FYI, we noticed the below changes on

https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/mm
commit edfe63ec97ed8d4496225f7ba54c9ce4207c5431 ("x86/mtrr: Fix Xorg crashes in Qemu sessions")


[   10.429879] hgafb: HGA card not detected.
[   10.430521] hgafb: probe of hgafb.0 failed with error -22
[   10.434199] ------------[ cut here ]------------
[   10.434889] kernel BUG at arch/x86/mm/physaddr.c:79!
[   10.435784] invalid opcode: 0000 [#1] DEBUG_PAGEALLOC 
[   10.436627] CPU: 0 PID: 117 Comm: v86d Not tainted 4.6.0-rc1-00015-gedfe63e #1
[   10.437696] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[   10.438929] task: cf91d900 ti: cf8fa000 task.ti: cf8fa000
[   10.439664] EIP: 0060:[<c1033290>] EFLAGS: 00010206 CPU: 0
[   10.440409] EIP is at __phys_addr+0x80/0x90
[   10.441022] EAX: 13fe0000 EBX: 13fe0000 ECX: 00000000 EDX: 13fe0000
[   10.441975] ESI: 00000000 EDI: 00000000 EBP: cf8fbe4c ESP: cf8fbe48
[   10.442804]  DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
[   10.443534] CR0: 80050033 CR2: 08063e48 CR3: 0f9f8f20 CR4: 000006b0
[   10.444362] Stack:
[   10.444772]  cf9e4dfc cf8fbe60 c1031eef 00000001 00001000 00000000 cf8fbea8 c15952d1
[   10.446322]  cf9e4dfc d3a23518 c10fce12 024080c0 024080c0 d2b05c80 00000000 00000000
[   10.447870]  d15da220 cf9e4dd8 00001000 00001000 00000000 cf9ed790 b7752000 cf9ed788
[   10.449424] Call Trace:
[   10.449877]  [<c1031eef>] phys_mem_access_prot_allowed+0xaf/0xf0
[   10.450670]  [<c15952d1>] mmap_mem+0xa1/0x170
[   10.451308]  [<c10fce12>] ? mmap_region+0x242/0x510
[   10.451993]  [<c10fce9a>] mmap_region+0x2ca/0x510
[   10.452657]  [<c10fd30d>] do_mmap+0x22d/0x300
[   10.453313]  [<c10e7d74>] vm_mmap_pgoff+0x54/0x80
[   10.453985]  [<c10fb211>] SyS_mmap_pgoff+0xa1/0x100
[   10.454665]  [<c10013c3>] do_int80_syscall_32+0x63/0x150
[   10.455396]  [<c1b2684e>] entry_INT80_32+0x36/0x36
[   10.456072] Code: c2 8d 91 00 00 80 00 39 d0 72 ba 8b 0d ec e4 ed c1 8d 91 00 e0 dc ff 81 e2 00 00 e0 ff 81 ea 00 20 00 00 39 d0 73 9e 0f 0b 66 90 <0f> 0b 8d b4 26 00 00 00 00 8d bc 27 00 00 00 00 3d ff ff ff bf
[   10.461981] EIP: [<c1033290>] __phys_addr+0x80/0x90 SS:ESP 0068:cf8fbe48
[   10.462996] ---[ end trace ae02c62f21ceed39 ]---
[   10.463675] Kernel panic - not syncing: Fatal exception


FYI, raw QEMU command line is:

	qemu-system-i386 -enable-kvm -kernel /pkg/linux/i386-randconfig-b0-03311500/gcc-5/edfe63ec97ed8d4496225f7ba54c9ce4207c5431/vmlinuz-4.6.0-rc1-00015-gedfe63e -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-yocto-i386-31/bisect_boot-1-yocto-minimal-i386.cgz-i386-randconfig-b0-03311500-edfe63ec97ed8d4496225f7ba54c9ce4207c5431-20160331-66540-qp1ggl-0.yaml ARCH=i386 kconfig=i386-randconfig-b0-03311500 branch=linux-devel/devel-spot-201603311424 commit=edfe63ec97ed8d4496225f7ba54c9ce4207c5431 BOOT_IMAGE=/pkg/linux/i386-randconfig-b0-03311500/gcc-5/edfe63ec97ed8d4496225f7ba54c9ce4207c5431/vmlinuz-4.6.0-rc1-00015-gedfe63e max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-yocto-i386/yocto-minimal-i386.cgz/i386-randconfig-b0-03311500/gcc-5/edfe63ec97ed8d4496225f7ba54c9ce4207c5431/0 LKP_SERVER=inn earlyprintk=ttyS0,115200 systemd.log_level=err debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal rw ip=::::vm-kbuild-yocto-i386-31::dhcp drbd.minor_count=8'  -initrd /fs/sdh1/initrd-vm-kbuild-yocto-i386-31 -m 320 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -drive file=/fs/sdh1/disk0-vm-kbuild-yocto-i386-31,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-yocto-i386-31 -serial file:/dev/shm/kboot/serial-vm-kbuild-yocto-i386-31 -daemonize -display none -monitor null 




Thanks,
Kernel Test Robot