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BUG: KCSAN: data-race in __mark_inode_dirty / writeback_sb_inodes

write to 0xffff88811dc41340 of 8 bytes by task 8376 on cpu 1:
 writeback_sb_inodes+0x3b7/0xe00 fs/fs-writeback.c:1705
 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

read to 0xffff88811dc41340 of 8 bytes by task 11567 on cpu 0:
 __mark_inode_dirty+0xb9/0x7d0 fs/fs-writeback.c:2272
 mark_inode_dirty include/linux/fs.h:2192 [inline]
 dquot_alloc_space include/linux/quotaops.h:320 [inline]
 dquot_alloc_block include/linux/quotaops.h:337 [inline]
 ext4_mb_new_blocks+0x7c8/0xcf0 fs/ext4/mballoc.c:4683
 ext4_ext_map_blocks+0x164e/0x20c0 fs/ext4/extents.c:4244
 ext4_map_blocks+0x6a6/0xf60 fs/ext4/inode.c:626
 ext4_alloc_file_blocks+0x24e/0x6d0 fs/ext4/extents.c:4433
 ext4_fallocate+0x265/0x550 fs/ext4/extents.c:4702
 vfs_fallocate+0x431/0x580 fs/open.c:309
 file_ioctl fs/ioctl.c:494 [inline]
 do_vfs_ioctl+0xde0/0xec0 fs/ioctl.c:732
 ksys_ioctl fs/ioctl.c:751 [inline]
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl+0x81/0x130 fs/ioctl.c:760
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:760
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11567 Comm: syz-executor.4 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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