EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback. EXT4-fs error (device loop0): ext4_read_block_bitmap_nowait:478: comm syz.0.815: Invalid block bitmap block 0 in block_group 0 BUG: unable to handle page fault for address: ffffffffffffff93 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD cf35067 P4D cf35067 PUD cf37067 PMD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 8854 Comm: syz.0.815 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline] RIP: 0010:ext4_free_ext_path fs/ext4/extents.c:128 [inline] RIP: 0010:ext4_ext_map_blocks+0x2d00/0x6800 fs/ext4/extents.c:4494 Code: 8b 7c 24 10 4d 85 ff 0f 84 bd 00 00 00 e8 78 dc 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 3d 1e 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 10 4d 89 fc 49 8d RSP: 0018:ffffc90003786d60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000021 RCX: 0000000000080000 RDX: ffffc9000cb2a000 RSI: 00000000000225d6 RDI: ffffffffffffff93 RBP: ffffc90003787010 R08: ffffffff911c369f R09: 1ffffffff22386d3 R10: dffffc0000000000 R11: fffffbfff22386d4 R12: 0000000000000001 R13: 1ffff920006f0dd8 R14: dffffc0000000000 R15: ffffffffffffff8b FS: 00007f8275ae06c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffff93 CR3: 000000002dd84000 CR4: 00000000003506e0 Call Trace: ext4_map_blocks+0x9e2/0x1b80 fs/ext4/inode.c:652 ext4_getblk+0x1d0/0x6f0 fs/ext4/inode.c:862 ext4_bread+0x2a/0x170 fs/ext4/inode.c:918 ext4_quota_write+0x23a/0x580 fs/ext4/super.c:7313 write_blk+0x115/0x220 fs/quota/quota_tree.c:70 do_insert_tree+0xad2/0x10a0 fs/quota/quota_tree.c:407 dq_insert_tree fs/quota/quota_tree.c:432 [inline] qtree_write_dquot+0x4a1/0x5d0 fs/quota/quota_tree.c:451 v2_write_dquot+0x10c/0x1a0 fs/quota/quota_v2.c:361 dquot_acquire+0x320/0x610 fs/quota/dquot.c:474 ext4_acquire_dquot+0x2e3/0x4b0 fs/ext4/super.c:6945 dqget+0x77c/0xeb0 fs/quota/dquot.c:990 __dquot_initialize+0x3c7/0xcd0 fs/quota/dquot.c:1518 ext4_create+0x96/0x470 fs/ext4/namei.c:2876 lookup_open fs/namei.c:3496 [inline] open_last_lookups fs/namei.c:3564 [inline] path_openat+0x12a0/0x3230 fs/namei.c:3794 do_filp_open+0x1f5/0x430 fs/namei.c:3824 do_sys_openat2+0x134/0x1d0 fs/open.c:1421 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1447 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f8274b9c819 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:00007f8275ae0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f8274e15fa0 RCX: 00007f8274b9c819 RDX: 00000000000026e1 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007f8274c32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8274e16038 R14: 00007f8274e15fa0 R15: 00007ffe93f86ec8 Modules linked in: CR2: ffffffffffffff93 ---[ end trace 0000000000000000 ]--- RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline] RIP: 0010:ext4_free_ext_path fs/ext4/extents.c:128 [inline] RIP: 0010:ext4_ext_map_blocks+0x2d00/0x6800 fs/ext4/extents.c:4494 Code: 8b 7c 24 10 4d 85 ff 0f 84 bd 00 00 00 e8 78 dc 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 3d 1e 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 10 4d 89 fc 49 8d RSP: 0018:ffffc90003786d60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000021 RCX: 0000000000080000 RDX: ffffc9000cb2a000 RSI: 00000000000225d6 RDI: ffffffffffffff93 RBP: ffffc90003787010 R08: ffffffff911c369f R09: 1ffffffff22386d3 R10: dffffc0000000000 R11: fffffbfff22386d4 R12: 0000000000000001 R13: 1ffff920006f0dd8 R14: dffffc0000000000 R15: ffffffffffffff8b FS: 00007f8275ae06c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffff93 CR3: 000000002dd84000 CR4: 00000000003506e0 ---------------- Code disassembly (best guess): 0: 8b 7c 24 10 mov 0x10(%rsp),%edi 4: 4d 85 ff test %r15,%r15 7: 0f 84 bd 00 00 00 je 0xca d: e8 78 dc 58 ff call 0xff58dc8a 12: 49 8d 7f 08 lea 0x8(%r15),%rdi 16: 48 89 f8 mov %rdi,%rax 19: 48 c1 e8 03 shr $0x3,%rax 1d: 42 0f b6 04 30 movzbl (%rax,%r14,1),%eax 22: 84 c0 test %al,%al 24: 0f 85 3d 1e 00 00 jne 0x1e67 * 2a: 41 0f b7 47 08 movzwl 0x8(%r15),%eax <-- trapping instruction 2f: c1 e0 04 shl $0x4,%eax 32: 48 8d 04 40 lea (%rax,%rax,2),%rax 36: 48 89 44 24 10 mov %rax,0x10(%rsp) 3b: 4d 89 fc mov %r15,%r12 3e: 49 rex.WB 3f: 8d .byte 0x8d