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BUG: KCSAN: data-race in copyin / copyin

write to 0xffff888103c8b000 of 4096 bytes by task 20917 on cpu 0:
 instrument_copy_from_user include/linux/instrumented.h:106 [inline]
 copyin+0xab/0xc0 lib/iov_iter.c:151
 copy_page_from_iter_iovec lib/iov_iter.c:296 [inline]
 copy_page_from_iter+0x23f/0x5f0 lib/iov_iter.c:942
 process_vm_rw_pages mm/process_vm_access.c:46 [inline]
 process_vm_rw_single_vec mm/process_vm_access.c:120 [inline]
 process_vm_rw_core.isra.0+0x448/0x820 mm/process_vm_access.c:218
 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286
 __do_sys_process_vm_writev mm/process_vm_access.c:308 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:303 [inline]
 __x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:303
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888103c8b000 of 4096 bytes by task 20918 on cpu 1:
 instrument_copy_from_user include/linux/instrumented.h:106 [inline]
 copyin+0xab/0xc0 lib/iov_iter.c:151
 copy_page_from_iter_iovec lib/iov_iter.c:296 [inline]
 copy_page_from_iter+0x23f/0x5f0 lib/iov_iter.c:942
 process_vm_rw_pages mm/process_vm_access.c:46 [inline]
 process_vm_rw_single_vec mm/process_vm_access.c:120 [inline]
 process_vm_rw_core.isra.0+0x448/0x820 mm/process_vm_access.c:218
 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286
 __do_sys_process_vm_writev mm/process_vm_access.c:308 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:303 [inline]
 __x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:303
 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: 20918 Comm: syz-executor.0 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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