Zdenek Kabelac wrote: > Hello > > > I'm having weird problem and being a bit puzzled about where to look > for this bug. > > I'm using T61 - C2D 2GB > > So I'll describe symptoms: > > When I run inside my 0.5G smp qemu-kvm guest with Debian these two > loops in parallel: > > 'while : ; do dmsetup status ; done' > > and > > 'while : ; do cat /dev/zero >/dev/mapper/any_free_to_use_lvm_partition ; done' > > after a while dmsetup start to loop in this place: > > [ 356.257323] [<ffffffff8117c017>] ? copy_user_generic_string+0x17/0x40 > > > I'm using preemptible kernel and the code will stay in the > copy_user_generic_string call forever eating 100%cpu - without > preemption the kernel gets dead. > > With preemption when I run at this moment second dmsetup status in > paralllel the busy-looped dmsetup gets finished and while loop starts > to continue agains until next dmsetup busy-loop. > > I've noticed that if I change inside drivers/md/dm-ioctl.c > copy_params the parameter tmp.data_size in the copy_from_user call to > just page size (4kB) - or when I replace vmalloc to kmalloc - the busy > loop will not happen. > > So it seems to be related to page jump somehow > > Anyway might have any idea - what is going on here ? >
Most likely movs emulation is broken for long counts. Please post a disassembly of copy_user_generic_string to make sure we're looking at the same code. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
