==================================================================
BUG: KCSAN: data-race in __mark_inode_dirty / writeback_sb_inodes

write to 0xffff88811ede9a80 of 8 bytes by task 7 on cpu 1:
 writeback_sb_inodes+0x3a7/0xe40 fs/fs-writeback.c:1705
 wb_writeback+0x2b8/0x730 fs/fs-writeback.c:1892
 wb_do_writeback+0x108/0x610 fs/fs-writeback.c:2037
 wb_workfn+0xc8/0x460 fs/fs-writeback.c:2078
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88811ede9a80 of 8 bytes by task 27839 on cpu 0:
 __mark_inode_dirty+0xb9/0x7e0 fs/fs-writeback.c:2272
 generic_update_time fs/inode.c:1762 [inline]
 update_time fs/inode.c:1775 [inline]
 file_update_time+0x3a8/0x3f0 fs/inode.c:1990
 ext4_page_mkwrite+0xe3/0xae0 fs/ext4/inode.c:5972
 do_page_mkwrite mm/memory.c:2530 [inline]
 do_shared_fault+0x21e/0x770 mm/memory.c:3924
 do_fault mm/memory.c:3992 [inline]
 handle_pte_fault mm/memory.c:4228 [inline]
 __handle_mm_fault mm/memory.c:4360 [inline]
 handle_mm_fault+0x158a/0x1950 mm/memory.c:4397
 do_user_addr_fault+0x393/0x810 arch/x86/mm/fault.c:1294
 handle_page_fault arch/x86/mm/fault.c:1364 [inline]
 exc_page_fault+0xb8/0x330 arch/x86/mm/fault.c:1417
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:538

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 27839 Comm: syz-executor.3 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================