jfs_dirty_inode called on read-only volume
Is remount racy?
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BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: null-ptr-deref in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: null-ptr-deref in txBeginAnon+0x19a/0x4b0 fs/jfs/jfs_txnmgr.c:465
Read of size 8 at addr 0000000000000040 by task syz.1.1770/22851

CPU: 0 UID: 0 PID: 22851 Comm: syz.1.1770 Not tainted 6.11.0-rc7-syzkaller-00020-g8d8d276ba2fb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_report+0xe8/0x550 mm/kasan/report.c:491
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 txBeginAnon+0x19a/0x4b0 fs/jfs/jfs_txnmgr.c:465
 extAlloc+0xf5/0x1010 fs/jfs/jfs_extent.c:78
 jfs_get_block+0x41b/0xe60 fs/jfs/inode.c:248
 __block_write_begin_int+0x50c/0x1a70 fs/buffer.c:2125
 __block_write_begin fs/buffer.c:2174 [inline]
 block_write_begin+0x9b/0x1e0 fs/buffer.c:2235
 jfs_write_begin+0x31/0x70 fs/jfs/inode.c:299
 generic_perform_write+0x399/0x840 mm/filemap.c:4019
 generic_file_write_iter+0xaf/0x310 mm/filemap.c:4147
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa72/0xc90 fs/read_write.c:590
 ksys_pwrite64 fs/read_write.c:705 [inline]
 __do_sys_pwrite64 fs/read_write.c:715 [inline]
 __se_sys_pwrite64 fs/read_write.c:712 [inline]
 __x64_sys_pwrite64+0x1aa/0x230 fs/read_write.c:712
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa95d97def9
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:00007fa95e7c5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fa95db35f80 RCX: 00007fa95d97def9
RDX: 0000000000000001 RSI: 0000000020003a80 RDI: 000000000000000e
RBP: 00007fa95d9f09f6 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa95db35f80 R15: 00007ffd4a647008
 </TASK>
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