On Sun, Nov 12, 2017 at 6:08 PM, kernel test robot <[email protected]> wrote: > > FYI, we noticed the following commit (built with gcc-6): > > commit: e04a713254ef50629d1ae9558ddd4c118b7cb807 ("x86/asm/64: Use a percpu > trampoline stack for IDT entries") > https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git > x86/entry_stack.wip > > in testcase: boot > > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -m 512M > > caused below changes (please refer to attached dmesg/kmsg for entire > log/backtrace): > > > +------------------------------------------+------------+------------+ > | | c82ad40da1 | e04a713254 | > +------------------------------------------+------------+------------+ > | boot_successes | 39 | 0 | > | boot_failures | 0 | 8 | > | double_fault:#[##] | 0 | 8 | > | RIP:__do_page_fault | 0 | 8 | > | Kernel_panic-not_syncing:Fatal_exception | 0 | 8 | > +------------------------------------------+------------+------------+ > > > > [ 187.211863] Freeing unused kernel memory: 1360K > [ 187.212799] Write protecting the kernel read-only data: 24576k > [ 187.226217] Freeing unused kernel memory: 1464K > [ 187.309521] Freeing unused kernel memory: 1556K > [ 187.310408] rodata_test: all tests were successful > [ 187.312781] double fault: 0000 [#1] PREEMPT KASAN > [ 187.313638] CPU: 0 PID: 1 Comm: init Not tainted 4.14.0-rc7-00070-ge04a713 > #1 > [ 187.318110] task: ffff88001a73d500 task.stack: ffff88001a740000 > [ 187.319112] RIP: 0010:__do_page_fault+0x66/0x53d > [ 187.319874] RSP: 0000:ffffffffff575fe8 EFLAGS: 00010086 > [ 187.320714] RAX: fffffbffffeaec05 RBX: ffffffffff5760f8 RCX: > ffffffff810c70b9 > [ 187.321961] RDX: fffffbffffeaec3d RSI: 0000000000000003 RDI: > ffff88001a73d720 > [ 187.323105] RBP: 0000000000000003 R08: dffffc0000000000 R09: > 0000000000000001 > [ 187.324261] R10: ffffffffff576e10 R11: 0000000000000000 R12: > fffffbffffeaec3d > [ 187.325481] R13: 0000000000000003 R14: fffffbffffeaec3d R15: > ffff88001a73d500 > [ 187.326656] FS: 0000000000000000(0000) GS:ffffffff82841000(0000) > knlGS:0000000000000000 > [ 187.327980] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 187.328993] CR2: ffffffffff575fd8 CR3: 000000001a41b000 CR4: > 00000000000406b0 > [ 187.330157] Call Trace: > [ 187.330582] Code: 41 48 c7 44 24 48 c1 41 5e 82 48 c7 44 24 50 00 67 03 81 > 48 c1 e8 03 48 89 44 24 18 48 b8 00 00 00 00 00 fc ff df 48 03 44 24 18 <c7> > 00 f1 f1 f1 f1 c7 40 04 04 f4 f4 f4 65 48 8b 04 25 28 00 00 > [ 187.346857] RIP: __do_page_fault+0x66/0x53d RSP: ffffffffff575fe8 > [ 187.347874] ---[ end trace 3b2af22d0dac3392 ]--- > [ 187.348663] Kernel panic - not syncing: Fatal exception > [ 187.349560] Kernel Offset: disabled
Wow, this email found at least three bugs :) Two of them caused the backtrace to be mostly worthless, and the third caused the crash in the first place. --Andy
