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BUG: KCSAN: data-race in __add_to_page_cache_locked / ext4_writepages

write to 0xffff88813956ace0 of 8 bytes by task 17323 on cpu 0:
 __add_to_page_cache_locked+0x276/0x4f0 mm/filemap.c:931
 add_to_page_cache_lru+0xa0/0x1b0 mm/filemap.c:984
 pagecache_get_page+0x6ad/0x910 mm/filemap.c:1951
 grab_cache_page_write_begin+0x3f/0x70 mm/filemap.c:3724
 ext4_da_write_begin+0x323/0x570 fs/ext4/inode.c:2961
 generic_perform_write+0x1b8/0x3e0 mm/filemap.c:3770
 ext4_buffered_write_iter+0x305/0x400 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 aio_write+0x2b4/0x390 fs/aio.c:1578
 io_submit_one+0x86f/0x13b0 fs/aio.c:1880
 __do_sys_io_submit fs/aio.c:1939 [inline]
 __se_sys_io_submit+0x105/0x270 fs/aio.c:1909
 __x64_sys_io_submit+0x3f/0x50 fs/aio.c:1909
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813956ace0 of 8 bytes by task 17380 on cpu 1:
 ext4_writepages+0x13c/0x1d70 fs/ext4/inode.c:2666
 do_writepages+0x26b/0x3c0 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:400 [inline]
 __filemap_fdatawrite_range mm/filemap.c:433 [inline]
 __filemap_fdatawrite mm/filemap.c:439 [inline]
 filemap_flush+0x154/0x180 mm/filemap.c:466
 ext4_alloc_da_blocks+0x47/0xd0 fs/ext4/inode.c:3106
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:141
 __fput+0x295/0x520 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300
 do_syscall_64+0x50/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000503 -> 0x0000000000000504

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17380 Comm: syz-executor.1 Tainted: G        W         5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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