================================================================== BUG: KCSAN: data-race in __delayacct_blkio_end / __delayacct_blkio_start write to 0xffff88812ae3fd78 of 8 bytes by task 23336 on cpu 0: __delayacct_blkio_start+0x35/0x40 kernel/delayacct.c:61 delayacct_blkio_start include/linux/delayacct.h:119 [inline] __schedule+0x18d/0x560 kernel/sched/core.c:4117 schedule+0x91/0xd0 kernel/sched/core.c:4230 io_schedule+0x3b/0x50 kernel/sched/core.c:5873 wait_on_page_bit_common+0x458/0x710 mm/filemap.c:1150 __lock_page+0x5f/0x70 mm/filemap.c:1358 lock_page include/linux/pagemap.h:521 [inline] mpage_prepare_extent_to_map+0x2cd/0x600 fs/ext4/inode.c:2582 ext4_writepages+0x7e2/0x1cb0 fs/ext4/inode.c:2736 do_writepages+0x7b/0x150 mm/page-writeback.c:2354 __filemap_fdatawrite_range+0x19b/0x1d0 mm/filemap.c:421 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:760 ext4_sync_file+0xe2/0x680 fs/ext4/fsync.c:151 vfs_fsync_range+0x107/0x120 fs/sync.c:200 generic_write_sync include/linux/fs.h:2884 [inline] ext4_buffered_write_iter+0x34e/0x390 fs/ext4/file.c:277 ext4_file_write_iter+0x4a3/0xfd0 fs/ext4/file.c:498 call_write_iter include/linux/fs.h:1907 [inline] do_iter_readv_writev+0x321/0x3c0 fs/read_write.c:694 do_iter_write+0x10e/0x470 fs/read_write.c:999 vfs_iter_write+0x4c/0x70 fs/read_write.c:1040 ovl_write_iter+0x48f/0x600 fs/overlayfs/file.c:350 call_write_iter include/linux/fs.h:1907 [inline] new_sync_write fs/read_write.c:484 [inline] __vfs_write+0x2d8/0x340 fs/read_write.c:497 vfs_write+0x19b/0x350 fs/read_write.c:559 ksys_write+0xce/0x180 fs/read_write.c:612 __do_sys_write fs/read_write.c:624 [inline] __se_sys_write fs/read_write.c:621 [inline] __x64_sys_write+0x3e/0x50 fs/read_write.c:621 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffff88812ae3fd78 of 8 bytes by task 21 on cpu 1: delayacct_end kernel/delayacct.c:48 [inline] __delayacct_blkio_end+0x70/0x100 kernel/delayacct.c:82 delayacct_blkio_end include/linux/delayacct.h:125 [inline] try_to_wake_up+0x126/0x5a0 kernel/sched/core.c:2582 autoremove_wake_function+0xc/0x50 kernel/sched/wait.c:389 wake_page_function+0xb5/0xe0 mm/filemap.c:1027 __wake_up_common+0xbc/0x130 kernel/sched/wait.c:93 wake_up_page_bit+0xa4/0x190 mm/filemap.c:1047 unlock_page+0x5e/0x70 mm/filemap.c:1292 ext4_bio_write_page+0xb81/0xcd0 fs/ext4/page-io.c:557 mpage_submit_page+0xf4/0x170 fs/ext4/inode.c:2082 mpage_map_and_submit_buffers fs/ext4/inode.c:2330 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2469 [inline] ext4_writepages+0x106b/0x1cb0 fs/ext4/inode.c:2782 do_writepages+0x7b/0x150 mm/page-writeback.c:2354 __writeback_single_inode+0x81/0x610 fs/fs-writeback.c:1452 writeback_sb_inodes+0x5b8/0xe00 fs/fs-writeback.c:1716 wb_writeback+0x2b8/0x730 fs/fs-writeback.c:1892 wb_do_writeback+0x108/0x600 fs/fs-writeback.c:2037 wb_workfn+0xb8/0x430 fs/fs-writeback.c:2078 process_one_work+0x3cb/0x990 kernel/workqueue.c:2269 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415 kthread+0x210/0x220 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 5.8.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-8:0) ==================================================================