Is remount racy?
jfs_dirty_inode called on read-only volume
Is remount racy?
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
BUG: KASAN: null-ptr-deref in txBeginAnon+0xa0/0x150 fs/jfs/jfs_txnmgr.c:465
Read of size 8 at addr 0000000000000040 by task syz.2.43/4515

CPU: 0 PID: 4515 Comm: syz.2.43 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 __kasan_report mm/kasan/report.c:438 [inline]
 kasan_report+0xd5/0x130 mm/kasan/report.c:451
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
 txBeginAnon+0xa0/0x150 fs/jfs/jfs_txnmgr.c:465
 extAlloc+0xf3/0xf30 fs/jfs/jfs_extent.c:81
 jfs_get_block+0x343/0xab0 fs/jfs/inode.c:258
 nobh_write_begin+0x3d5/0xe80 fs/buffer.c:2650
 jfs_write_begin+0x3d/0x80 fs/jfs/inode.c:322
 generic_perform_write+0x2aa/0x530 mm/filemap.c:3785
 __generic_file_write_iter+0x25f/0x4e0 mm/filemap.c:3912
 generic_file_write_iter+0xa6/0x1b0 mm/filemap.c:3944
 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
 do_iter_write+0x205/0x7b0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x204/0x340 fs/read_write.c:1025
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc482a9f929
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:00007fc480907038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007fc482cc6fa0 RCX: 00007fc482a9f929
RDX: 0000000000000001 RSI: 0000200000000000 RDI: 0000000000000005
RBP: 00007fc482b21b39 R08: 0000000000000009 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc482cc6fa0 R15: 00007ffedbf8a648
 </TASK>
==================================================================