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Thu, 23 Sep 2021 19:24:10 -0700 (PDT) Received: from [10.255.74.217] ([139.177.225.249]) by smtp.gmail.com with ESMTPSA id q2sm10249656pjo.27.2021.09.23.19.24.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Sep 2021 19:24:10 -0700 (PDT) Subject: Re: [PATCH] mm/memory_failure: Fix the missing pte_unmap() call To: Andrew Morton Cc: naoya.horiguchi@nec.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, songmuchun@bytedance.com References: <20210923122642.4999-1-zhengqi.arch@bytedance.com> <20210923161738.990b61933c96df78bc1bf96d@linux-foundation.org> From: Qi Zheng Message-ID: <2eca94ce-4e26-aff6-240d-39baf1a9cc36@bytedance.com> Date: Fri, 24 Sep 2021 10:24:06 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210923161738.990b61933c96df78bc1bf96d@linux-foundation.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D52CAD000096 X-Stat-Signature: gypzo5mw3543krqgaeit3eg7t3tgictq Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=OeuIzFZd; spf=pass (imf15.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.210.173 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-HE-Tag: 1632450251-940857 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 9/24/21 7:17 AM, Andrew Morton wrote: > On Thu, 23 Sep 2021 20:26:42 +0800 Qi Zheng wrote: > >> The paired pte_unmap() call is missing before the >> dev_pagemap_mapping_shift() returns. So fix it. >> >> ... >> >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -306,6 +306,7 @@ static unsigned long dev_pagemap_mapping_shift(struct page *page, >> struct vm_area_struct *vma) >> { >> unsigned long address = vma_address(page, vma); >> + unsigned long ret = 0; >> pgd_t *pgd; >> p4d_t *p4d; >> pud_t *pud; >> @@ -330,10 +331,12 @@ static unsigned long dev_pagemap_mapping_shift(struct page *page, >> return PMD_SHIFT; >> pte = pte_offset_map(pmd, address); >> if (!pte_present(*pte)) >> - return 0; >> + goto unmap; >> if (pte_devmap(*pte)) >> - return PAGE_SHIFT; >> - return 0; >> + ret = PAGE_SHIFT; >> +unmap: >> + pte_unmap(pte); >> + return ret; >> } >> > > This is neater? Yes, and I see this neater version has merged into your mm tree, thanks. :) > > +++ a/mm/memory-failure.c > @@ -330,11 +330,8 @@ static unsigned long dev_pagemap_mapping > if (pmd_devmap(*pmd)) > return PMD_SHIFT; > pte = pte_offset_map(pmd, address); > - if (!pte_present(*pte)) > - goto unmap; > - if (pte_devmap(*pte)) > + if (pte_present(*pte) && pte_devmap(*pte)) > ret = PAGE_SHIFT; > -unmap: > pte_unmap(pte); > return ret; > } > _ >