Re: [PATCH v5 1/6] mm/gup: remove unused vmas parameter from get_user_pages()

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On 16.05.23 16:30, Sean Christopherson wrote:
On Tue, May 16, 2023, David Hildenbrand wrote:
On 15.05.23 21:07, Sean Christopherson wrote:
On Sun, May 14, 2023, Lorenzo Stoakes wrote:
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index cb5c13eee193..eaa5bb8dbadc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2477,7 +2477,7 @@ static inline int check_user_page_hwpoison(unsigned long addr)
   {
   	int rc, flags = FOLL_HWPOISON | FOLL_WRITE;
-	rc = get_user_pages(addr, 1, flags, NULL, NULL);
+	rc = get_user_pages(addr, 1, flags, NULL);
   	return rc == -EHWPOISON;

Unrelated to this patch, I think there's a pre-existing bug here.  If gup() returns
a valid page, KVM will leak the refcount and unintentionally pin the page.  That's

When passing NULL as "pages" to get_user_pages(), __get_user_pages_locked()
won't set FOLL_GET. As FOLL_PIN is also not set, we won't be messing with
the mapcount of the page.

For completeness: s/mapcount/refcount/ :)


Ah, that's what I'm missing.



--
Thanks,

David / dhildenb




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