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BUG: KCSAN: data-race in do_sync_mmap_readahead / ondemand_readahead

read to 0xffff888104aa7898 of 8 bytes by task 19335 on cpu 1:
 ondemand_readahead+0x16b/0x6c0 mm/readahead.c:594
 page_cache_sync_ra+0x284/0x2a0 mm/readahead.c:709
 page_cache_sync_readahead include/linux/pagemap.h:1211 [inline]
 filemap_get_pages+0x257/0xea0 mm/filemap.c:2595
 filemap_read+0x223/0x680 mm/filemap.c:2690
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2837
 ext4_file_read_iter+0x1cc/0x290
 call_read_iter include/linux/fs.h:1862 [inline]
 generic_file_splice_read+0xe3/0x290 fs/splice.c:419
 do_splice_to fs/splice.c:902 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:973
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 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

write to 0xffff888104aa7898 of 8 bytes by task 19340 on cpu 0:
 do_sync_mmap_readahead+0x320/0x3b0 mm/filemap.c:3183
 filemap_fault+0x3d6/0xb70 mm/filemap.c:3279
 __do_fault mm/memory.c:4176 [inline]
 do_read_fault mm/memory.c:4530 [inline]
 do_fault mm/memory.c:4659 [inline]
 do_pte_missing mm/memory.c:3647 [inline]
 handle_pte_fault mm/memory.c:4947 [inline]
 __handle_mm_fault mm/memory.c:5089 [inline]
 handle_mm_fault+0x12f4/0x2c60 mm/memory.c:5243
 faultin_page mm/gup.c:925 [inline]
 __get_user_pages+0x363/0xc30 mm/gup.c:1147
 populate_vma_page_range mm/gup.c:1543 [inline]
 __mm_populate+0x23d/0x370 mm/gup.c:1652
 mm_populate include/linux/mm.h:3153 [inline]
 vm_mmap_pgoff+0x1a3/0x240 mm/util.c:548
 ksys_mmap_pgoff+0x2ac/0x320 mm/mmap.c:1440
 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: 0x00000000000003cb -> 0x00000000000003cd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19340 Comm: syz-executor.2 Not tainted 6.4.0-rc5-syzkaller-00178-g33f2b5785a2b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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