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(p200300cbc739d2008745c5208bf6b587.dip0.t-ipconnect.de. [2003:cb:c739:d200:8745:c520:8bf6:b587]) by smtp.gmail.com with ESMTPSA id q4-20020adff784000000b0030aec5e020fsm1241014wrp.86.2023.06.20.00.01.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Jun 2023 00:01:24 -0700 (PDT) Message-ID: <24f4a22e-7d3b-544b-320f-bba5abb92285@redhat.com> Date: Tue, 20 Jun 2023 09:01:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 To: Peter Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Matthew Wilcox , Andrea Arcangeli , John Hubbard , Mike Rapoport , Vlastimil Babka , "Kirill A . Shutemov" , Andrew Morton , Mike Kravetz , James Houghton , Hugh Dickins References: <20230613215346.1022773-1-peterx@redhat.com> <20230613215346.1022773-4-peterx@redhat.com> Content-Language: en-US From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH 3/7] mm/hugetlb: Add page_mask for hugetlb_follow_page_mask() In-Reply-To: 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 19.06.23 23:43, Peter Xu wrote: > On Tue, Jun 13, 2023 at 05:53:42PM -0400, Peter Xu wrote: >> @@ -6506,6 +6507,7 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, >> * because we hold the ptl lock and have verified pte_present(). >> */ >> WARN_ON_ONCE(try_grab_page(page, flags)); >> + *page_mask = huge_page_mask(h); > > Sorry, I was wrong this line. It should be: > > *page_mask = ~huge_page_mask(h) >> PAGE_SHIFT; > That's ... surprising. It feels like either page_mask or huge_page_mask() has a misleading name .... h->mask = ~(huge_page_size(h) - 1); For PMDs, we do ctx->page_mask = HPAGE_PMD_NR - 1; Maybe *page_mask = PHYS_PFN(huge_page_size(h)) - 1; Would be clearer. I guess "page_mask" should actually be "pfn_mask" ... but the meaning regarding PAGE_MASK are still inverted ... -- Cheers, David / dhildenb