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BUG: KCSAN: data-race in __get_user_pages / __get_user_pages

write to 0xffff8880ac4446d0 of 8 bytes by task 21447 on cpu 1:
 faultin_page mm/gup.c:653 [inline]
 __get_user_pages+0x7b1/0x1160 mm/gup.c:845
 __get_user_pages_locked mm/gup.c:1023 [inline]
 get_user_pages_remote+0x206/0x3e0 mm/gup.c:1163
 process_vm_rw_single_vec mm/process_vm_access.c:109 [inline]
 process_vm_rw_core.isra.0+0x3a4/0x8c0 mm/process_vm_access.c:216
 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:284
 __do_sys_process_vm_writev mm/process_vm_access.c:306 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:301 [inline]
 __x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:301
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880ac4446d0 of 8 bytes by task 21487 on cpu 0:
 faultin_page mm/gup.c:653 [inline]
 __get_user_pages+0x78f/0x1160 mm/gup.c:845
 populate_vma_page_range+0xe6/0x100 mm/gup.c:1223
 __mm_populate+0x168/0x2a0 mm/gup.c:1271
 mm_populate include/linux/mm.h:2357 [inline]
 vm_mmap_pgoff+0x181/0x190 mm/util.c:501
 ksys_mmap_pgoff+0x99/0x420 mm/mmap.c:1629
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21487 Comm: syz-executor.5 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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