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BUG: KCSAN: data-race in ondemand_readahead / read_pages

write to 0xffff888104988ca4 of 4 bytes by task 15283 on cpu 0:
 ondemand_readahead+0x346/0x6c0 mm/readahead.c:661
 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:2601
 filemap_read+0x223/0x680 mm/filemap.c:2696
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2843
 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

read to 0xffff888104988ca4 of 4 bytes by task 15297 on cpu 1:
 read_pages+0x266/0x560 mm/readahead.c:172
 page_cache_ra_unbounded+0x2a9/0x2e0 mm/readahead.c:270
 do_page_cache_ra mm/readahead.c:300 [inline]
 page_cache_ra_order mm/readahead.c:560 [inline]
 ondemand_readahead+0x550/0x6c0 mm/readahead.c:682
 page_cache_async_ra+0x9d/0xb0 mm/readahead.c:731
 do_async_mmap_readahead mm/filemap.c:3221 [inline]
 filemap_fault+0x38a/0xb70 mm/filemap.c:3275
 __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: 0x00000000 -> 0x00000009

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15297 Comm: syz-executor.3 Not tainted 6.4.0-rc6-syzkaller-00242-g1639fae5132b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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