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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pc043-00CjO6-HV; Tue, 14 Mar 2023 08:31:23 +0000 Date: Tue, 14 Mar 2023 08:31:23 +0000 From: Matthew Wilcox To: Peng Zhang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com, vishal.moola@gmail.com, sidhartha.kumar@oracle.com, wangkefeng.wang@huawei.com, sunnanyong@huawei.com Subject: Re: [PATCH 2/3] userfaultfd: convert __mcopy_atomic_hugetlb() to use a folio Message-ID: References: <20230314033734.481904-1-zhangpeng362@huawei.com> <20230314033734.481904-3-zhangpeng362@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230314033734.481904-3-zhangpeng362@huawei.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 31A93140016 X-Stat-Signature: s9u49b18t7n8kp467yrb8b5eyi6afrje X-HE-Tag: 1678782690-282257 X-HE-Meta: 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 6D/NQ130 r59h+ei/UpCMlZ3qPYpwgVAgJy6hp9VBPiF7kXQFhUvwzesMMPur8MXAa3CsH/TzdsJz9hENjmP8IlikRt5QfyOljCzCcJlStIq6eXkuPetZeHB0wAkJ1WPuEmql7Co81YYWVz78t+NpA5TJGG/iq1PQG0+f0e3vBUYuk8wfES7/Cd262KsgF+Cql0XCKV/wGwVTWw3+zBNc4Qz1kMsv52shDZLk3/E370Zn2NOvi7MhXdhwmkrBDt18R98WGyHwJt+/wFg5AifZKk9f36GfyChaT+Q== 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 Tue, Mar 14, 2023 at 03:37:33AM +0000, Peng Zhang wrote: > +++ b/include/linux/mm.h > @@ -3546,9 +3546,8 @@ extern void copy_user_huge_page(struct page *dst, struct page *src, > unsigned long addr_hint, > struct vm_area_struct *vma, > unsigned int pages_per_huge_page); > -extern long copy_huge_page_from_user(struct page *dst_page, > +extern long copy_large_folio_from_user(struct folio *dst_folio, You can drop the 'extern'. > +++ b/mm/memory.c > @@ -5769,26 +5769,28 @@ void copy_user_huge_page(struct page *dst, struct page *src, > process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg); > } > > -long copy_huge_page_from_user(struct page *dst_page, > +long copy_large_folio_from_user(struct folio *dst_folio, > const void __user *usr_src, > - unsigned int pages_per_huge_page, > bool allow_pagefault) > { > void *page_kaddr; > unsigned long i, rc = 0; > - unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; > + unsigned int nr_pages = folio_nr_pages(dst_folio); > + unsigned long ret_val = nr_pages * PAGE_SIZE; > struct page *subpage; > + struct folio *inner_folio; What is an 'inner folio'? > - for (i = 0; i < pages_per_huge_page; i++) { > - subpage = nth_page(dst_page, i); > + for (i = 0; i < nr_pages; i++) { > + subpage = folio_page(dst_folio, i); > + inner_folio = page_folio(subpage); > if (allow_pagefault) > - page_kaddr = kmap(subpage); > + page_kaddr = kmap_local_folio(inner_folio, 0); This doesn't do what you think it does. Did you test this? > else > page_kaddr = kmap_atomic(subpage); Pretty sure all this should be converted to kmap_local and the atomic bits should go away. > rc = copy_from_user(page_kaddr, > usr_src + i * PAGE_SIZE, PAGE_SIZE); > if (allow_pagefault) > - kunmap(subpage); > + kunmap_local(page_kaddr); > else > kunmap_atomic(page_kaddr); > > @@ -5796,7 +5798,7 @@ long copy_huge_page_from_user(struct page *dst_page, > if (rc) > break; > > - flush_dcache_page(subpage); > + flush_dcache_folio(inner_folio); The flush should probably be pulled outside the loop. > + err = copy_large_folio_from_user(folio, > + (const void __user *) src_addr, true); I wonder if this shouldn't be 'copy_folio_from_user()'. after all, it'll work for any size folio, right?