loop0: detected capacity change from 0 to 32768
BUG at fs/jfs/jfs_dmap.c:2983 assert(n < 4)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_dmap.c:2983!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5315 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:dbFindLeaf+0x51d/0x520 fs/jfs/jfs_dmap.c:2983
Code: e9 4c ff ff ff e8 e3 37 69 fe 48 c7 c7 a0 28 0b 8c 48 c7 c6 e0 25 0b 8c ba a7 0b 00 00 48 c7 c1 c0 33 0b 8c e8 a4 5a cb fd 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57
RSP: 0018:ffffc9000f16faa0 EFLAGS: 00010246
RAX: 000000000000002b RBX: 0000000000000000 RCX: 0c808d10a9edce00
RDX: ffffc90020001000 RSI: 0000000000000f2c RDI: 0000000000000f2d
RBP: 0000000000000003 R08: ffffc9000f16f827 R09: 1ffff92001e2df04
R10: dffffc0000000000 R11: fffff52001e2df05 R12: 000000000000000a
R13: 0000000000000008 R14: 0000000000000005 R15: 0000000000000155
FS:  00007f0fd68326c0(0000) GS:ffff88808ca5b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffccadff74 CR3: 0000000044981000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dbAllocDmapLev+0x60/0x3c0 fs/jfs/jfs_dmap.c:1969
 dbAllocCtl+0x14a/0x9c0 fs/jfs/jfs_dmap.c:1825
 dbAllocAG+0xc2b/0xff0 fs/jfs/jfs_dmap.c:1472
 dbDiscardAG+0x2da/0x8f0 fs/jfs/jfs_dmap.c:1608
 jfs_ioc_trim+0x429/0x690 fs/jfs/jfs_discard.c:106
 jfs_ioctl+0x28e/0x3b0 fs/jfs/ioctl.c:131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0fd599c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0fd6832028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f0fd5c15fa0 RCX: 00007f0fd599c629
RDX: 0000200000000180 RSI: 00000000c0185879 RDI: 000000000000000b
RBP: 00007f0fd5a32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0fd5c16038 R14: 00007f0fd5c15fa0 R15: 00007ffc2336e4a8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbFindLeaf+0x51d/0x520 fs/jfs/jfs_dmap.c:2983
Code: e9 4c ff ff ff e8 e3 37 69 fe 48 c7 c7 a0 28 0b 8c 48 c7 c6 e0 25 0b 8c ba a7 0b 00 00 48 c7 c1 c0 33 0b 8c e8 a4 5a cb fd 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57
RSP: 0018:ffffc9000f16faa0 EFLAGS: 00010246
RAX: 000000000000002b RBX: 0000000000000000 RCX: 0c808d10a9edce00
RDX: ffffc90020001000 RSI: 0000000000000f2c RDI: 0000000000000f2d
RBP: 0000000000000003 R08: ffffc9000f16f827 R09: 1ffff92001e2df04
R10: dffffc0000000000 R11: fffff52001e2df05 R12: 000000000000000a
R13: 0000000000000008 R14: 0000000000000005 R15: 0000000000000155
FS:  00007f0fd68326c0(0000) GS:ffff88808ca5b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0fd6810ff0 CR3: 0000000044981000 CR4: 0000000000352ef0