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BUG: KCSAN: data-race in copy_page_from_iter / copy_page_from_iter

write to 0xffff88802bfcb000 of 4096 bytes by task 9195 on cpu 1:
 instrument_copy_from_user include/linux/instrumented.h:106 [inline]
 copyin lib/iov_iter.c:152 [inline]
 copy_page_from_iter_iovec lib/iov_iter.c:297 [inline]
 copy_page_from_iter+0x31f/0x5a0 lib/iov_iter.c:943
 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+0x478/0x760 mm/process_vm_access.c:218
 process_vm_rw+0x14e/0x1d0 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+0x76/0x90 mm/process_vm_access.c:303
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88802bfcb000 of 4096 bytes by task 9185 on cpu 0:
 instrument_copy_from_user include/linux/instrumented.h:106 [inline]
 copyin lib/iov_iter.c:152 [inline]
 copy_page_from_iter_iovec lib/iov_iter.c:297 [inline]
 copy_page_from_iter+0x31f/0x5a0 lib/iov_iter.c:943
 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+0x478/0x760 mm/process_vm_access.c:218
 process_vm_rw+0x14e/0x1d0 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+0x76/0x90 mm/process_vm_access.c:303
 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: 0 PID: 9185 Comm: syz-executor.4 Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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