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BUG: KCSAN: data-race in ondemand_readahead / read_pages

read to 0xffff88813c2bea84 of 4 bytes by task 30455 on cpu 1:
 ondemand_readahead+0x195/0x6c0 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+0x254/0xea0 mm/filemap.c:2601
 filemap_read+0x1fb/0x670 mm/filemap.c:2696
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2842
 ext4_file_read_iter+0x1d8/0x2a0
 call_read_iter include/linux/fs.h:1866 [inline]
 copy_splice_read+0x26b/0x4b0 fs/splice.c:366
 vfs_splice_read fs/splice.c:888 [inline]
 splice_direct_to_actor+0x2bd/0x660 fs/splice.c:961
 do_splice_direct+0x104/0x180 fs/splice.c:1070
 do_sendfile+0x3b6/0x9a0 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 0xffff88813c2bea84 of 4 bytes by task 30458 on cpu 0:
 read_pages+0x291/0x560 mm/readahead.c:173
 page_cache_ra_unbounded+0x223/0x2e0
 do_page_cache_ra mm/readahead.c:300 [inline]
 page_cache_ra_order+0xd5/0xf0 mm/readahead.c:560
 do_sync_mmap_readahead+0x364/0x3b0 mm/filemap.c:3210
 filemap_fault+0x3d3/0xb70 mm/filemap.c:3302
 __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:969 [inline]
 __get_user_pages+0x363/0xc30 mm/gup.c:1191
 populate_vma_page_range mm/gup.c:1587 [inline]
 __mm_populate+0x23d/0x370 mm/gup.c:1696
 mm_populate include/linux/mm.h:3176 [inline]
 vm_mmap_pgoff+0x1a3/0x240 mm/util.c:548
 ksys_mmap_pgoff+0x2b8/0x330 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: 0x00000005 -> 0x00000007

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30458 Comm: syz-executor.4 Not tainted 6.4.0-syzkaller-01371-g04fc8904d5d1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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