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Mon, 3 Nov 2025 21:22:30 +0800 (CST) Received: from kwepemj100009.china.huawei.com (unknown [7.202.194.3]) by mail.maildlp.com (Postfix) with ESMTPS id 1D4CA180491; Mon, 3 Nov 2025 21:24:04 +0800 (CST) Received: from DESKTOP-A37P9LK.huawei.com (10.67.109.17) by kwepemj100009.china.huawei.com (7.202.194.3) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 3 Nov 2025 21:24:03 +0800 From: Xie Yuanbin To: , , , , , , , , , , , , , , , , , CC: , , , , , , , Xie Yuanbin Subject: Re: [PATCH 1/2] x86/mm: support memory-failure on 32-bits with SPARSEMEM Date: Mon, 3 Nov 2025 21:23:58 +0800 Message-ID: <20251103132358.79766-1-xieyuanbin1@huawei.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <5ace86cc-0b2d-4306-8bc1-dfc34cccef1a@redhat.com> References: <5ace86cc-0b2d-4306-8bc1-dfc34cccef1a@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.67.109.17] X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemj100009.china.huawei.com (7.202.194.3) X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1E2D44000E X-Stat-Signature: esikncxxphrhm1ewrgezj9fjtg3f5ezs X-HE-Tag: 1762176250-185255 X-HE-Meta: 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 1yfL6aX+ 0J/v95ZbzWdUHh0qFfz0eNXWhoerfiYRuRznmJnQP9rnSsskBYB6yztF+3S7mPfGfIKDtGDEsvk1xkxnt5vAUQNOZkQODE/8pPcTJ1rqwn3yDCz5gkkz8Nj+B/qx8fYEFaB2f3jmRpo0TAyUYkSzPFh0YfX7lHJaNTSu4vyEuiGsgFCRUK05joHHURrFPQOkp4OLV45Oq4m2qMKHnnqFtKYIlfA2gmQNFw4h4YPY15qboXEYCEI+vxBkhd7no1WMKo4Qo+01rRP89mvwHVCLdoATp46CfJ4dYONa7VYaiyTZY4XM/XkXfn3I3nAV1dcVqvEl+UQXqWmImuPGgK/7w21LH3Q== 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: List-Subscribe: List-Unsubscribe: On Mon, 3 Nov 2025 13:08:38 +0100, David Hildenbrand wrote: >> The historical commit d949f36f1865c60239d4 ("x86: Fix hwpoison code >> related build failure on 32-bit NUMAQ"), disabled x86_32's >> memory-failure when SPARSEMEM is enabled, because the number of >> page-flags are insufficient. >> >> The commit 09022bc196d23484a7a5 ("mm: remove PG_error") removes a >> page flag, so memory-failure can now be enable now. > > In the meantime, we added PG_dropbehind Okay, I completely understand now. For historical versions, MEMORY_FAILURE cannot be enabled with x86_32 && SPARSEMEM because the number of page-flags are insufficient. At least it has been so from 5.10.x to 6.9.x. The commit 46df8e73a4a3f1445f2a ("mm: free up PG_slab") from 6.10-rc1 remove a flag that allows MEMORY_FAILURE to be enabled from here on. The commit 09022bc196d23484a7a5 ("mm: remove PG_error") from 6.12-rc1 remove another flag. The commit cceba6f7e46c48deca43 ("mm: add PG_dropbehind folio flag") from 6.14-rc1 add a flag, but MEMORY_FAILURE can still be enabled. At least for the current version, memory-failure can be safely enabled. The number of pageflags reaches its maximum value under the following conditions: HIGHMEM && SPARSEMEM && X86_PAE && X86_PAT. In this case, if MEMORY_FAILURE is enabled, the number of pageflags just reached the limit of 32. I will update the V2 patch to describe it. > Cheers > > David / dhildenb Thanks! Xie Yuanbin