KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync

Kernel	Title	Rank 🛈	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync_noflush (3) ext4	6	1	110d	110d	0/29	auto-obsoleted due to no activity on 2025/08/09 08:40
upstream	KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync_noflush ext4	6	2	372d	383d	0/29	auto-obsoleted due to no activity on 2024/10/29 23:12
upstream	KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync_noflush (2) ext4	6	3	237d	300d	0/29	auto-obsoleted due to no activity on 2025/04/04 01:26

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BUG: KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync_noflush

write to 0xffff88811a0c0ea8 of 4 bytes by task 8388 on cpu 1:
 __mark_inode_dirty+0x248/0x750 fs/fs-writeback.c:2597
 ext4_mb_new_blocks+0x10b9/0x2080 fs/ext4/mballoc.c:-1
 ext4_alloc_branch fs/ext4/indirect.c:340 [inline]
 ext4_ind_map_blocks+0xb86/0x14f0 fs/ext4/indirect.c:635
 ext4_map_create_blocks fs/ext4/inode.c:611 [inline]
 ext4_map_blocks+0x598/0xd00 fs/ext4/inode.c:811
 _ext4_get_block+0x10a/0x350 fs/ext4/inode.c:910
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:927
 ext4_block_write_begin+0x5e5/0xc00 fs/ext4/inode.c:1198
 ext4_write_begin+0x647/0xeb0 fs/ext4/ext4_jbd2.h:-1
 generic_perform_write+0x184/0x490 mm/filemap.c:4175
 ext4_buffered_write_iter+0x1ee/0x3c0 fs/ext4/file.c:299
 ext4_dio_write_iter fs/ext4/file.c:613 [inline]
 ext4_file_write_iter+0xdbf/0xf00 fs/ext4/file.c:721
 iter_file_splice_write+0x663/0xa60 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x153/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x30f/0x680 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a0c0ea8 of 4 bytes by task 8395 on cpu 0:
 generic_buffers_fsync_noflush+0x80/0x120 fs/buffer.c:614
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1ab/0x690 fs/ext4/fsync.c:147
 vfs_fsync_range+0x10d/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:3036 [inline]
 ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
 ext4_dio_write_iter fs/ext4/file.c:613 [inline]
 ext4_file_write_iter+0xdbf/0xf00 fs/ext4/file.c:721
 iter_file_splice_write+0x663/0xa60 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x153/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x30f/0x680 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000040 -> 0x00000070

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8395 Comm: syz.0.2121 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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