==================================================================
BUG: KCSAN: data-race in next_uptodate_page / simple_write_end

write to 0xffff88812e84c5c0 of 8 bytes by task 13044 on cpu 0:
 i_size_write include/linux/fs.h:911 [inline]
 simple_write_end+0x293/0x330 fs/libfs.c:591
 generic_perform_write+0x23a/0x3d0 mm/filemap.c:3784
 __generic_file_write_iter+0x174/0x310 mm/filemap.c:3900
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3932
 call_write_iter include/linux/fs.h:2158 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x77d/0x8c0 fs/read_write.c:594
 ksys_write+0xce/0x180 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812e84c5c0 of 8 bytes by task 13049 on cpu 1:
 i_size_read include/linux/fs.h:889 [inline]
 next_uptodate_page+0x323/0x670 mm/filemap.c:3259
 next_map_page mm/filemap.c:3284 [inline]
 filemap_map_pages+0x761/0x870 mm/filemap.c:3340
 do_fault_around mm/memory.c:4151 [inline]
 do_read_fault mm/memory.c:4166 [inline]
 do_fault mm/memory.c:4300 [inline]
 handle_pte_fault mm/memory.c:4558 [inline]
 __handle_mm_fault mm/memory.c:4693 [inline]
 handle_mm_fault+0xd83/0x1a50 mm/memory.c:4791
 faultin_page mm/gup.c:951 [inline]
 __get_user_pages+0x32b/0xbc0 mm/gup.c:1173
 populate_vma_page_range mm/gup.c:1506 [inline]
 __mm_populate+0x24d/0x380 mm/gup.c:1615
 mm_populate include/linux/mm.h:2623 [inline]
 vm_mmap_pgoff+0x142/0x1d0 mm/util.c:524
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1629
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000c7f000 -> 0x0000000000c81000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13049 Comm: syz-executor.3 Tainted: G        W         5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================