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BUG: KCSAN: data-race in ext4_setattr / mpage_process_page_bufs

write to 0xffff888105fc7618 of 8 bytes by task 5745 on cpu 1:
 i_size_write include/linux/fs.h:916 [inline]
 ext4_setattr+0xd7f/0xef0 fs/ext4/inode.c:5498
 notify_change+0x8a3/0xac0 fs/attr.c:398
 do_truncate+0xf7/0x140 fs/open.c:64
 handle_truncate fs/namei.c:3082 [inline]
 do_open fs/namei.c:3430 [inline]
 path_openat+0x1925/0x1ec0 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_open fs/open.c:1224 [inline]
 __se_sys_open fs/open.c:1220 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1220
 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 0xffff888105fc7618 of 8 bytes by task 5743 on cpu 0:
 i_size_read include/linux/fs.h:894 [inline]
 mpage_process_page_bufs+0x34/0x560 fs/ext4/inode.c:2198
 mpage_prepare_extent_to_map+0x4f6/0x650 fs/ext4/inode.c:2632
 ext4_writepages+0x706/0x1d70 fs/ext4/inode.c:2760
 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]
 file_write_and_wait_range+0x1ae/0x240 mm/filemap.c:810
 ext4_sync_file+0x105/0x670 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2955 [inline]
 ext4_buffered_write_iter+0x3af/0x400 fs/ext4/file.c:277
 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

value changed: 0x0000000000fff000 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5743 Comm: syz-executor.1 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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