bisecting fixing commit since f4d51dffc6c01a9e94650d95ce0104964f8ae822
building syzkaller on abf9ba4fc75d9b29af15625d44dcfc1360fad3b7
testing commit f4d51dffc6c01a9e94650d95ce0104964f8ae822 with gcc (GCC) 8.1.0
kernel signature: bf20e0e01bd374904d0ff5d1e16cc0854f186c8d6fb8c54293168c2198b4928b
all runs: crashed: BUG: unable to handle kernel paging request in cfb_imageblit
testing current HEAD 583090b1b8232e6eae243a9009699666153a13a9
testing commit 583090b1b8232e6eae243a9009699666153a13a9 with gcc (GCC) 8.1.0
kernel signature: f30d444f7bed2ec5e2dd4b1b0029a570f4f4e4c330a467d5560b43be818e4609
all runs: crashed: BUG: unable to handle kernel paging request in cfb_imageblit
revisions tested: 2, total time: 16m31.034042689s (build: 10m5.293500452s, test: 6m1.905379679s)
the crash still happens on HEAD
commit msg: Merge tag 'block5.9-2020-10-08' of git://git.kernel.dk/linux-block
crash: BUG: unable to handle kernel paging request in cfb_imageblit
BUG: unable to handle page fault for address: ffff888001000000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD 6a01067 P4D 6a01067 PUD 6a02067 PMD 80000000010001e1 
Oops: 0003 [#1] PREEMPT SMP
CPU: 1 PID: 8338 Comm: syz-executor.0 Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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+0x188/0x4c0 drivers/video/fbdev/core/cfbimgblt.c:302
Code: c9 41 d3 fa 89 d1 41 83 e2 01 44 8b 54 24 18 44 0f 45 54 24 14 45 89 d5 41 d3 e5 44 09 e8 41 39 d6 4d 89 c5 77 1d 49 83 c5 04 <41> 89 00 b9 20 00 00 00 b8 00 00 00 00 29 d1 41 d3 ea 41 39 d6 41
RSP: 0018:ffffc90002c7fb70 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff888001000000 RCX: 000000000000001c
RDX: 000000000000001c RSI: 000000000000000f RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff888001000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffff888219ea3a00 R12: ffff888001000000
R13: ffff888001000004 R14: 000000000000001c R15: ffff888219ea3a00
FS:  00007f6424291700(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888001000000 CR3: 000000010f1cb000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:139 [inline]
 bit_putcs+0x27f/0x500 drivers/video/fbdev/core/bitblit.c:188
 fbcon_putcs+0xe4/0x100 drivers/video/fbdev/core/fbcon.c:1308
 con_flush drivers/tty/vt/vt.c:2575 [inline]
 vc_con_write_normal drivers/tty/vt/vt.c:2803 [inline]
 do_con_write+0x2db/0x9b0 drivers/tty/vt/vt.c:2910
 con_write+0xa/0x40 drivers/tty/vt/vt.c:3250
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x1a9/0x4e0 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x15f/0x320 drivers/tty/tty_io.c:1046
 vfs_write+0xc7/0x230 fs/read_write.c:584
 ksys_write+0x5a/0xd0 fs/read_write.c:639
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d5b9
Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f6424290c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000038900 RCX: 000000000045d5b9
RDX: 0000000000001006 RSI: 0000000020001440 RDI: 0000000000000007
RBP: 000000000118d020 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cfec
R13: 00007fffa5bb5c6f R14: 00007f64242919c0 R15: 000000000118cfec
Modules linked in:
CR2: ffff888001000000
---[ end trace 1ef82f54c7d71ce2 ]---
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+0x188/0x4c0 drivers/video/fbdev/core/cfbimgblt.c:302
Code: c9 41 d3 fa 89 d1 41 83 e2 01 44 8b 54 24 18 44 0f 45 54 24 14 45 89 d5 41 d3 e5 44 09 e8 41 39 d6 4d 89 c5 77 1d 49 83 c5 04 <41> 89 00 b9 20 00 00 00 b8 00 00 00 00 29 d1 41 d3 ea 41 39 d6 41
RSP: 0018:ffffc90002c7fb70 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff888001000000 RCX: 000000000000001c
RDX: 000000000000001c RSI: 000000000000000f RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff888001000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffff888219ea3a00 R12: ffff888001000000
R13: ffff888001000004 R14: 000000000000001c R15: ffff888219ea3a00
FS:  00007f6424291700(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888001000000 CR3: 000000010f1cb000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400