should better know what you are doing when > accessing it. > OK, I know, thank you! Thanks, Xishi Qiu -- 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>
