KCSAN: data-race in mmap_region / task

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in mmap_region / task_vsize mm				1	1882d	1882d	0/28	auto-closed as invalid on 2020/02/12 15:36

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BUG: KCSAN: data-race in mmap_region / task_vsize

write to 0xffff8881451a5300 of 8 bytes by task 2282 on cpu 1:
 vm_stat_account mm/mmap.c:3335 [inline]
 mmap_region+0x6f6/0x1260 mm/mmap.c:1849
 do_mmap+0x781/0xc20 mm/mmap.c:1575
 vm_mmap_pgoff+0x117/0x1f0 mm/util.c:519
 ksys_mmap_pgoff+0xcf/0x350 mm/mmap.c:1624
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881451a5300 of 8 bytes by task 2287 on cpu 0:
 task_vsize+0x15/0x30 fs/proc/task_mmu.c:84
 do_task_stat+0x13e/0x1260 fs/proc/array.c:477
 proc_tgid_stat+0x2f/0x40 fs/proc/array.c:655
 proc_single_show+0x84/0x100 fs/proc/base.c:775
 seq_read_iter+0x2e1/0x930 fs/seq_file.c:230
 seq_read+0x248/0x290 fs/seq_file.c:162
 do_loop_readv_writev fs/read_write.c:750 [inline]
 do_iter_read+0x370/0x5d0 fs/read_write.c:792
 vfs_readv fs/read_write.c:910 [inline]
 do_preadv+0x159/0x240 fs/read_write.c:1002
 __do_sys_preadv fs/read_write.c:1052 [inline]
 __se_sys_preadv fs/read_write.c:1047 [inline]
 __x64_sys_preadv+0x54/0x60 fs/read_write.c:1047
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000005311 -> 0x0000000000005332

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2287 Comm: syz-executor.4 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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