syzbot

==================================================================
BUG: KCSAN: data-race in copy_mm / mmap_write_unlock

read-write to 0xffff8881035f52c8 of 4 bytes by task 6571 on cpu 0:
 do_raw_write_seqcount_end include/linux/seqlock.h:453 [inline]
 mm_lock_seqcount_end include/linux/mmap_lock.h:131 [inline]
 vma_end_write_all include/linux/mmap_lock.h:572 [inline]
 mmap_write_unlock+0x70/0xc0 include/linux/mmap_lock.h:578
 do_mbind mm/mempolicy.c:1611 [inline]
 kernel_mbind mm/mempolicy.c:1757 [inline]
 __do_sys_mbind mm/mempolicy.c:1831 [inline]
 __se_sys_mbind+0xc54/0xdd0 mm/mempolicy.c:1827
 __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1827
 x64_sys_call+0x2b72/0x3020 arch/x86/include/generated/asm/syscalls_64.h:238
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881035f5100 of 1664 bytes by task 6574 on cpu 1:
 dup_mm kernel/fork.c:1528 [inline]
 copy_mm+0xe1/0x370 kernel/fork.c:1586
 copy_process+0x1087/0x2370 kernel/fork.c:2264
 kernel_clone+0x1a5/0x5e0 kernel/fork.c:2721
 __do_sys_clone kernel/fork.c:2862 [inline]
 __se_sys_clone kernel/fork.c:2846 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2846
 x64_sys_call+0x1222/0x3020 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6574 Comm: syz.3.854 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================