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BUG: KCSAN: data-race in __mark_inode_dirty / __mark_inode_dirty

write to 0xffff888120846528 of 4 bytes by task 8821 on cpu 0:
 __mark_inode_dirty+0x240/0x760 fs/fs-writeback.c:2558
 mark_buffer_dirty+0x133/0x210 fs/buffer.c:1212
 block_commit_write fs/buffer.c:2224 [inline]
 block_write_end+0x12e/0x210 fs/buffer.c:2301
 generic_write_end+0x57/0x150 fs/buffer.c:2315
 fat_write_end+0x4f/0x160 fs/fat/inode.c:242
 generic_perform_write+0x30f/0x490 mm/filemap.c:4124
 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4220
 generic_file_write_iter+0x8d/0x2f0 mm/filemap.c:4246
 iter_file_splice_write+0x5ef/0x970 fs/splice.c:738
 do_splice_from fs/splice.c:935 [inline]
 direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
 splice_direct_to_actor+0x30f/0x680 fs/splice.c:1102
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x640 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1415
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888120846528 of 4 bytes by task 8830 on cpu 1:
 __mark_inode_dirty+0x52/0x760 fs/fs-writeback.c:2509
 fat_update_time+0x1ec/0x200 fs/fat/misc.c:357
 inode_update_time fs/inode.c:2076 [inline]
 touch_atime+0x145/0x330 fs/inode.c:2149
 file_accessed include/linux/fs.h:2599 [inline]
 filemap_splice_read+0x629/0x6b0 mm/filemap.c:3037
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x640 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1415
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000008 -> 0x00000038

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8830 Comm: syz.1.1789 Not tainted 6.15.0-rc5-syzkaller-00022-g01f95500a162 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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