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BUG: KCSAN: data-race in __mark_inode_dirty / __mark_inode_dirty

write to 0xffff888105ac3a28 of 4 bytes by task 6877 on cpu 0:
 __mark_inode_dirty+0x24e/0x7e0 fs/fs-writeback.c:2546
 mark_buffer_dirty+0x149/0x230 fs/buffer.c:1199
 __block_commit_write fs/buffer.c:2189 [inline]
 block_write_end+0x123/0x210 fs/buffer.c:2265
 generic_write_end+0x5c/0x160 fs/buffer.c:2279
 fat_write_end+0x4e/0x160 fs/fat/inode.c:242
 generic_perform_write+0x33c/0x4a0 mm/filemap.c:4070
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4156
 generic_file_write_iter+0x77/0x1c0 mm/filemap.c:4182
 iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x398/0x660 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
 x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105ac3a28 of 4 bytes by task 6878 on cpu 1:
 __mark_inode_dirty+0x58/0x7e0 fs/fs-writeback.c:2497
 fat_update_time+0x1e8/0x200 fs/fat/misc.c:357
 inode_update_time fs/inode.c:2124 [inline]
 touch_atime+0x14f/0x350 fs/inode.c:2197
 file_accessed include/linux/fs.h:2539 [inline]
 filemap_splice_read+0x8a5/0x910 mm/filemap.c:2978
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x269/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x398/0x660 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
 x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000008 -> 0x00000038

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6878 Comm: syz.3.1316 Not tainted 6.12.0-syzkaller-09073-g9f16d5e6f220 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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