[moderation/CI] Re: Fix an imbalanced file ref count in the mmap syscall

[syzbot ci]

syzbot ci has tested the following series

[v1] Fix an imbalanced file ref count in the mmap syscall
https://lore.kernel.org/all/20260718123417....@gmail.com
* [PATCH] mm/vma: fix imbalanced file reference count, properly abort mmap_prepare

and found the following issue:
WARNING in tear_down_vmas

Full report is available here:
https://ci.syzbot.org/series/63d42f9f-f249-4678-8916-5464a15accd6

***

WARNING in tear_down_vmas

tree: mm-new
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/mm.git
base: 3827fe994db98623a5a619a72f15f57bf8274deb
arch: amd64
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config: https://ci.syzbot.org/builds/f57e989a-6273-4413-b35d-20dab5a41e92/config
syz repro: https://ci.syzbot.org/findings/8f36751f-0976-460a-b5ab-de97c9074c0a/syz_repro

------------[ cut here ]------------
!vma_is_attached(vma)
WARNING: ./include/linux/mmap_lock.h:435 at vma_assert_attached include/linux/mmap_lock.h:435 [inline], CPU#0: syz.2.19/5813
WARNING: ./include/linux/mmap_lock.h:435 at vma_mark_detached include/linux/mmap_lock.h:455 [inline], CPU#0: syz.2.19/5813
WARNING: ./include/linux/mmap_lock.h:435 at tear_down_vmas+0x381/0x520 mm/mmap.c:1261, CPU#0: syz.2.19/5813
Modules linked in:
CPU: 0 UID: 0 PID: 5813 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:vma_assert_attached include/linux/mmap_lock.h:435 [inline]
RIP: 0010:vma_mark_detached include/linux/mmap_lock.h:455 [inline]
RIP: 0010:tear_down_vmas+0x381/0x520 mm/mmap.c:1261
Code: 48 89 df e8 01 46 16 00 48 8b 44 24 18 48 39 03 0f 87 e0 00 00 00 e8 ce a8 a8 ff ff 44 24 04 e9 9a fd ff ff e8 c0 a8 a8 ff 90 <0f> 0b 90 e9 2c ff ff ff e8 b2 a8 a8 ff 90 0f 0b 90 e9 94 fe ff ff
RSP: 0018:ffffc90003cdf7e0 EFLAGS: 00010293
RAX: ffffffff821dbb90 RBX: ffff888115e14b40 RCX: ffff888171f9bb80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003cdf920 R08: ffff888115e14b43 R09: 1ffff11022bc2968
R10: dffffc0000000000 R11: ffffed1022bc2969 R12: ffff888115e14a80
R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
FS: 00007f15b88e36c0(0000) GS:ffff88818dc1c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9033eab095 CR3: 0000000173ace000 CR4: 00000000000006f0
Call Trace:
<TASK>
exit_mmap+0x4ca/0x9f0 mm/mmap.c:1320
__mmput+0x118/0x420 kernel/fork.c:1187
exit_mm+0x221/0x2d0 kernel/exit.c:610
do_exit+0x6cd/0x2360 kernel/exit.c:992
do_group_exit+0x22d/0x2f0 kernel/exit.c:1147
get_signal+0x121b/0x12c0 kernel/signal.c:3038
arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f15b799ce59
Code: Unable to access opcode bytes at 0x7f15b799ce2f.
RSP: 002b:00007f15b88e30e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f15b7c15fa8 RCX: 00007f15b799ce59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f15b7c15fa8
RBP: 00007f15b7c15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f15b7c16038 R14: 00007ffe1b61d9f0 R15: 00007ffe1b61dad8
</TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syz...@syzkaller.appspotmail.com

---
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[Pimyn Girgis]

#syz upstream

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--
Ⲡⲟⲓⲙⲏⲛ Ⲅⲉⲱⲣⲅⲓⲟⲥ - Pimyn Girgis
Software Engineer
Kernel Dynamic Analysis
pi...@google.com