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BUG: KCSAN: data-race in do_sync_mmap_readahead / ondemand_readahead

write to 0xffff888104d7d398 of 8 bytes by task 1808 on cpu 1:
 do_sync_mmap_readahead+0x2cf/0x370 mm/filemap.c:2992
 filemap_fault+0x267/0xa10 mm/filemap.c:3089
 __do_fault mm/memory.c:3849 [inline]
 do_read_fault mm/memory.c:4164 [inline]
 do_fault mm/memory.c:4293 [inline]
 handle_pte_fault mm/memory.c:4551 [inline]
 __handle_mm_fault mm/memory.c:4686 [inline]
 handle_mm_fault+0xba6/0x1590 mm/memory.c:4784
 do_user_addr_fault+0x609/0xbe0 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1485 [inline]
 exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1541
 asm_exc_page_fault+0x1e/0x30

read to 0xffff888104d7d398 of 8 bytes by task 1797 on cpu 0:
 ondemand_readahead+0x110/0x700 mm/readahead.c:464
 page_cache_async_ra+0xed/0x120 mm/readahead.c:608
 page_cache_async_readahead include/linux/pagemap.h:1052 [inline]
 do_async_mmap_readahead+0x211/0x250 mm/filemap.c:3023
 filemap_fault+0x101/0xa10 mm/filemap.c:3079
 __do_fault mm/memory.c:3849 [inline]
 do_read_fault mm/memory.c:4164 [inline]
 do_fault mm/memory.c:4293 [inline]
 handle_pte_fault mm/memory.c:4551 [inline]
 __handle_mm_fault mm/memory.c:4686 [inline]
 handle_mm_fault+0xba6/0x1590 mm/memory.c:4784
 do_user_addr_fault+0x609/0xbe0 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1485 [inline]
 exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1541
 asm_exc_page_fault+0x1e/0x30

value changed: 0x000000000000039e -> 0x000000000000036e

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1797 Comm: syz-fuzzer Tainted: G        W         5.16.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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