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BUG: KCSAN: data-race in ext4_setattr / mpage_process_page_bufs

write to 0xffff888104ac05d8 of 8 bytes by task 3380 on cpu 1:
 i_size_write include/linux/fs.h:913 [inline]
 ext4_setattr+0xd7e/0xf20 fs/ext4/inode.c:5440
 notify_change+0x8a3/0xac0 fs/attr.c:410
 do_truncate+0xf7/0x140 fs/open.c:64
 handle_truncate fs/namei.c:3082 [inline]
 do_open fs/namei.c:3430 [inline]
 path_openat+0x192c/0x1eb0 fs/namei.c:3559
 do_filp_open+0x105/0x220 fs/namei.c:3586
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1200
 do_sys_open fs/open.c:1216 [inline]
 __do_sys_creat fs/open.c:1292 [inline]
 __se_sys_creat fs/open.c:1286 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1286
 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 0xffff888104ac05d8 of 8 bytes by task 3382 on cpu 0:
 i_size_read include/linux/fs.h:891 [inline]
 mpage_process_page_bufs+0x34/0x560 fs/ext4/inode.c:2190
 mpage_prepare_extent_to_map+0x4f6/0x650 fs/ext4/inode.c:2624
 ext4_writepages+0xa78/0x1e80 fs/ext4/inode.c:2796
 do_writepages+0x1cb/0x320 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:399 [inline]
 __filemap_fdatawrite_range mm/filemap.c:432 [inline]
 filemap_write_and_wait_range+0x1b2/0x340 mm/filemap.c:703
 ext4_punch_hole+0x14c/0xa20 fs/ext4/inode.c:3962
 ext4_fallocate+0xea/0x540 fs/ext4/extents.c:4668
 vfs_fallocate+0x486/0x720 fs/open.c:307
 ksys_fallocate fs/open.c:330 [inline]
 __do_sys_fallocate fs/open.c:338 [inline]
 __se_sys_fallocate fs/open.c:336 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:336
 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

value changed: 0x000000000000fd14 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3382 Comm: syz-executor.2 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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