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BUG: KCSAN: data-race in __mark_inode_dirty / writeback_sb_inodes

write to 0xffff8881069df298 of 8 bytes by task 1783 on cpu 0:
 writeback_sb_inodes+0x3cc/0xf10 fs/fs-writeback.c:1721
 wb_writeback+0x28e/0x700 fs/fs-writeback.c:1905
 wb_do_writeback+0x101/0x510 fs/fs-writeback.c:2050
 wb_workfn+0xc8/0x520 fs/fs-writeback.c:2091
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x1d0/0x1f0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff8881069df298 of 8 bytes by task 16245 on cpu 1:
 __mark_inode_dirty+0xda/0x6c0 fs/fs-writeback.c:2295
 mark_inode_dirty_sync include/linux/fs.h:2409 [inline]
 dquot_free_space include/linux/quotaops.h:382 [inline]
 dquot_free_block include/linux/quotaops.h:392 [inline]
 ext4_mb_new_blocks+0x16cc/0x1f90 fs/ext4/mballoc.c:5562
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4241
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4428
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4708
 vfs_fallocate+0x463/0x660 fs/open.c:311
 file_ioctl fs/ioctl.c:497 [inline]
 do_vfs_ioctl+0x1322/0x1410 fs/ioctl.c:1048
 __do_sys_ioctl fs/ioctl.c:1067 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000020007 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16245 Comm: syz-executor.4 Not tainted 5.13.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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