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BUG: KCSAN: data-race in filemap_fault / filemap_fault

write to 0xffff88810aac2498 of 8 bytes by task 8468 on cpu 0:
 do_sync_mmap_readahead mm/filemap.c:2631 [inline]
 filemap_fault+0x66a/0x12e0 mm/filemap.c:2723
 ext4_filemap_fault+0x4b/0x60 fs/ext4/inode.c:6191
 __do_fault mm/memory.c:3612 [inline]
 do_read_fault+0x403/0x760 mm/memory.c:4006
 do_fault mm/memory.c:4134 [inline]
 handle_pte_fault mm/memory.c:4374 [inline]
 __handle_mm_fault mm/memory.c:4509 [inline]
 handle_mm_fault+0xfeb/0x1770 mm/memory.c:4607
 do_user_addr_fault+0x33e/0x730 arch/x86/mm/fault.c:1372
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1485
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583

write to 0xffff88810aac2498 of 8 bytes by task 8461 on cpu 1:
 do_sync_mmap_readahead mm/filemap.c:2631 [inline]
 filemap_fault+0x66a/0x12e0 mm/filemap.c:2723
 ext4_filemap_fault+0x4b/0x60 fs/ext4/inode.c:6191
 __do_fault mm/memory.c:3612 [inline]
 do_read_fault+0x403/0x760 mm/memory.c:4006
 do_fault mm/memory.c:4134 [inline]
 handle_pte_fault mm/memory.c:4374 [inline]
 __handle_mm_fault mm/memory.c:4509 [inline]
 handle_mm_fault+0xfeb/0x1770 mm/memory.c:4607
 do_user_addr_fault+0x33e/0x730 arch/x86/mm/fault.c:1372
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1485
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8461 Comm: syz-fuzzer Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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