syzbot

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BUG: KCSAN: data-race in ondemand_readahead / ondemand_readahead

write to 0xffff88812ba6a384 of 4 bytes by task 14664 on cpu 0:
 ondemand_readahead+0x308/0x670 mm/readahead.c:645
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:715
 do_async_mmap_readahead mm/filemap.c:3181 [inline]
 filemap_fault+0x3da/0xc30 mm/filemap.c:3235
 __do_fault+0xb2/0x1f0 mm/memory.c:4396
 do_shared_fault mm/memory.c:4818 [inline]
 do_fault mm/memory.c:4892 [inline]
 do_pte_missing mm/memory.c:3745 [inline]
 handle_pte_fault mm/memory.c:5164 [inline]
 __handle_mm_fault mm/memory.c:5305 [inline]
 handle_mm_fault+0xb9a/0x27c0 mm/memory.c:5470
 do_user_addr_fault arch/x86/mm/fault.c:1355 [inline]
 handle_page_fault arch/x86/mm/fault.c:1498 [inline]
 exc_page_fault+0x401/0x6d0 arch/x86/mm/fault.c:1554
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

write to 0xffff88812ba6a384 of 4 bytes by task 14676 on cpu 1:
 ondemand_readahead+0x350/0x670
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:715
 do_async_mmap_readahead mm/filemap.c:3181 [inline]
 filemap_fault+0x3da/0xc30 mm/filemap.c:3235
 __do_fault+0xb2/0x1f0 mm/memory.c:4396
 do_read_fault mm/memory.c:4758 [inline]
 do_fault mm/memory.c:4888 [inline]
 do_pte_missing mm/memory.c:3745 [inline]
 handle_pte_fault mm/memory.c:5164 [inline]
 __handle_mm_fault mm/memory.c:5305 [inline]
 handle_mm_fault+0xd5f/0x27c0 mm/memory.c:5470
 do_user_addr_fault arch/x86/mm/fault.c:1406 [inline]
 handle_page_fault arch/x86/mm/fault.c:1498 [inline]
 exc_page_fault+0x2f9/0x6d0 arch/x86/mm/fault.c:1554
 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:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000020 -> 0x00000010

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14676 Comm: syz-executor.2 Not tainted 6.8.0-rc7-syzkaller-00051-g67be068d31d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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