syzbot

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BUG: KCSAN: data-race in page_cache_ra_order / read_pages

read-write to 0xffff88812ce3bc80 of 4 bytes by task 25514 on cpu 0:
 read_pages+0x249/0x560 mm/readahead.c:170
 page_cache_ra_unbounded+0x223/0x2e0
 do_page_cache_ra mm/readahead.c:299 [inline]
 page_cache_ra_order mm/readahead.c:559 [inline]
 ondemand_readahead+0x550/0x6c0 mm/readahead.c:681
 page_cache_sync_ra+0x284/0x2a0 mm/readahead.c:708
 page_cache_sync_readahead include/linux/pagemap.h:1213 [inline]
 filemap_get_pages+0x254/0xea0 mm/filemap.c:2563
 filemap_read+0x1fb/0x670 mm/filemap.c:2658
 generic_file_read_iter+0x78/0x340 mm/filemap.c:2837
 ext4_file_read_iter+0x1d8/0x2a0
 call_read_iter include/linux/fs.h:1871 [inline]
 copy_splice_read+0x26b/0x4b0 fs/splice.c:367
 vfs_splice_read fs/splice.c:995 [inline]
 splice_direct_to_actor+0x2aa/0x690 fs/splice.c:1072
 do_splice_direct+0x10d/0x190 fs/splice.c:1197
 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

read to 0xffff88812ce3bc80 of 4 bytes by task 25517 on cpu 1:
 page_cache_ra_order+0x4a/0xf0 mm/readahead.c:559
 do_sync_mmap_readahead+0x36a/0x3b0 mm/filemap.c:3205
 filemap_fault+0x3d6/0xb70 mm/filemap.c:3297
 __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:3213 [inline]
 vm_mmap_pgoff+0x1a3/0x240 mm/util.c:548
 ksys_mmap_pgoff+0x2b8/0x330 mm/mmap.c:1409
 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 -> 0x0000001f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25517 Comm: syz-executor.3 Not tainted 6.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
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