From: Oliver Upton <oliver.upton@xxxxxxxxx>
commit f6a27d6dc51b288106adaf053cff9c9b9cc12c4e upstream.
The reference count on page table allocations is increased for every
'counted' PTE (valid or donated) in the table in addition to the initial
reference from ->zalloc_page(). kvm_pgtable_stage2_free_removed() fails
to drop the last reference on the root of the table walk, meaning we
leak memory.
Fix it by dropping the last reference after the free walker returns,
at which point all references for 'counted' PTEs have been released.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 5c359cca1faf ("KVM: arm64: Tear down unlinked stage-2 subtree after break-before-make")
Reported-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Tested-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230530193213.1663411-1-oliver.upton@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kvm/hyp/pgtable.c | 3 +++
1 file changed, 3 insertions(+)
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1333,4 +1333,7 @@ void kvm_pgtable_stage2_free_removed(str
};
WARN_ON(__kvm_pgtable_walk(&data, mm_ops, ptep, level + 1));
+
+ WARN_ON(mm_ops->page_count(pgtable) != 1);
+ mm_ops->put_page(pgtable);
}
