bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67
building syzkaller on fa79ed2ae1c546ca48519cfcd80d43b51b502750
testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0
kernel signature: a307ca84de4be5c9b4b447a498ff87339f6a13bd9f597609d99fe4c95fdab267
all runs: crashed: BUG: unable to handle kernel paging request in cfb_imageblit
testing current HEAD 6b6446efedb27c2766745a04f9b5d4449f51391d
testing commit 6b6446efedb27c2766745a04f9b5d4449f51391d with gcc (GCC) 8.1.0
kernel signature: fa3b35857a44d5b2598b53a514c159879aab71ace0df17eb00ef0da4058ea48f
all runs: crashed: BUG: unable to handle kernel paging request in cfb_imageblit
revisions tested: 2, total time: 23m13.114297633s (build: 16m53.414190053s, test: 5m41.627368193s)
the crash still happens on HEAD
commit msg: Linux 4.14.204
crash: BUG: unable to handle kernel paging request in cfb_imageblit
wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
BUG: unable to handle kernel paging request at ffff888001000000
IP: __writel arch/x86/include/asm/io.h:71 [inline]
IP: slow_imageblit drivers/video/fbdev/core/cfbimgblt.c:178 [inline]
IP: cfb_imageblit+0x741/0xec0 drivers/video/fbdev/core/cfbimgblt.c:302
PGD a547067 P4D a547067 PUD a548067 PMD 80000000010001e1 
Oops: 0003 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 8831 Comm: syz-executor.0 Not tainted 4.14.204-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809c73c600 task.stack: ffff888085338000
RIP: 0010:__writel arch/x86/include/asm/io.h:71 [inline]
RIP: 0010:slow_imageblit drivers/video/fbdev/core/cfbimgblt.c:178 [inline]
RIP: 0010:cfb_imageblit+0x741/0xec0 drivers/video/fbdev/core/cfbimgblt.c:302
RSP: 0018:ffff88808533f578 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 000000000000001c RCX: 000000000000001c
RDX: ffff888001000000 RSI: 0000000000000007 RDI: ffff888001000004
RBP: ffff88808533f630 R08: dffffc0000000000 R09: 0000000000000004
R10: 0000000000000000 R11: 000000000000001c R12: 0000000000000000
R13: ffff8880b1b39930 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f855e364700(0000) GS:ffff8880ba900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888001000000 CR3: 000000009d533000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vga_imageblit_expand drivers/video/fbdev/vga16fb.c:1208 [inline]
 vga16fb_imageblit+0x620/0x2380 drivers/video/fbdev/vga16fb.c:1261
 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:139 [inline]
 bit_putcs+0x870/0xc80 drivers/video/fbdev/core/bitblit.c:188
 fbcon_putcs+0x302/0x5f0 drivers/video/fbdev/core/fbcon.c:1247
 con_flush drivers/tty/vt/vt.c:2206 [inline]
 do_con_write.part.14+0x692/0x19c0 drivers/tty/vt/vt.c:2410
 do_con_write drivers/tty/vt/vt.c:2225 [inline]
 con_write+0x1f/0x80 drivers/tty/vt/vt.c:2805
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x498/0x1030 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:959 [inline]
 tty_write+0x342/0x770 drivers/tty/tty_io.c:1043
 __vfs_write+0xdb/0x840 fs/read_write.c:480
 vfs_write+0x150/0x4f0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0x100/0x250 fs/read_write.c:582
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45de29
RSP: 002b:00007f855e363c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000003a600 RCX: 000000000045de29
RDX: 0000000000001006 RSI: 0000000020001440 RDI: 0000000000000008
RBP: 000000000118c008 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4
R13: 00007fff7e6de35f R14: 00007f855e3649c0 R15: 000000000118bfd4
Code: c0 0f 85 91 03 00 00 41 0f b6 45 00 44 89 e1 d3 f8 89 d9 a8 01 44 89 d0 0f 45 c6 89 c7 d3 e7 41 09 ff 41 39 db 77 1f 48 8d 7a 04 <44> 89 3a 41 39 db 0f 84 51 02 00 00 b9 20 00 00 00 48 89 fa 29 
RIP: __writel arch/x86/include/asm/io.h:71 [inline] RSP: ffff88808533f578
RIP: slow_imageblit drivers/video/fbdev/core/cfbimgblt.c:178 [inline] RSP: ffff88808533f578
RIP: cfb_imageblit+0x741/0xec0 drivers/video/fbdev/core/cfbimgblt.c:302 RSP: ffff88808533f578
CR2: ffff888001000000
---[ end trace 85faba043a0ce330 ]---