F2FS-fs (loop2): Magic Mismatch, valid(0xf2f52010) - read(0x0)
F2FS-fs (loop2): Can't find valid F2FS filesystem in 2th superblock
F2FS-fs (loop2): invalid crc_offset: 0
BUG: kernel NULL pointer dereference, address: 000000000000004c
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 11dd15067 P4D 11dd15067 PUD 11dd16067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 8086 Comm: syz-executor.2 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:get_zone_idx fs/f2fs/segment.c:4704 [inline]
RIP: 0010:f2fs_usable_zone_blks_in_seg+0x8d/0x140 fs/f2fs/segment.c:4755
Code: 8b 83 80 0c 00 00 8b 8b 78 0c 00 00 48 8b bb 08 14 00 00 45 0f af c4 44 03 00 49 63 c1 48 6b c0 68 41 d3 e0 8b 8b 60 01 00 00 <44> 2b 44 07 4c 41 01 d0 44 89 ca 41 d3 e8 44 89 c6 e8 0d ff ff ff
RSP: 0018:ffffc90002057bb8 EFLAGS: 00010206
RAX: 0000000000000000 RBX: ffff88810e810000 RCX: 0000000000000000
RDX: 0000000000000200 RSI: 0000000000001000 RDI: 0000000000000000
RBP: 0000000000001000 R08: 0000000000000e00 R09: 0000000000000000
R10: ffff88810f7b6400 R11: e6e132e01efb9d1b R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810e810000
FS:  00007f9b1801c700(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000004c CR3: 000000011dd14000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 f2fs_usable_blks_in_seg fs/f2fs/segment.c:4811 [inline]
 check_block_count+0x15b/0x170 fs/f2fs/segment.h:682
 build_sit_entries fs/f2fs/segment.c:4217 [inline]
 f2fs_build_segment_manager+0x12f7/0x2500 fs/f2fs/segment.c:4911
 f2fs_fill_super+0xfc1/0x1f50 fs/f2fs/super.c:3662
 mount_bdev+0x183/0x1b0 fs/super.c:1417
 legacy_get_tree+0x28/0x50 fs/fs_context.c:592
 vfs_get_tree+0x1d/0xb0 fs/super.c:1547
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x6e9/0xa60 fs/namespace.c:3192
 do_mount+0x70/0x90 fs/namespace.c:3205
 __do_sys_mount fs/namespace.c:3413 [inline]
 __se_sys_mount fs/namespace.c:3390 [inline]
 __x64_sys_mount+0xbf/0xe0 fs/namespace.c:3390
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x46004a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 fd 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 da 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f9b1801ba88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f9b1801bb20 RCX: 000000000046004a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f9b1801bae0
RBP: 00007f9b1801bae0 R08: 00007f9b1801bb20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020015000
Modules linked in:
CR2: 000000000000004c
---[ end trace d54e08f4bbb744f1 ]---
RIP: 0010:get_zone_idx fs/f2fs/segment.c:4704 [inline]
RIP: 0010:f2fs_usable_zone_blks_in_seg+0x8d/0x140 fs/f2fs/segment.c:4755
Code: 8b 83 80 0c 00 00 8b 8b 78 0c 00 00 48 8b bb 08 14 00 00 45 0f af c4 44 03 00 49 63 c1 48 6b c0 68 41 d3 e0 8b 8b 60 01 00 00 <44> 2b 44 07 4c 41 01 d0 44 89 ca 41 d3 e8 44 89 c6 e8 0d ff ff ff
RSP: 0018:ffffc90002057bb8 EFLAGS: 00010206
RAX: 0000000000000000 RBX: ffff88810e810000 RCX: 0000000000000000
RDX: 0000000000000200 RSI: 0000000000001000 RDI: 0000000000000000
RBP: 0000000000001000 R08: 0000000000000e00 R09: 0000000000000000
R10: ffff88810f7b6400 R11: e6e132e01efb9d1b R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810e810000
FS:  00007f9b1801c700(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f120310c6c8 CR3: 000000011dd14000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400