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BUG: KCSAN: data-race in __get_user_pages / __get_user_pages

read to 0xffff8880b42bd690 of 8 bytes by task 13241 on cpu 0:
 faultin_page mm/gup.c:653 [inline]
 __get_user_pages+0x769/0x1130 mm/gup.c:851
 populate_vma_page_range+0xe6/0x100 mm/gup.c:1235
 __mm_populate+0x168/0x2a0 mm/gup.c:1283
 mm_populate include/linux/mm.h:2347 [inline]
 vm_mmap_pgoff+0x181/0x190 mm/util.c:511
 ksys_mmap_pgoff+0x99/0x420 mm/mmap.c:1607
 __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/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880b42bd690 of 8 bytes by task 13244 on cpu 1:
 faultin_page mm/gup.c:653 [inline]
 __get_user_pages+0x78b/0x1130 mm/gup.c:851
 __get_user_pages_locked mm/gup.c:1029 [inline]
 get_user_pages_remote+0x206/0x3e0 mm/gup.c:1175
 process_vm_rw_single_vec mm/process_vm_access.c:109 [inline]
 process_vm_rw_core.isra.0+0x3a4/0x910 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/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13244 Comm: syz-executor.0 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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