syzbot

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BUG: KCSAN: data-race in copy_mm / mas_wmb_replace

read-write to 0xffff8881042dd804 of 4 bytes by task 20202 on cpu 0:
 mt_set_height lib/maple_tree.c:218 [inline]
 mas_put_in_tree lib/maple_tree.c:1556 [inline]
 mas_topiary_replace lib/maple_tree.c:2341 [inline]
 mas_wmb_replace+0x1bd/0x1610 lib/maple_tree.c:2433
 mas_split lib/maple_tree.c:3052 [inline]
 mas_commit_b_node lib/maple_tree.c:3072 [inline]
 mas_wr_bnode lib/maple_tree.c:3739 [inline]
 mas_wr_store_entry+0x16b6/0x2e70 lib/maple_tree.c:3771
 mas_store_prealloc+0x72e/0xa60 lib/maple_tree.c:5169
 vma_iter_store_overwrite mm/vma.h:544 [inline]
 vma_iter_store_new mm/vma.h:551 [inline]
 vma_complete+0x3f7/0x820 mm/vma.c:353
 __split_vma+0x5e3/0x660 mm/vma.c:566
 split_vma mm/vma.c:596 [inline]
 vma_modify+0xbcb/0xd30 mm/vma.c:1674
 vma_modify_flags+0x182/0x210 mm/vma.c:1694
 mprotect_fixup+0x30e/0x5e0 mm/mprotect.c:756
 do_mprotect_pkey+0x67b/0x920 mm/mprotect.c:930
 __do_sys_mprotect mm/mprotect.c:951 [inline]
 __se_sys_mprotect mm/mprotect.c:948 [inline]
 __x64_sys_mprotect+0x48/0x60 mm/mprotect.c:948
 x64_sys_call+0x2c3b/0x3000 arch/x86/include/generated/asm/syscalls_64.h:11
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881042dd7c0 of 1664 bytes by task 20203 on cpu 1:
 dup_mm kernel/fork.c:1523 [inline]
 copy_mm+0xe1/0x370 kernel/fork.c:1581
 copy_process+0xcbd/0x1f10 kernel/fork.c:2221
 kernel_clone+0x16b/0x5b0 kernel/fork.c:2651
 __do_sys_clone kernel/fork.c:2792 [inline]
 __se_sys_clone kernel/fork.c:2776 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2776
 x64_sys_call+0x12d0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 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: 20203 Comm: syz.1.3388 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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