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] dmsetup R running task 0 3385 2342 [ 356.257323] ffff81001c9fbc58 ffffffff812ee85e 0000000000000000 0000000000000001 [ 356.257323] 0000000000070617 0000000000000001 ffff81001be94000 ffff81001f864000 [ 356.257323] ffff81001be94360 000000018100cddc ffff81001be94000 ffffffff812f13b1 [ 356.257323] Call Trace: [ 356.257323] [<ffffffff812ee85e>] ? thread_return+0x99/0x51b [ 356.257323] [<ffffffff812f13b1>] ? trace_hardirqs_on_thunk+0x35/0x3a [ 356.257323] [<ffffffff81065749>] ? trace_hardirqs_on+0x139/0x1a0 [ 356.257323] [<ffffffff812f13b1>] ? trace_hardirqs_on_thunk+0x35/0x3a [ 356.257323] [<ffffffff8100cddc>] ? restore_args+0x0/0x30 [ 356.257323] [<ffffffff8117c017>] ? copy_user_generic_string+0x17/0x40 [ 356.257323] [<ffffffff8804c527>] ? :dm_mod:copy_params+0x87/0xb0 [ 356.257323] [<ffffffff81047d11>] ? __capable+0x11/0x30 [ 356.257323] [<ffffffff8804c6b9>] ? :dm_mod:ctl_ioctl+0x169/0x260 [ 356.257323] [<ffffffff8804c7dd>] ? :dm_mod:dm_compat_ctl_ioctl+0xd/0x20 [ 356.257323] [<ffffffff810f6c12>] ? compat_sys_ioctl+0x182/0x3d0 [ 356.257323] [<ffffffff810bbba0>] ? vfs_write+0x130/0x170 [ 356.257323] [<ffffffff812f13eb>] ? trace_hardirqs_off_thunk+0x35/0x37 [ 356.257323] [<ffffffff8102aec2>] ? sysenter_do_call+0x1b/0x70 [ 356.257323] [<ffffffff812f13b1>] ? trace_hardirqs_on_thunk+0x35/0x3a 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 ? Thanks Zdenek Cc me please I'm not a litst member. ------------------------------------------------------------------------- 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
