syzbot

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BUG: KCSAN: data-race in mas_wmb_replace / mtree_range_walk

write to 0xffff888103a3e900 of 8 bytes by task 31356 on cpu 0:
 mas_set_parent lib/maple_tree.c:495 [inline]
 mas_adopt_children lib/maple_tree.c:1549 [inline]
 mas_topiary_replace lib/maple_tree.c:1842 [inline]
 mas_wmb_replace+0x908/0x1760 lib/maple_tree.c:2083
 mas_wr_store_entry+0x54ff/0x5ad0 lib/maple_tree.c:-1
 mas_store_prealloc+0x43e/0x690 lib/maple_tree.c:4936
 vma_iter_store_overwrite mm/vma.h:616 [inline]
 vma_iter_store_new mm/vma.h:623 [inline]
 vma_complete+0x3c7/0x850 mm/vma.c:359
 __split_vma+0x5db/0x640 mm/vma.c:569
 split_vma mm/vma.c:599 [inline]
 vma_modify+0xbee/0xca0 mm/vma.c:1699
 vma_modify_flags+0x182/0x210 mm/vma.c:1719
 mprotect_fixup+0x3a2/0x680 mm/mprotect.c:789
 do_mprotect_pkey+0x6ae/0x960 mm/mprotect.c:967
 __do_sys_mprotect mm/mprotect.c:988 [inline]
 __se_sys_mprotect mm/mprotect.c:985 [inline]
 __x64_sys_mprotect+0x48/0x60 mm/mprotect.c:985
 x64_sys_call+0x2768/0x3020 arch/x86/include/generated/asm/syscalls_64.h:11
 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 0xffff888103a3e900 of 8 bytes by task 31357 on cpu 1:
 ma_dead_node lib/maple_tree.c:544 [inline]
 mtree_range_walk+0x350/0x490 lib/maple_tree.c:2051
 mas_state_walk lib/maple_tree.c:2952 [inline]
 mas_walk+0x1cc/0x370 lib/maple_tree.c:4366
 lock_vma_under_rcu+0xc9/0x210 mm/mmap_lock.c:304
 do_user_addr_fault+0x232/0x1050 arch/x86/mm/fault.c:1325
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

value changed: 0xffff88812f2aca16 -> 0xffff888119290e16

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 31357 Comm: syz.1.9413 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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