================================================================== BUG: KCSAN: data-race in copy_page_to_iter / ext4_fill_super write to 0xffff8881383b040c of 4 bytes by task 20754 on cpu 0: ext4_free_blocks_count_set fs/ext4/ext4.h:3323 [inline] ext4_fill_super+0x692c/0x7830 fs/ext4/super.c:4885 mount_bdev+0x1e8/0x290 fs/super.c:1368 ext4_mount+0x2d/0x40 fs/ext4/super.c:6515 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610 vfs_get_tree+0x4a/0x1a0 fs/super.c:1498 do_new_mount fs/namespace.c:2988 [inline] path_mount+0x11ec/0x1d20 fs/namespace.c:3318 do_mount fs/namespace.c:3331 [inline] __do_sys_mount fs/namespace.c:3539 [inline] __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3516 __x64_sys_mount+0x63/0x70 fs/namespace.c:3516 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff8881383b0000 of 1377 bytes by task 20729 on cpu 1: instrument_copy_to_user include/linux/instrumented.h:119 [inline] copyout lib/iov_iter.c:156 [inline] copy_page_to_iter_iovec lib/iov_iter.c:228 [inline] __copy_page_to_iter lib/iov_iter.c:805 [inline] copy_page_to_iter+0x2cb/0x950 lib/iov_iter.c:833 filemap_read+0xee6/0x1220 mm/filemap.c:2683 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2779 blkdev_read_iter+0xb9/0xf0 block/fops.c:545 call_read_iter include/linux/fs.h:2157 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0x66c/0x750 fs/read_write.c:485 ksys_read+0xd9/0x190 fs/read_write.c:623 __do_sys_read fs/read_write.c:633 [inline] __se_sys_read fs/read_write.c:631 [inline] __x64_sys_read+0x3e/0x50 fs/read_write.c:631 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 20729 Comm: systemd-udevd Not tainted 5.15.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================