From: Dan Carpenter <dan.carpenter@oracle.com>
To: bgardon@google.com
Cc: kvm@vger.kernel.org
Subject: [bug report] KVM: x86/mmu: Use an rwlock for the x86 MMU
Date: Mon, 26 Jul 2021 10:52:38 +0300 [thread overview]
Message-ID: <20210726075238.GA10030@kili> (raw)
[ This is not the correct patch to blame, but there is something going
on here which I don't understand so this email is more about me
learning rather than reporting bugs. - dan ]
Hello Ben Gardon,
The patch 531810caa9f4: "KVM: x86/mmu: Use an rwlock for the x86 MMU"
from Feb 2, 2021, leads to the following static checker warning:
arch/x86/kvm/mmu/mmu.c:5769 kvm_mmu_zap_all()
warn: sleeping in atomic context
arch/x86/kvm/mmu/mmu.c
5756 void kvm_mmu_zap_all(struct kvm *kvm)
5757 {
5758 struct kvm_mmu_page *sp, *node;
5759 LIST_HEAD(invalid_list);
5760 int ign;
5761
5762 write_lock(&kvm->mmu_lock);
^^^^^^^^^^^^^^^^^^^^^^^^^^
This line bumps the preempt count.
5763 restart:
5764 list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) {
5765 if (WARN_ON(sp->role.invalid))
5766 continue;
5767 if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign))
5768 goto restart;
--> 5769 if (cond_resched_rwlock_write(&kvm->mmu_lock))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This line triggers a sleeping in atomic warning. What's going on here
that I'm not understanding?
5770 goto restart;
5771 }
5772
5773 kvm_mmu_commit_zap_page(kvm, &invalid_list);
5774
5775 if (is_tdp_mmu_enabled(kvm))
5776 kvm_tdp_mmu_zap_all(kvm);
5777
5778 write_unlock(&kvm->mmu_lock);
5779 }
regards,
dan carpenter
next reply other threads:[~2021-07-26 7:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 7:52 Dan Carpenter [this message]
2021-07-26 16:47 ` [bug report] KVM: x86/mmu: Use an rwlock for the x86 MMU Ben Gardon
2021-07-27 0:16 ` Sean Christopherson
2021-07-27 8:06 ` Dan Carpenter
2021-07-26 16:53 ` David Matlack
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