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Date:   Fri, 9 Dec 2022 14:36:52 -0800
From:   Mike Kravetz <mike.kravetz@oracle.com>
To:     James Houghton <jthoughton@google.com>
Cc:     Muchun Song <songmuchun@bytedance.com>,
        Peter Xu <peterx@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Mina Almasry <almasrymina@google.com>,
        Zach O'Keefe <zokeefe@google.com>,
        Manish Mishra <manish.mishra@nutanix.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Yang Shi <shy828301@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 05/47] hugetlb: make hugetlb_vma_lock_alloc return
 its failure reason
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References: <20221021163703.3218176-1-jthoughton@google.com>
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On 10/21/22 16:36, James Houghton wrote:
> Currently hugetlb_vma_lock_alloc doesn't return anything, as there is no
> need: if it fails, PMD sharing won't be enabled. However, HGM requires
> that the VMA lock exists, so we need to verify that
> hugetlb_vma_lock_alloc actually succeeded. If hugetlb_vma_lock_alloc
> fails, then we can pass that up to the caller that is attempting to
> enable HGM.

No serious objections to this change ...

However, there are currently only two places today where hugetlb_vma_lock_alloc
is called: hugetlb_reserve_pages and hugetlb_vm_op_open.  hugetlb_reserve_pages
is not an issue.  Since hugetlb_vm_op_open (as a defined vm_operation) returns
void, I am not sure how you plan to pass up an allocation failure.
Suspect this will become evident in subsequent patches.
-- 
Mike Kravetz