Re: [syzbot] [kvm?] BUG: sleeping function called from invalid context in kvm_mmu_notifier_invalidate_range_start

[syzbot <syzbot+c3178b6b512446632bac@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    9b87fdc9af2f Merge tag 'sched_ext-for-7.3-rc3-fixes' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16f46bf9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b454dc6b1b7acd30
dashboard link: https://syzkaller.appspot.com/bug?extid=c3178b6b512446632bac
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12f23925580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16f23925580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d9d20c79bd3c/disk-9b87fdc9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2a6a8f176798/vmlinux-9b87fdc9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/db8864d1c812/bzImage-9b87fdc9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c3178b6b512446632bac@syzkaller.appspotmail.com

BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
in_atomic(): 0, irqs_disabled(): 0, non_block: 1, pid: 38, name: oom_reaper
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
locks held by oom_reaper/38: 4, last CPU#1:
 #0: ffff8880370147b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:619 [inline]
 #0: ffff8880370147b0 (&mm->mmap_lock){++++}-{4:4}, at: oom_reap_task_mm mm/oom_kill.c:566 [inline]
 #0: ffff8880370147b0 (&mm->mmap_lock){++++}-{4:4}, at: oom_reap_task mm/oom_kill.c:609 [inline]
 #0: ffff8880370147b0 (&mm->mmap_lock){++++}-{4:4}, at: oom_reaper+0x2b4/0xc10 mm/oom_kill.c:650
 #1: ffffffff8e30af80 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}, at: mmu_notifier_invalidate_range_start_nonblock include/linux/mmu_notifier.h:495 [inline]
 #1: ffffffff8e30af80 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}, at: zap_vma_for_reaping+0x193/0x380 mm/memory.c:2266
 #2: ffffffff8e30afd8 (srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
 #2: ffffffff8e30afd8 (srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:305 [inline]
 #2: ffffffff8e30afd8 (srcu){.+.+}-{0:0}, at: mn_hlist_invalidate_range_start mm/mmu_notifier.c:515 [inline]
 #2: ffffffff8e30afd8 (srcu){.+.+}-{0:0}, at: __mmu_notifier_invalidate_range_start+0x5c6/0xb80 mm/mmu_notifier.c:580
 #3: ffff8880465ad560 (&kvm->mn_invalidate_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #3: ffff8880465ad560 (&kvm->mn_invalidate_lock){+.+.}-{3:3}, at: kvm_mmu_notifier_invalidate_range_start+0x1b6/0xc10 virt/kvm/kvm_main.c:745
CPU: 1 UID: 0 PID: 38 Comm: oom_reaper Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 __might_resched+0x31b/0x470 kernel/sched/core.c:9257
 __rt_spin_lock kernel/locking/spinlock_rt.c:48 [inline]
 rt_spin_lock+0xc2/0x400 kernel/locking/spinlock_rt.c:57
 spin_lock include/linux/spinlock_rt.h:45 [inline]
 kvm_mmu_notifier_invalidate_range_start+0x1b6/0xc10 virt/kvm/kvm_main.c:745
 mn_hlist_invalidate_range_start mm/mmu_notifier.c:525 [inline]
 __mmu_notifier_invalidate_range_start+0x709/0xb80 mm/mmu_notifier.c:580
 mmu_notifier_invalidate_range_start_nonblock include/linux/mmu_notifier.h:498 [inline]
 zap_vma_for_reaping+0x1f7/0x380 mm/memory.c:2266
 __oom_reap_task_mm mm/oom_kill.c:548 [inline]
 oom_reap_task_mm mm/oom_kill.c:585 [inline]
 oom_reap_task mm/oom_kill.c:609 [inline]
 oom_reaper+0x519/0xc10 mm/oom_kill.c:650
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
oom_reaper: reaped process 8617 (syz.2.1028), now anon-rss:0kB, file-rss:72kB, shmem-rss:0kB


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