On Sat, Mar 14, 2015 at 11:16:20PM +0100, Stefan Seyfried wrote:
[242060.605396] CPU: 1 PID: 2132 Comm: qemu-system-x86 Tainted: G W 4.0.0-rc3-2.gd5c547f-desktop #1 [242060.605396] Hardware name: LENOVO 74665EG/74665EG, BIOS 6DET71WW (3.21 ) 12/13/2011 [242060.605396] task: ffff880103f46150 ti: ffff8801013d4000 task.ti: ffff8801013d4000 [242060.605396] RIP: 0010:[<ffffffff81005b44>] [<ffffffff81005b44>] show_stack_log_lvl+0x124/0x190 [242060.605396] RSP: 0018:ffff88023bc84e88 EFLAGS: 00010046 [242060.605396] RAX: 00007fffa55eafc0 RBX: 00007fffa55eafb8 RCX: ffff88023bc7ffc0 [242060.605396] RDX: 0000000000000000 RSI: ffff88023bc84f58 RDI: 0000000000000000 [242060.605396] RBP: ffff88023bc83fc0 R08: ffffffff81a2fe15 R09: 0000000000000020 [242060.605396] R10: 0000000000000afb R11: ffff88023bc84bee R12: ffff88023bc84f58 [242060.605396] R13: 0000000000000000 R14: ffffffff81a2fe15 R15: 0000000000000000 [242060.605396] FS: 00007ffa33dbfa80(0000) GS:ffff88023bc80000(0000) knlGS:0000000000000000 [242060.605396] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [242060.605396] CR2: 00007fffa55eafb8 CR3: 0000000002d7e000 CR4: 00000000000427e0 [242060.605396] Stack: [242060.605396] 0000000002d7e000 0000000000000008 ffff88023bc84ee8 00007fffa55eafb8 [242060.605396] 0000000000000000 ffff88023bc84f58 00007fffa55eafb8 0000000000000040 [242060.605396] 00007ffa356b5d60 000000000000000f 00007ffa3556cf20 ffffffff81005c36 [242060.605396] Call Trace: [242060.605396] [<ffffffff81005c36>] show_regs+0x86/0x210 [242060.605396] [<ffffffff8104636f>] df_debug+0x1f/0x30 [242060.605396] [<ffffffff810041a4>] do_double_fault+0x84/0x100 [242060.605396] [<ffffffff81683088>] double_fault+0x28/0x30 [242060.605396] [<ffffffff816834ad>] page_fault+0xd/0x30 [242060.605396] Code: fe a2 81 31 c0 89 54 24 08 48 89 0c 24 48 8b 5b f8 e8 cc 06 67 00 48 8b 0c 24 8b 54 24 08 85 d2 74 05 f6 c2 03 74 48 48 8d 43 08 <48> 8b 33 48 c7 c7 0d fe a2 81 89 54 24 14 48 89 4c 24 08 48 89 [242060.605396] RIP [<ffffffff81005b44>] show_stack_log_lvl+0x124/0x190 [242060.605396] RSP <ffff88023bc84e88> [242060.605396] CR2: 00007fffa55eafb8
I encountered a similar problem recently. The thing is, x86 specification says that on a double fault, RIP and RSP registers are undefined, i.e. you not only can't expect them to contain values corresponding to the first or second fault but you can't even expect them to have any usable values at all. Unfortunately the kernel double fault handler doesn't take this into account and does try to display usual crash related information so that it itself does usually crash when trying to show stack content (that's the show_stack_log_lvl() crash). The result is a double fault (which itself would be very hard to debug) followed by a crash in its handler so that analysing the outcome is extremely difficult. Michal Kubeček -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org