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BUG: KCSAN: data-race in task_mem / unmap_region

write to 0xffff88810b57c678 of 8 bytes by task 22969 on cpu 0:
 update_hiwater_rss include/linux/mm.h:1949 [inline]
 unmap_region+0x11d/0x1e0 mm/mmap.c:2675
 __do_munmap+0xea4/0x1340 mm/mmap.c:2908
 __vm_munmap mm/mmap.c:2931 [inline]
 __do_sys_munmap+0xa0/0x180 mm/mmap.c:2957
 __se_sys_munmap mm/mmap.c:2953 [inline]
 __x64_sys_munmap+0x2d/0x40 mm/mmap.c:2953
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810b57c678 of 8 bytes by task 4885 on cpu 1:
 task_mem+0xfb/0x3d0 fs/proc/task_mmu.c:50
 proc_pid_status+0x80f/0x13e0 fs/proc/array.c:446
 proc_single_show+0x84/0x100 fs/proc/base.c:775
 seq_read_iter+0x2d8/0x8e0 fs/seq_file.c:227
 seq_read+0x221/0x260 fs/seq_file.c:159
 vfs_read+0x154/0x5c0 fs/read_write.c:494
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4885 Comm: systemd-journal Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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