Re: [syzbot] [mm?] KCSAN: data-race in mas_wr_store_entry / mtree_range_walk (2)

[syzbot <syzbot+38a879f4a73497f2dfef@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    551c722f4080 Merge tag 'rtc-7.3-fixes' of git://git.kernel..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1426a3f5580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ea1e6d8de13bab08
dashboard link: https://syzkaller.appspot.com/bug?extid=38a879f4a73497f2dfef
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179a2b15580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+38a879f4a73497f2dfef@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mas_wr_store_entry / mtree_range_walk

write to 0xffff8881105bc000 of 8 bytes by task 3634 on cpu 1:
 mte_set_node_dead lib/maple_tree.c:305 [inline]
 mas_put_in_tree lib/maple_tree.c:1652 [inline]
 mas_replace_node lib/maple_tree.c:1667 [inline]
 mas_wr_node_store lib/maple_tree.c:3276 [inline]
 mas_wr_store_entry+0x3c1f/0x5ac0 lib/maple_tree.c:3606
 mas_store_prealloc+0x421/0x670 lib/maple_tree.c:5031
 vma_iter_store_overwrite mm/vma.h:704 [inline]
 commit_merge+0x7b4/0x840 mm/vma.c:847
 vma_merge_existing_range mm/vma.c:1070 [inline]
 vma_modify+0x9eb/0xd50 mm/vma.c:1756
 vma_modify_flags+0x1be/0x250 mm/vma.c:1799
 mprotect_fixup+0x382/0x660 mm/mprotect.c:824
 do_mprotect_pkey+0x69f/0x950 mm/mprotect.c:1002
 __do_sys_mprotect mm/mprotect.c:1023 [inline]
 __se_sys_mprotect mm/mprotect.c:1020 [inline]
 __x64_sys_mprotect+0x48/0x60 mm/mprotect.c:1020
 x64_sys_call+0xd54/0x2550 arch/x86/include/generated/asm/syscalls_64.h:11
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881105bc000 of 8 bytes by task 3640 on cpu 0:
 ma_dead_node lib/maple_tree.c:505 [inline]
 mtree_range_walk+0x35a/0x480 lib/maple_tree.c:2119
 mas_state_walk lib/maple_tree.c:3013 [inline]
 mas_walk+0x1ac/0x340 lib/maple_tree.c:4458
 lock_vma_under_rcu+0xc9/0x210 mm/mmap_lock.c:304
 do_user_addr_fault+0x239/0x1060 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1483 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1536
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

value changed: 0xffff8881058c0526 -> 0xffff8881105bc000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3640 Comm: syz-executor108 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================


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