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BUG: KCSAN: data-race in ext4_setattr / next_uptodate_page

write to 0xffff8881062f6840 of 8 bytes by task 2944 on cpu 0:
 i_size_write include/linux/fs.h:871 [inline]
 ext4_setattr+0xd54/0xec0 fs/ext4/inode.c:5481
 notify_change+0x8a3/0xa80 fs/attr.c:398
 do_truncate fs/open.c:64 [inline]
 vfs_truncate+0x2ff/0x470 fs/open.c:112
 do_sys_truncate fs/open.c:135 [inline]
 __do_sys_truncate fs/open.c:147 [inline]
 __se_sys_truncate fs/open.c:145 [inline]
 __x64_sys_truncate+0xa0/0x120 fs/open.c:145
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881062f6840 of 8 bytes by task 2943 on cpu 1:
 i_size_read include/linux/fs.h:849 [inline]
 next_uptodate_page+0x323/0x670 mm/filemap.c:3146
 next_map_page mm/filemap.c:3171 [inline]
 filemap_map_pages+0x761/0x870 mm/filemap.c:3227
 do_fault_around mm/memory.c:3961 [inline]
 do_read_fault mm/memory.c:3975 [inline]
 do_fault mm/memory.c:4108 [inline]
 handle_pte_fault mm/memory.c:4367 [inline]
 __handle_mm_fault mm/memory.c:4502 [inline]
 handle_mm_fault+0xda3/0x1a70 mm/memory.c:4600
 faultin_page mm/gup.c:908 [inline]
 __get_user_pages+0x947/0xee0 mm/gup.c:1127
 populate_vma_page_range mm/gup.c:1460 [inline]
 __mm_populate+0x24d/0x380 mm/gup.c:1508
 mm_populate include/linux/mm.h:2621 [inline]
 vm_mmap_pgoff+0x145/0x1d0 mm/util.c:524
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1638
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2943 Comm: syz-executor.1 Tainted: G        W         5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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