This is a note to let you know that I've just added the patch titled
KVM: x86/mmu: Update number of zapped pages even if page list is stable
to the 5.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-mmu-update-number-of-zapped-pages-even-if-page-list-is-stable.patch
and it can be found in the queue-5.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b28cb0cd2c5e80a8c0feb408a0e4b0dbb6d132c5 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Wed, 11 May 2022 14:51:22 +0000
Subject: KVM: x86/mmu: Update number of zapped pages even if page list is stable
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit b28cb0cd2c5e80a8c0feb408a0e4b0dbb6d132c5 upstream.
When zapping obsolete pages, update the running count of zapped pages
regardless of whether or not the list has become unstable due to zapping
a shadow page with its own child shadow pages. If the VM is backed by
mostly 4kb pages, KVM can zap an absurd number of SPTEs without bumping
the batch count and thus without yielding. In the worst case scenario,
this can cause a soft lokcup.
watchdog: BUG: soft lockup - CPU#12 stuck for 22s! [dirty_log_perf_:13020]
RIP: 0010:workingset_activation+0x19/0x130
mark_page_accessed+0x266/0x2e0
kvm_set_pfn_accessed+0x31/0x40
mmu_spte_clear_track_bits+0x136/0x1c0
drop_spte+0x1a/0xc0
mmu_page_zap_pte+0xef/0x120
__kvm_mmu_prepare_zap_page+0x205/0x5e0
kvm_mmu_zap_all_fast+0xd7/0x190
kvm_mmu_invalidate_zap_pages_in_memslot+0xe/0x10
kvm_page_track_flush_slot+0x5c/0x80
kvm_arch_flush_shadow_memslot+0xe/0x10
kvm_set_memslot+0x1a8/0x5d0
__kvm_set_memory_region+0x337/0x590
kvm_vm_ioctl+0xb08/0x1040
Fixes: fbb158cb88b6 ("KVM: x86/mmu: Revert "Revert "KVM: MMU: zap pages in batch""")
Reported-by: David Matlack <dmatlack@xxxxxxxxxx>
Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20220511145122.3133334-1-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5611,6 +5611,7 @@ static void kvm_zap_obsolete_pages(struc
{
struct kvm_mmu_page *sp, *node;
int nr_zapped, batch = 0;
+ bool unstable;
restart:
list_for_each_entry_safe_reverse(sp, node,
@@ -5642,11 +5643,12 @@ restart:
goto restart;
}
- if (__kvm_mmu_prepare_zap_page(kvm, sp,
- &kvm->arch.zapped_obsolete_pages, &nr_zapped)) {
- batch += nr_zapped;
+ unstable = __kvm_mmu_prepare_zap_page(kvm, sp,
+ &kvm->arch.zapped_obsolete_pages, &nr_zapped);
+ batch += nr_zapped;
+
+ if (unstable)
goto restart;
- }
}
/*
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-5.17/kvm-free-new-dirty-bitmap-if-creating-a-new-memslot-fails.patch
queue-5.17/kvm-x86-mmu-update-number-of-zapped-pages-even-if-page-list-is-stable.patch
