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[91.12.97.88]) by smtp.gmail.com with ESMTPSA id l5sm317821wmh.0.2021.04.29.08.02.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Apr 2021 08:02:31 -0700 (PDT) Subject: Re: [PATCH v2 4/5] mm/huge_memory.c: remove unnecessary tlb_remove_page_size() for huge zero pmd To: Miaohe Lin , akpm@linux-foundation.org Cc: ziy@nvidia.com, william.kucharski@oracle.com, willy@infradead.org, yang.shi@linux.alibaba.com, aneesh.kumar@linux.ibm.com, rcampbell@nvidia.com, songliubraving@fb.com, kirill.shutemov@linux.intel.com, riel@surriel.com, hannes@cmpxchg.org, minchan@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Aaron Lu References: <20210429132648.305447-1-linmiaohe@huawei.com> <20210429132648.305447-5-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat Message-ID: Date: Thu, 29 Apr 2021 17:02:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210429132648.305447-5-linmiaohe@huawei.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D39F090009F8 X-Stat-Signature: k6kpybdc7cxkekrqod3dfhkwmw8r9iy1 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf19; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=170.10.133.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619708532-134181 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 29.04.21 15:26, Miaohe Lin wrote: > Commit aa88b68c3b1d ("thp: keep huge zero page pinned until tlb flush") > introduced tlb_remove_page() for huge zero page to keep it pinned until > flush is complete and prevents the page from being split under us. But > huge zero page is kept pinned until all relevant mm_users reach zero since > the commit 6fcb52a56ff6 ("thp: reduce usage of huge zero page's atomic > counter"). So tlb_remove_page_size() for huge zero pmd is unnecessary now. > > Signed-off-by: Miaohe Lin > --- > mm/huge_memory.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index e24a96de2e37..af30338ac49c 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1680,12 +1680,9 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > if (arch_needs_pgtable_deposit()) > zap_deposited_table(tlb->mm, pmd); > spin_unlock(ptl); > - if (is_huge_zero_pmd(orig_pmd)) > - tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); > } else if (is_huge_zero_pmd(orig_pmd)) { > zap_deposited_table(tlb->mm, pmd); > spin_unlock(ptl); > - tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); > } else { > struct page *page = NULL; > int flush_needed = 1; > This sounds sane to me Acked-by: David Hildenbrand -- Thanks, David / dhildenb