syzbot

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BUG: KCSAN: data-race in shmem_fallocate / shmem_fault

write to 0xffff8881774102f0 of 8 bytes by task 14770 on cpu 1:
 shmem_fallocate+0x244/0x880 mm/shmem.c:2753
 vfs_fallocate+0x355/0x3d0 fs/open.c:323
 madvise_remove+0x11a/0x1d0 mm/madvise.c:991
 madvise_vma_behavior mm/madvise.c:1015 [inline]
 madvise_walk_vmas mm/madvise.c:1250 [inline]
 do_madvise+0x6b7/0x1ac0 mm/madvise.c:1429
 __do_sys_madvise mm/madvise.c:1442 [inline]
 __se_sys_madvise mm/madvise.c:1440 [inline]
 __x64_sys_madvise+0x5d/0x70 mm/madvise.c:1440
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881774102f0 of 8 bytes by task 14761 on cpu 0:
 shmem_fault+0x8f/0x3d0 mm/shmem.c:2086
 __do_fault mm/memory.c:4203 [inline]
 do_shared_fault mm/memory.c:4609 [inline]
 do_fault+0x5c7/0xaf0 mm/memory.c:4687
 handle_pte_fault mm/memory.c:4955 [inline]
 __handle_mm_fault mm/memory.c:5097 [inline]
 handle_mm_fault+0x877/0xa80 mm/memory.c:5218
 do_user_addr_fault+0x4a1/0x980 arch/x86/mm/fault.c:1428
 handle_page_fault arch/x86/mm/fault.c:1519 [inline]
 exc_page_fault+0x60/0x160 arch/x86/mm/fault.c:1575
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570
 copy_user_short_string+0xd/0x40 arch/x86/lib/copy_user_64.S:232
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
 _copy_to_user+0x72/0x90 lib/usercopy.c:34
 copy_to_user include/linux/uaccess.h:169 [inline]
 put_timespec64+0x51/0x90 kernel/time/time.c:812
 nanosleep_copyout+0x47/0xc0 kernel/time/hrtimer.c:2026
 do_cpu_nanosleep+0x2b7/0x310 kernel/time/posix-cpu-timers.c:1533
 posix_cpu_nsleep_restart+0x52/0x70 kernel/time/posix-cpu-timers.c:1575
 __do_sys_restart_syscall+0x2d/0x40 kernel/signal.c:3001
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0xffffc90000c1fca8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14761 Comm: syz-executor.1 Not tainted 6.1.0-rc7-syzkaller-00123-ga4412fdd49dc-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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