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BUG: KCSAN: data-race in do_sync_mmap_readahead / ondemand_readahead

write to 0xffff888125156384 of 4 bytes by task 10869 on cpu 0:
 do_sync_mmap_readahead+0x34e/0x3b0 mm/filemap.c:3203
 filemap_fault+0x3d6/0xb70 mm/filemap.c:3297
 __do_fault mm/memory.c:4198 [inline]
 do_shared_fault mm/memory.c:4602 [inline]
 do_fault mm/memory.c:4674 [inline]
 do_pte_missing mm/memory.c:3664 [inline]
 handle_pte_fault mm/memory.c:4939 [inline]
 __handle_mm_fault mm/memory.c:5079 [inline]
 handle_mm_fault+0x131b/0x2c10 mm/memory.c:5233
 do_user_addr_fault arch/x86/mm/fault.c:1392 [inline]
 handle_page_fault arch/x86/mm/fault.c:1486 [inline]
 exc_page_fault+0x24d/0x650 arch/x86/mm/fault.c:1542
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

read to 0xffff888125156384 of 4 bytes by task 10871 on cpu 1:
 page_cache_ra_order mm/readahead.c:559 [inline]
 ondemand_readahead+0x4e3/0x6c0 mm/readahead.c:681
 page_cache_async_ra+0x9d/0xb0 mm/readahead.c:730
 do_async_mmap_readahead mm/filemap.c:3233 [inline]
 filemap_fault+0x38a/0xb70 mm/filemap.c:3287
 __do_fault mm/memory.c:4198 [inline]
 do_read_fault mm/memory.c:4547 [inline]
 do_fault mm/memory.c:4670 [inline]
 do_pte_missing mm/memory.c:3664 [inline]
 handle_pte_fault mm/memory.c:4939 [inline]
 __handle_mm_fault mm/memory.c:5079 [inline]
 handle_mm_fault+0x1224/0x2c10 mm/memory.c:5233
 faultin_page mm/gup.c:959 [inline]
 __get_user_pages+0x42e/0xd20 mm/gup.c:1258
 populate_vma_page_range mm/gup.c:1649 [inline]
 __mm_populate+0x23b/0x360 mm/gup.c:1758
 mm_populate include/linux/mm.h:3196 [inline]
 vm_mmap_pgoff+0x1a3/0x240 mm/util.c:548
 ksys_mmap_pgoff+0x2b8/0x330 mm/mmap.c:1408
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000020 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10871 Comm: syz-executor.2 Not tainted 6.5.0-rc1-syzkaller-00196-gbde7f150276b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
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