On Thu, Jan 11, 2018 at 06:03:47PM +0100, Peter Zijlstra wrote: > > On Thu, 11 Jan 2018, Vince Weaver wrote: > > [ 823.919729] BUG: unable to handle kernel paging request at > > ffff88011a7a1000 > > [ 823.926928] IP: 0x7fbda0042b3c > > > > I'm dumping vmlinux and can't find address 0x7fbda0042b3c at all. > > That's a user address..
> > [ 823.930123] PGD 22ea067 P4D 22ea067 PUD 22ed067 PMD 11a520063 PTE > > 800000011a7a1063 > > [ 823.938012] Oops: 0002 [#1] SMP PTI > > [ 823.968898] CPU: 1 PID: 17688 Comm: perf_fuzzer Not tainted 4.15.0-rc7+ > > #211 > > [ 823.976152] Hardware name: AOpen DE7000/nMCP7ALPx-DE R1.06 > > Oct.19.2012, BIOS 080015 10/19/2012 > > [ 823.985259] RIP: 0033:0x7fbda0042b3c > > [ 823.989002] RSP: 002b:00007ffed7fa46c8 EFLAGS: 00010246 > > [ 823.994434] RAX: 000000000000462d RBX: 000000000000000c RCX: > > 00007fbda0042b3c > > [ 824.001786] RDX: 0000000000000000 RSI: 00007ffed7fa46dc RDI: > > 000000000000462d > > [ 824.009135] RBP: 00007ffed7fa46e0 R08: 00007fbda032e0e4 R09: > > 0000000000000000 > > [ 824.016483] R10: 0000000000000000 R11: 0000000000000246 R12: > > 0000000000401950 > > [ 824.023832] R13: 00007ffed7fa6ae0 R14: 0000000000000000 R15: > > 0000000000000000 > > [ 824.031198] FS: 00007fbda0540700(0000) GS:ffff88011fc80000(0000) > > knlGS:0000000000000000 > > [ 824.039530] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 824.045477] CR2: ffff88011a7a1000 CR3: 000000011a998000 CR4: > > 00000000000407e0 > > [ 824.052827] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > 0000000000000000 > > [ 824.060176] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: > > 0000000000000600 > > [ 824.072767] CR2: ffff88011a7a1000 > > [ 824.076248] ---[ end trace 31d5336f74638197 ]-- So its faulting while looking up the userspace page tables, so something buggered. The CR3 has bit 12 clear so its a kernel CR3, which is also somewhat puzzling. Oooh, right, its the CR3 from when we report the OOPS, which is less than useful. I can't get further than that the page-tables are screwed..
