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[121.45.173.48]) by smtp.gmail.com with ESMTPSA id 2sm6934784pfi.116.2021.03.07.00.19.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Mar 2021 00:19:01 -0800 (PST) Date: Sun, 7 Mar 2021 19:18:57 +1100 From: Balbir Singh To: Muchun Song Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com, david@redhat.com, naoya.horiguchi@nec.com, joao.m.martins@oracle.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v17 5/9] mm: hugetlb: set the PageHWPoison to the raw error page Message-ID: <20210307081857.GE1223287@balbir-desktop> References: <20210225132130.26451-1-songmuchun@bytedance.com> <20210225132130.26451-6-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210225132130.26451-6-songmuchun@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Feb 25, 2021 at 09:21:26PM +0800, Muchun Song wrote: > Because we reuse the first tail vmemmap page frame and remap it > with read-only, we cannot set the PageHWPosion on some tail pages. > So we can use the head[4].private (There are at least 128 struct > page structures associated with the optimized HugeTLB page, so > using head[4].private is safe) to record the real error page index > and set the raw error page PageHWPoison later. > Does the hardcoding of 4 come from HUGETLB_CGROUP_MIN_ORDER, if so do we need to hardcode 4? Also, I am not sure about the comment on safety and 128 struct pages Balbir