syzbot

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BUG: KCSAN: data-race in munlock_vma_pages_range / try_to_unmap_one

write to 0xffff8880a7257b40 of 8 bytes by task 25800 on cpu 0:
 munlock_vma_pages_range+0x57/0x6b0 mm/mlock.c:448
 munlock_vma_pages_all mm/internal.h:306 [inline]
 exit_mmap+0x243/0x2f0 mm/mmap.c:3114
 __mmput kernel/fork.c:1088 [inline]
 mmput+0xe2/0x260 kernel/fork.c:1109
 exit_mm kernel/exit.c:485 [inline]
 do_exit+0x640/0x1880 kernel/exit.c:788
 do_group_exit+0xae/0x1a0 kernel/exit.c:899
 __do_sys_exit_group kernel/exit.c:910 [inline]
 __se_sys_exit_group kernel/exit.c:908 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:908
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a7257b40 of 8 bytes by task 25838 on cpu 1:
 try_to_unmap_one+0x33a/0x1740 mm/rmap.c:1432
 rmap_walk_file+0x240/0x590 mm/rmap.c:1920
 rmap_walk+0x10e/0x180 mm/rmap.c:1938
 try_to_munlock+0x8e/0xb0 mm/rmap.c:1789
 __munlock_isolated_page+0x85/0x190 mm/mlock.c:138
 __munlock_pagevec+0x316/0x690 mm/mlock.c:346
 munlock_vma_pages_range+0x52a/0x6b0 mm/mlock.c:499
 munlock_vma_pages_all mm/internal.h:306 [inline]
 exit_mmap+0x243/0x2f0 mm/mmap.c:3114
 __mmput kernel/fork.c:1088 [inline]
 mmput+0xe2/0x260 kernel/fork.c:1109
 exit_mm kernel/exit.c:485 [inline]
 do_exit+0x640/0x1880 kernel/exit.c:788
 do_group_exit+0xae/0x1a0 kernel/exit.c:899
 get_signal+0x2a7/0x1290 kernel/signal.c:2734
 do_signal+0x2b/0x670 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25838 Comm: syz-executor.3 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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