================================================================== BUG: KCSAN: data-race in fat16_ent_put / fat_mirror_bhs write to 0xffff888107c04764 of 2 bytes by task 4645 on cpu 1: fat16_ent_put+0x28/0x60 fs/fat/fatent.c:183 fat_free_clusters+0x2a6/0x790 fs/fat/fatent.c:597 fat_free fs/fat/file.c:376 [inline] fat_truncate_blocks+0x4c2/0x550 fs/fat/file.c:394 fat_write_failed fs/fat/inode.c:218 [inline] fat_write_end+0xba/0x160 fs/fat/inode.c:246 generic_perform_write+0x30f/0x490 mm/filemap.c:4162 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4258 generic_file_write_iter+0x8d/0x2f0 mm/filemap.c:4284 do_iter_readv_writev+0x41e/0x4c0 fs/read_write.c:-1 vfs_writev+0x2df/0x8b0 fs/read_write.c:1057 do_pwritev fs/read_write.c:1153 [inline] __do_sys_pwritev2 fs/read_write.c:1211 [inline] __se_sys_pwritev2+0xfc/0x1c0 fs/read_write.c:1202 __x64_sys_pwritev2+0x67/0x80 fs/read_write.c:1202 x64_sys_call+0x2c55/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:329 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 0xffff888107c04600 of 512 bytes by task 4644 on cpu 0: fat_mirror_bhs+0x1df/0x320 fs/fat/fatent.c:395 fat_ent_write+0xd0/0xe0 fs/fat/fatent.c:423 fat_chain_add+0x15b/0x3f0 fs/fat/misc.c:136 fat_add_cluster fs/fat/inode.c:112 [inline] __fat_get_block fs/fat/inode.c:154 [inline] fat_get_block+0x46c/0x5e0 fs/fat/inode.c:189 __block_write_begin_int+0x400/0xf90 fs/buffer.c:2145 block_write_begin fs/buffer.c:2256 [inline] cont_write_begin+0x5fc/0x970 fs/buffer.c:2594 fat_write_begin+0x4f/0xe0 fs/fat/inode.c:229 cont_expand_zero fs/buffer.c:2522 [inline] cont_write_begin+0x1b0/0x970 fs/buffer.c:2584 fat_write_begin+0x4f/0xe0 fs/fat/inode.c:229 generic_cont_expand_simple+0xad/0x150 fs/buffer.c:2485 fat_cont_expand+0x3e/0x170 fs/fat/file.c:223 fat_setattr+0x2a5/0x8a0 fs/fat/file.c:513 notify_change+0x806/0x890 fs/attr.c:552 do_truncate fs/open.c:68 [inline] do_ftruncate+0x34b/0x450 fs/open.c:195 do_sys_ftruncate fs/open.c:210 [inline] __do_sys_ftruncate fs/open.c:215 [inline] __se_sys_ftruncate fs/open.c:213 [inline] __x64_sys_ftruncate+0x68/0xc0 fs/open.c:213 x64_sys_call+0x2d52/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:78 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 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 4644 Comm: syz.2.370 Not tainted 6.16.0-syzkaller-01056-gae388edd4a8f #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 ==================================================================