Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 21 Dec 2021 10:58:42 -0800 | Subject | Re: [PATCH v1 06/11] mm: support GUP-triggered unsharing via FAULT_FLAG_UNSHARE (!hugetlb) |
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On Tue, Dec 21, 2021 at 10:51 AM David Hildenbrand <david@redhat.com> wrote: > > For that purpose the pincount would already kind-off work. Not precise, > but at least something ("this page cannot possibly have been pinned").
That part actually exists already, ie put_page_refs() has this:
#ifdef CONFIG_DEBUG_VM if (VM_WARN_ON_ONCE_PAGE(page_ref_count(page) < refs, page)) return; #endif
And yeah, it shouldn't have that '#ifdef CONFIG_DEBUG_VM' there, but I think it's because the non-CONFIG_DEBUG_VM #define for VM_WARN_ON_ONCE_PAGE() is broken, and doesn't return 0.
Linus
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