bisecting fixing commit since fdc072324f3c66190a20f57490b4842a391d8233 building syzkaller on 58ae5e18624eaaac79cab00e63d6f32c9bd64ee0 testing commit fdc072324f3c66190a20f57490b4842a391d8233 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 5dea0fd4b53db077d7093e85e42bdad72ee155b00ee7980da3dbdad1f95a3bcc all runs: crashed: BUG: unable to handle kernel paging request in cfb_imageblit testing current HEAD 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 21f06e2a8144851e3a208a56dc5d69f41acf92fbd78190ae9cdb457aabd32cb3 all runs: crashed: BUG: unable to handle kernel paging request in cfb_imageblit revisions tested: 2, total time: 31m5.735784536s (build: 23m41.855769889s, test: 6m39.512591389s) the crash still happens on HEAD commit msg: Linux 4.19.204 crash: BUG: unable to handle kernel paging request in cfb_imageblit IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready BUG: unable to handle kernel paging request at ffff888001000090 PGD ae01067 P4D ae01067 PUD ae02067 PMD 80000000010001e1 Oops: 0003 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7556 Comm: syz-executor.0 Not tainted 4.19.204-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+0x537/0xd90 drivers/video/fbdev/core/cfbimgblt.c:302 Code: 06 00 00 0f b6 06 44 89 c1 d3 f8 44 89 f9 a8 01 8b 45 b0 0f 45 45 b8 89 c7 d3 e7 41 09 fd 45 39 f9 4c 89 f7 77 1e 48 83 c7 04 <45> 89 2e b9 20 00 00 00 41 bd 00 00 00 00 44 29 f9 d3 e8 45 39 f9 RSP: 0018:ffff8881d3a27518 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888001000090 RCX: 000000000000001c RDX: 0000000000000000 RSI: ffff8881eecd5362 RDI: ffff888001000094 RBP: ffff8881d3a275c8 R08: 0000000000000000 R09: 000000000000001c R10: ffff888000ffff00 R11: 000000000000000d R12: 0000000000000000 R13: 0000000000000000 R14: ffff888001000090 R15: 000000000000001c FS: 00007f0eab439700(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888001000090 CR3: 00000001ed234001 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga_imageblit_expand drivers/video/fbdev/vga16fb.c:1207 [inline] vga16fb_imageblit+0x620/0x2380 drivers/video/fbdev/vga16fb.c:1260 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:139 [inline] bit_putcs+0x818/0xde0 drivers/video/fbdev/core/bitblit.c:188 fbcon_putcs+0x2fb/0x5a0 drivers/video/fbdev/core/fbcon.c:1269 con_flush drivers/tty/vt/vt.c:2560 [inline] do_con_write.part.20+0x73b/0x1aa0 drivers/tty/vt/vt.c:2765 do_con_write drivers/tty/vt/vt.c:2579 [inline] con_write+0x1f/0x80 drivers/tty/vt/vt.c:3146 process_output_block drivers/tty/n_tty.c:593 [inline] n_tty_write+0x4a4/0x1060 drivers/tty/n_tty.c:2331 do_tty_write drivers/tty/tty_io.c:960 [inline] tty_write+0x346/0x770 drivers/tty/tty_io.c:1044 __vfs_write+0xe3/0x890 fs/read_write.c:485 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464149 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0eab439198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464149 RDX: 0000000000001006 RSI: 0000000020000000 RDI: 0000000000000006 RBP: 0000000000524f20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055c040 R13: 00007f0eab4396bc R14: 00000000ffffffff R15: 0000000000000003 Modules linked in: CR2: ffff888001000090 ---[ end trace 49f29f7f42bd4018 ]--- 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+0x537/0xd90 drivers/video/fbdev/core/cfbimgblt.c:302 Code: 06 00 00 0f b6 06 44 89 c1 d3 f8 44 89 f9 a8 01 8b 45 b0 0f 45 45 b8 89 c7 d3 e7 41 09 fd 45 39 f9 4c 89 f7 77 1e 48 83 c7 04 <45> 89 2e b9 20 00 00 00 41 bd 00 00 00 00 44 29 f9 d3 e8 45 39 f9 RSP: 0018:ffff8881d3a27518 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888001000090 RCX: 000000000000001c RDX: 0000000000000000 RSI: ffff8881eecd5362 RDI: ffff888001000094 RBP: ffff8881d3a275c8 R08: 0000000000000000 R09: 000000000000001c R10: ffff888000ffff00 R11: 000000000000000d R12: 0000000000000000 R13: 0000000000000000 R14: ffff888001000090 R15: 000000000000001c FS: 00007f0eab439700(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888001000090 CR3: 00000001ed234001 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 00 00 add %al,(%rax) 2: 0f b6 06 movzbl (%rsi),%eax 5: 44 89 c1 mov %r8d,%ecx 8: d3 f8 sar %cl,%eax a: 44 89 f9 mov %r15d,%ecx d: a8 01 test $0x1,%al f: 8b 45 b0 mov -0x50(%rbp),%eax 12: 0f 45 45 b8 cmovne -0x48(%rbp),%eax 16: 89 c7 mov %eax,%edi 18: d3 e7 shl %cl,%edi 1a: 41 09 fd or %edi,%r13d 1d: 45 39 f9 cmp %r15d,%r9d 20: 4c 89 f7 mov %r14,%rdi 23: 77 1e ja 0x43 25: 48 83 c7 04 add $0x4,%rdi * 29: 45 89 2e mov %r13d,(%r14) <-- trapping instruction 2c: b9 20 00 00 00 mov $0x20,%ecx 31: 41 bd 00 00 00 00 mov $0x0,%r13d 37: 44 29 f9 sub %r15d,%ecx 3a: d3 e8 shr %cl,%eax 3c: 45 39 f9 cmp %r15d,%r9d