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BUG: KCSAN: data-race in ondemand_readahead / ondemand_readahead

write to 0xffff88816a0c6480 of 4 bytes by task 7923 on cpu 1:
 ondemand_readahead+0x358/0x690
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:717
 do_async_mmap_readahead mm/filemap.c:3169 [inline]
 filemap_fault+0x3da/0xc30 mm/filemap.c:3223
 __do_fault mm/memory.c:4266 [inline]
 do_shared_fault mm/memory.c:4693 [inline]
 do_fault mm/memory.c:4767 [inline]
 do_pte_missing mm/memory.c:3731 [inline]
 handle_pte_fault mm/memory.c:5039 [inline]
 __handle_mm_fault mm/memory.c:5180 [inline]
 handle_mm_fault+0x17db/0x2dd0 mm/memory.c:5345
 do_user_addr_fault arch/x86/mm/fault.c:1413 [inline]
 handle_page_fault arch/x86/mm/fault.c:1505 [inline]
 exc_page_fault+0x2f7/0x6c0 arch/x86/mm/fault.c:1561
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
 rep_movs_alternative+0x4a/0x70 arch/x86/lib/copy_user_64.S:65
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline]
 copy_to_user_iter lib/iov_iter.c:25 [inline]
 iterate_iovec include/linux/iov_iter.h:51 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:247 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 _copy_to_iter+0x2bf/0xb20 lib/iov_iter.c:186
 copy_page_to_iter+0x171/0x2b0 lib/iov_iter.c:381
 copy_folio_to_iter include/linux/uio.h:181 [inline]
 filemap_read+0x424/0x680 mm/filemap.c:2644
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2772
 ext4_file_read_iter+0x1d8/0x2a0
 do_iter_read+0x4af/0x780 fs/read_write.c:795
 vfs_readv fs/read_write.c:915 [inline]
 do_preadv+0x159/0x230 fs/read_write.c:1007
 __do_sys_preadv fs/read_write.c:1057 [inline]
 __se_sys_preadv fs/read_write.c:1052 [inline]
 __x64_sys_preadv+0x58/0x60 fs/read_write.c:1052
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88816a0c6480 of 4 bytes by task 7924 on cpu 0:
 ondemand_readahead+0x14d/0x690 mm/readahead.c:580
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:717
 do_async_mmap_readahead mm/filemap.c:3169 [inline]
 filemap_fault+0x3da/0xc30 mm/filemap.c:3223
 __do_fault mm/memory.c:4266 [inline]
 do_shared_fault mm/memory.c:4693 [inline]
 do_fault mm/memory.c:4767 [inline]
 do_pte_missing mm/memory.c:3731 [inline]
 handle_pte_fault mm/memory.c:5039 [inline]
 __handle_mm_fault mm/memory.c:5180 [inline]
 handle_mm_fault+0x17db/0x2dd0 mm/memory.c:5345
 do_user_addr_fault arch/x86/mm/fault.c:1413 [inline]
 handle_page_fault arch/x86/mm/fault.c:1505 [inline]
 exc_page_fault+0x2f7/0x6c0 arch/x86/mm/fault.c:1561
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
 rep_movs_alternative+0x4a/0x70 arch/x86/lib/copy_user_64.S:65
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline]
 copy_to_user_iter lib/iov_iter.c:25 [inline]
 iterate_iovec include/linux/iov_iter.h:51 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:247 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 _copy_to_iter+0x2bf/0xb20 lib/iov_iter.c:186
 copy_page_to_iter+0x171/0x2b0 lib/iov_iter.c:381
 copy_folio_to_iter include/linux/uio.h:181 [inline]
 filemap_read+0x424/0x680 mm/filemap.c:2644
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2772
 ext4_file_read_iter+0x1d8/0x2a0
 do_iter_read+0x4af/0x780 fs/read_write.c:795
 vfs_readv fs/read_write.c:915 [inline]
 do_preadv+0x159/0x230 fs/read_write.c:1007
 __do_sys_preadv fs/read_write.c:1057 [inline]
 __se_sys_preadv fs/read_write.c:1052 [inline]
 __x64_sys_preadv+0x58/0x60 fs/read_write.c:1052
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000040 -> 0x00000020

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7924 Comm: syz-executor.1 Tainted: G        W          6.7.0-rc5-syzkaller-00014-g26aff849438c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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