syzbot

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BUG: KCSAN: data-race in __add_to_page_cache_locked / filemap_write_and_wait

read to 0xffff8881245bb330 of 8 bytes by task 9443 on cpu 1:
 mapping_needs_writeback mm/filemap.c:631 [inline]
 filemap_write_and_wait+0x65/0x150 mm/filemap.c:638
 ext4_ioctl_get_es_cache fs/ext4/ioctl.c:805 [inline]
 ext4_ioctl+0x2574/0x3130 fs/ext4/ioctl.c:1238
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x991/0xc60 fs/ioctl.c:696
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:718
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8881245bb330 of 8 bytes by task 9441 on cpu 0:
 __add_to_page_cache_locked+0x298/0x780 mm/filemap.c:889
 add_to_page_cache_lru+0xe2/0x2d0 mm/filemap.c:942
 pagecache_get_page+0x2ab/0x760 mm/filemap.c:1681
 grab_cache_page_write_begin+0x5d/0x90 mm/filemap.c:3254
 ext4_da_write_begin+0x175/0x7e0 fs/ext4/inode.c:3063
 generic_perform_write+0x136/0x320 mm/filemap.c:3304
 __generic_file_write_iter+0x251/0x380 mm/filemap.c:3433
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9441 Comm: syz-executor.5 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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