KCSAN: data-race in __wb_calc_thresh / __wb_update

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __wb_calc_thresh / __wb_update_bandwidth fs mm				3	1628d	1640d	0/26	closed as invalid on 2019/11/19 13:44

================================================================== BUG: KCSAN: data-race in __wb_calc_thresh / __wb_update_bandwidth read to 0xffff8880a3d15928 of 8 bytes by task 15112 on cpu 1: __wb_calc_thresh+0xdc/0x250 mm/page-writeback.c:782 wb_calc_thresh+0x96/0xc0 mm/page-writeback.c:795 wb_over_bg_thresh+0x287/0x490 mm/page-writeback.c:1949 wb_check_background_flush fs/fs-writeback.c:1952 [inline] wb_do_writeback fs/fs-writeback.c:2050 [inline] wb_workfn+0x3b3/0x970 fs/fs-writeback.c:2078 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 worker_thread+0xa0/0x800 kernel/workqueue.c:2415 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 write to 0xffff8880a3d15928 of 8 bytes by task 13485 on cpu 0: wb_update_write_bandwidth mm/page-writeback.c:1130 [inline] __wb_update_bandwidth+0x277/0x3c0 mm/page-writeback.c:1387 balance_dirty_pages+0x10d5/0x1ba0 mm/page-writeback.c:1709 balance_dirty_pages_ratelimited+0x752/0xb40 mm/page-writeback.c:1913 generic_perform_write+0x22d/0x320 mm/filemap.c:3341 __generic_file_write_iter+0x251/0x380 mm/filemap.c:3434 ext4_file_write_iter+0x1bd/0xa00 fs/ext4/file.c:268 call_write_iter include/linux/fs.h:1895 [inline] new_sync_write+0x388/0x4a0 fs/read_write.c:483 __vfs_write+0xb1/0xc0 fs/read_write.c:496 vfs_write fs/read_write.c:558 [inline] vfs_write+0x18a/0x390 fs/read_write.c:542 ksys_write+0xd5/0x1b0 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x4c/0x60 fs/read_write.c:620 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 13485 Comm: syz-executor.2 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================