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BUG: KCSAN: data-race in ondemand_readahead / ondemand_readahead

read to 0xffff888147a23878 of 8 bytes by task 24049 on cpu 0:
 ondemand_readahead+0x13a/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:4265 [inline]
 do_read_fault mm/memory.c:4628 [inline]
 do_fault mm/memory.c:4762 [inline]
 do_pte_missing mm/memory.c:3730 [inline]
 handle_pte_fault mm/memory.c:5038 [inline]
 __handle_mm_fault mm/memory.c:5179 [inline]
 handle_mm_fault+0x13bd/0x2dd0 mm/memory.c:5344
 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+0x30/0x70 arch/x86/lib/copy_user_64.S:50
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:127 [inline]
 _copy_from_user+0x80/0xd0 lib/usercopy.c:23
 copy_from_user include/linux/uaccess.h:183 [inline]
 copy_msghdr_from_user+0x54/0x2a0 net/socket.c:2514
 recvmsg_copy_msghdr net/socket.c:2769 [inline]
 ___sys_recvmsg net/socket.c:2841 [inline]
 do_recvmmsg+0x290/0x720 net/socket.c:2939
 __sys_recvmmsg net/socket.c:3018 [inline]
 __do_sys_recvmmsg net/socket.c:3041 [inline]
 __se_sys_recvmmsg net/socket.c:3034 [inline]
 __x64_sys_recvmmsg+0xe2/0x160 net/socket.c:3034
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff888147a23878 of 8 bytes by task 24050 on cpu 1:
 ondemand_readahead+0x566/0x690 mm/readahead.c:606
 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:4265 [inline]
 do_read_fault mm/memory.c:4628 [inline]
 do_fault mm/memory.c:4762 [inline]
 do_pte_missing mm/memory.c:3730 [inline]
 handle_pte_fault mm/memory.c:5038 [inline]
 __handle_mm_fault mm/memory.c:5179 [inline]
 handle_mm_fault+0x13bd/0x2dd0 mm/memory.c:5344
 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
 fault_in_readable+0xf8/0x1b0
 fault_in_iov_iter_readable+0x152/0x190 lib/iov_iter.c:94
 generic_perform_write+0x106/0x410 mm/filemap.c:3908
 ext4_buffered_write_iter+0x1f6/0x370 fs/ext4/file.c:299
 ext4_file_write_iter+0x297/0xe10
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x48a/0x790 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000082 -> 0x0000000000000174

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24050 Comm: syz-executor.1 Tainted: G        W          6.7.0-rc2-syzkaller-00242-g090472ed9c92 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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