bisecting fixing commit since cb95712138ec5e480db5160b41172bbc6f6494cc
building syzkaller on cef5ae6814696260ff58c538a1b6044af90c5979
testing commit cb95712138ec5e480db5160b41172bbc6f6494cc with gcc (GCC) 8.1.0
kernel signature: 292fa100968031ef86b631f6b7bcc248fdf05f248f6765662fbb3dd9b8132f00
all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in bdev_read_page
testing current HEAD fa02fcd94b0c8dff6cc65714510cf25ad194b90d
testing commit fa02fcd94b0c8dff6cc65714510cf25ad194b90d with gcc (GCC) 8.1.0
kernel signature: c26d93c03954e4c788ee51eb56b3fd4b5f98e291ba174f94495574b5e98b27d4
all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in bdev_read_page
revisions tested: 2, total time: 15m39.101229285s (build: 9m34.799973594s, test: 5m28.271615887s)
the crash still happens on HEAD
commit msg: Merge tag 'media/v5.10-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
crash: BUG: unable to handle kernel NULL pointer dereference in bdev_read_page
BUG: kernel NULL pointer dereference, address: 0000000000000130
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 8298 Comm: systemd-udevd Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:bdev_read_page+0xa/0xa0 fs/block_dev.c:719
Code: 48 8b 38 48 81 ef d8 01 00 00 e8 b1 fe ff ff 31 c0 c3 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 41 55 41 54 55 53 48 83 ec 08 <48> 8b 87 30 01 00 00 4c 8b a8 e0 05 00 00 49 83 7d 18 00 74 75 48
RSP: 0018:ffffc90002a57ad0 EFLAGS: 00010282

RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000014
RDX: ffffea0004791380 RSI: a000479138000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 000000000000001d
R13: 0000000000000000 R14: a000479138000000 R15: ffffc90002a57bc0
FS:  00007fe8f483e8c0(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000130 CR3: 000000011d780000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 do_mpage_readpage+0x52a/0x870 fs/mpage.c:302
 mpage_readahead+0xf3/0x220 fs/mpage.c:391
 read_pages+0x8a/0x3f0 mm/readahead.c:130
 page_cache_ra_unbounded+0x142/0x270 mm/readahead.c:238
 page_cache_sync_readahead include/linux/pagemap.h:839 [inline]
 generic_file_buffered_read+0x626/0x850 mm/filemap.c:2235
 call_read_iter include/linux/fs.h:1897 [inline]
 new_sync_read+0x110/0x190 fs/read_write.c:415
 vfs_read+0x118/0x1b0 fs/read_write.c:496
 ksys_read+0x5a/0xd0 fs/read_write.c:634
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fe8f3985210
Code: 73 01 c3 48 8b 0d 98 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d b9 c1 20 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 4e fc ff ff 48 89 04 24
RSP: 002b:00007fff22816bf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000055dc5bc15530 RCX: 00007fe8f3985210
RDX: 0000000000000400 RSI: 000055dc5bc15558 RDI: 000000000000000f
RBP: 000055dc5bc029c0 R08: 00007fe8f396ff68 R09: 0000000000000430
R10: 000000000000006d R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000400 R14: 000055dc5bc02a10 R15: 0000000000000400
Modules linked in:
CR2: 0000000000000130
---[ end trace a7acf5d23723d15e ]---
RIP: 0010:bdev_read_page+0xa/0xa0 fs/block_dev.c:719
Code: 48 8b 38 48 81 ef d8 01 00 00 e8 b1 fe ff ff 31 c0 c3 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 41 55 41 54 55 53 48 83 ec 08 <48> 8b 87 30 01 00 00 4c 8b a8 e0 05 00 00 49 83 7d 18 00 74 75 48
RSP: 0018:ffffc90002a57ad0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000014
RDX: ffffea0004791380 RSI: a000479138000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 000000000000001d
R13: 0000000000000000 R14: a000479138000000 R15: ffffc90002a57bc0
FS:  00007fe8f483e8c0(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f7cf53000 CR3: 000000011d780000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400