Is remount racy? jfs_dirty_inode called on read-only volume Is remount racy? Oops: general protection fault, probably for non-canonical address 0xdffffc00000000c7: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000638-0x000000000000063f] CPU: 0 UID: 0 PID: 6706 Comm: syz.3.176 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:JFS_SBI fs/jfs/jfs_incore.h:217 [inline] RIP: 0010:txEnd+0xb4/0x530 fs/jfs/jfs_txnmgr.c:507 Code: 49 8d 5e 20 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 ec 66 db fe 41 bf 38 06 00 00 4c 03 3b 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 cd 66 db fe 49 8b 1f 48 83 c3 30 RSP: 0018:ffffc90002fa76c0 EFLAGS: 00010202 RAX: 00000000000000c7 RBX: ffffc90002709020 RCX: 0000000000000000 RDX: 0000000000000006 RSI: ffffffff8d786e5e RDI: 00000000ffffffff RBP: ffffc90002fa7950 R08: ffffffff8f7da977 R09: 1ffffffff1efb52e R10: dffffc0000000000 R11: fffffbfff1efb52f R12: ffff8880113a1a70 R13: dffffc0000000000 R14: ffffc90002709000 R15: 0000000000000638 FS: 00007ff9a86126c0(0000) GS:ffff888125ec2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff28f804e9c CR3: 0000000033556000 CR4: 00000000003526f0 Call Trace: jfs_create+0x33e/0xa80 fs/jfs/namei.c:159 lookup_open fs/namei.c:3796 [inline] open_last_lookups fs/namei.c:3895 [inline] path_openat+0x1941/0x3860 fs/namei.c:4131 do_filp_open+0x1fa/0x410 fs/namei.c:4161 do_sys_openat2+0x121/0x1c0 fs/open.c:1434 do_sys_open fs/open.c:1449 [inline] __do_sys_openat fs/open.c:1465 [inline] __se_sys_openat fs/open.c:1460 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1460 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff9a778f6c9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff9a8612038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007ff9a79e5fa0 RCX: 00007ff9a778f6c9 RDX: 000000000000275a RSI: 00002000000001c0 RDI: ffffffffffffff9c RBP: 00007ff9a7811f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff9a79e6038 R14: 00007ff9a79e5fa0 R15: 00007ffcd12398c8 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:JFS_SBI fs/jfs/jfs_incore.h:217 [inline] RIP: 0010:txEnd+0xb4/0x530 fs/jfs/jfs_txnmgr.c:507 Code: 49 8d 5e 20 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 ec 66 db fe 41 bf 38 06 00 00 4c 03 3b 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 cd 66 db fe 49 8b 1f 48 83 c3 30 RSP: 0018:ffffc90002fa76c0 EFLAGS: 00010202 RAX: 00000000000000c7 RBX: ffffc90002709020 RCX: 0000000000000000 RDX: 0000000000000006 RSI: ffffffff8d786e5e RDI: 00000000ffffffff RBP: ffffc90002fa7950 R08: ffffffff8f7da977 R09: 1ffffffff1efb52e R10: dffffc0000000000 R11: fffffbfff1efb52f R12: ffff8880113a1a70 R13: dffffc0000000000 R14: ffffc90002709000 R15: 0000000000000638 FS: 00007ff9a86126c0(0000) GS:ffff888125ec2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff28f804e9c CR3: 0000000033556000 CR4: 00000000003526f0 ---------------- Code disassembly (best guess): 0: 49 8d 5e 20 lea 0x20(%r14),%rbx 4: 48 89 d8 mov %rbx,%rax 7: 48 c1 e8 03 shr $0x3,%rax b: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 10: 74 08 je 0x1a 12: 48 89 df mov %rbx,%rdi 15: e8 ec 66 db fe call 0xfedb6706 1a: 41 bf 38 06 00 00 mov $0x638,%r15d 20: 4c 03 3b add (%rbx),%r15 23: 4c 89 f8 mov %r15,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 4c 89 ff mov %r15,%rdi 34: e8 cd 66 db fe call 0xfedb6706 39: 49 8b 1f mov (%r15),%rbx 3c: 48 83 c3 30 add $0x30,%rbx