================================================================== BUG: KCSAN: data-race in copy_page_to_iter / fat16_ent_put write to 0xffff88811818e80a of 2 bytes by task 18164 on cpu 1: fat16_ent_put+0x24/0x50 fs/fat/fatent.c:181 fat_alloc_clusters+0x430/0xa60 fs/fat/fatent.c:501 fat_add_cluster fs/fat/inode.c:108 [inline] __fat_get_block fs/fat/inode.c:155 [inline] fat_get_block+0x213/0x5a0 fs/fat/inode.c:190 __block_write_begin_int+0x4bf/0xfd0 fs/buffer.c:2012 __block_write_begin fs/buffer.c:2062 [inline] block_write_begin+0x4f/0x190 fs/buffer.c:2121 cont_write_begin+0x42c/0x610 fs/buffer.c:2470 fat_write_begin+0x61/0xf0 fs/fat/inode.c:235 pagecache_write_begin+0x54/0x70 mm/filemap.c:3118 cont_expand_zero fs/buffer.c:2397 [inline] cont_write_begin+0x13f/0x610 fs/buffer.c:2460 fat_write_begin+0x61/0xf0 fs/fat/inode.c:235 pagecache_write_begin+0x54/0x70 mm/filemap.c:3118 generic_cont_expand_simple+0x6d/0x100 fs/buffer.c:2361 fat_cont_expand+0x3a/0x160 fs/fat/file.c:222 fat_fallocate+0x180/0x1d0 fs/fat/file.c:300 vfs_fallocate+0x431/0x580 fs/open.c:309 ksys_fallocate fs/open.c:332 [inline] __do_sys_fallocate fs/open.c:340 [inline] __se_sys_fallocate fs/open.c:338 [inline] __x64_sys_fallocate+0x75/0xc0 fs/open.c:338 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffff88811818e000 of 4096 bytes by task 18149 on cpu 0: instrument_copy_to_user include/linux/instrumented.h:89 [inline] copyout lib/iov_iter.c:142 [inline] copy_page_to_iter_iovec lib/iov_iter.c:212 [inline] copy_page_to_iter+0x346/0x8a0 lib/iov_iter.c:921 generic_file_buffered_read+0x1075/0x1800 mm/filemap.c:2126 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2307 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:2044 call_read_iter include/linux/fs.h:1901 [inline] new_sync_read fs/read_write.c:415 [inline] __vfs_read+0x2d5/0x330 fs/read_write.c:428 vfs_read+0x131/0x2a0 fs/read_write.c:462 ksys_read+0xce/0x180 fs/read_write.c:588 __do_sys_read fs/read_write.c:598 [inline] __se_sys_read fs/read_write.c:596 [inline] __x64_sys_read+0x3e/0x50 fs/read_write.c:596 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 18149 Comm: systemd-udevd Not tainted 5.8.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================