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[70.30.145.63]) by smtp.gmail.com with ESMTPSA id r8-20020a05620a298800b006bb29d932e1sm11330704qkp.105.2023.01.12.10.02.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Jan 2023 10:02:18 -0800 (PST) Date: Thu, 12 Jan 2023 13:02:17 -0500 From: Peter Xu To: James Houghton Cc: Mike Kravetz , Muchun Song , David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , Zach O'Keefe , Manish Mishra , Naoya Horiguchi , "Dr . David Alan Gilbert" , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Baolin Wang , Miaohe Lin , Yang Shi , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 19/46] hugetlb: add HGM support for follow_hugetlb_page Message-ID: References: <20230105101844.1893104-1-jthoughton@google.com> <20230105101844.1893104-20-jthoughton@google.com> MIME-Version: 1.0 In-Reply-To: <20230105101844.1893104-20-jthoughton@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 24BE7A0015 X-Stat-Signature: fscex93gqy7tnay9gt4n9ohqnmhf1q9x X-Rspam-User: X-HE-Tag: 1673546553-614704 X-HE-Meta: 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 K9Jr+DH0 NuIprW7CorkggXpMs3PiYwnmgU+HjqAjIE7SO09qtsy0lZV5Whiro/wLEhJv5sd/nyrsMj8uqblRPryRl9uwDDUwXgnhX2IpjfbmmdZh9oy5dOJPVww3TUyeKw4gwzeKfrnksTEzNrsjodBHZEC5x3WMcbA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 05, 2023 at 10:18:17AM +0000, James Houghton wrote: > @@ -6731,22 +6746,22 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, > * and skip the same_page loop below. > */ > if (!pages && !vmas && !pfn_offset && > - (vaddr + huge_page_size(h) < vma->vm_end) && > - (remainder >= pages_per_huge_page(h))) { > - vaddr += huge_page_size(h); > - remainder -= pages_per_huge_page(h); > - i += pages_per_huge_page(h); > + (vaddr + pages_per_hpte < vma->vm_end) && > + (remainder >= pages_per_hpte)) { > + vaddr += pages_per_hpte; This silently breaks hugetlb GUP.. should be vaddr += hugetlb_pte_size(&hpte); It caused misterious MISSING events when I'm playing with this tree, and I'm surprised it rooted here. So far the most time consuming one. :) > + remainder -= pages_per_hpte; > + i += pages_per_hpte; > spin_unlock(ptl); > hugetlb_vma_unlock_read(vma); > continue; > } -- Peter Xu