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(p200300cbc70c6c0092a406f8ff7e6853.dip0.t-ipconnect.de. [2003:cb:c70c:6c00:92a4:6f8:ff7e:6853]) by smtp.gmail.com with ESMTPSA id x3-20020a1c7c03000000b003fefaf299b6sm88234wmc.38.2023.09.06.10.17.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 06 Sep 2023 10:17:03 -0700 (PDT) Message-ID: <6dfbc043-c969-f78d-1e56-5434026246ea@redhat.com> Date: Wed, 6 Sep 2023 19:17:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v2 3/5] mm/memory_hotplug: use nth_page() in place of direct struct page manipulation. Content-Language: en-US To: Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org Cc: Andrew Morton , Thomas Bogendoerfer , "Matthew Wilcox (Oracle)" , Mike Kravetz , Muchun Song , "Mike Rapoport (IBM)" , stable@vger.kernel.org, Muchun Song References: <20230906150309.114360-1-zi.yan@sent.com> <20230906150309.114360-4-zi.yan@sent.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230906150309.114360-4-zi.yan@sent.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06.09.23 17:03, Zi Yan wrote: > From: Zi Yan Subject talks about "nth_page()" but that's not what this patch does. > > When dealing with hugetlb pages, manipulating struct page pointers > directly can get to wrong struct page, since struct page is not guaranteed > to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle > it properly. ^ dito > > Fixes: eeb0efd071d8 ("mm,memory_hotplug: fix scan_movable_pages() for gigantic hugepages") > Cc: > Signed-off-by: Zi Yan > Reviewed-by: Muchun Song > --- > mm/memory_hotplug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 1b03f4ec6fd2..3b301c4023ff 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1689,7 +1689,7 @@ static int scan_movable_pages(unsigned long start, unsigned long end, > */ > if (HPageMigratable(head)) > goto found; > - skip = compound_nr(head) - (page - head); > + skip = compound_nr(head) - (pfn - page_to_pfn(head)); > pfn += skip - 1; > } > return -ENOENT; I suspect systems without VMEMMAP also don't usually support gigantic pages AND hotunplug :) With the subject+description fixed Acked-by: David Hildenbrand -- Cheers, David / dhildenb