On 11/24/19 5:43 PM, Jackie Liu wrote: > > >> 2019年11月25日 01:52，Pavel Begunkov <asml.silence@xxxxxxxxx> 写道： >> >> On 24/11/2019 20:10, Jens Axboe wrote: >>> On 11/24/19 1:58 AM, Pavel Begunkov wrote: >>>> Read/write requests to devices without implemented read/write_iter >>>> using fixed buffers causes general protection fault, which totally >>>> hangs a machine. >>>> >>>> io_import_fixed() initialises iov_iter with bvec, but loop_rw_iter() >>>> accesses it as iovec, so dereferencing random address. >>>> >>>> kmap() page by page in this case >>> >>> This looks good to me, much cleaner/simpler. I've added a few pipe fixed >>> buffer tests to liburing as well. Didn't crash for me, but obvious >>> garbage coming out. I've flagged this for stable as well. >>> >> The problem I have is that __user pointer is meant to be checked >> for not being a kernel address. I suspect, it could fail in some >> device, which double checks the pointer after vfs (e.g. using access_ok()). >> Am I wrong? Not a fault at least... >> >> #define access_ok(...) __range_not_ok(addr, user_addr_max()); >> >> BTW, is there anybody testing it for non x86-64 arch? >> > > I have some aarch64 platform, What test do you want me to do? A basic one to try would be: axboe@x1:/home/axboe/git/liburing $ test/stdout This is a pipe test This is a fixed pipe test But in general I'd just run make runtests in the liburing directory and go through all of them. -- Jens Axboe
