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([2a00:a040:199:85d9:d6b:b848:9578:6d4e]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e71b7270asm5274449f8f.11.2026.10.30.14.17.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 30 Oct 2026 14:17:11 -0700 (PDT) Message-ID: <1b2cd93a-37c0-4ca1-a8db-8ffaeec565da@columbia.edu> Date: Fri, 30 Oct 2026 23:17:09 +0200 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/memory-failure: fix folio refcount leak and min_order_for_split() locking To: "David Hildenbrand (Arm)" Cc: akpm@linux-foundation.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, linmiaohe@huawei.com, nao.horiguchi@gmail.com, richard.weiyang@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mcgrof@kernel.org, liyouhong@kylinos.cn References: <20260806-try_to_split_thp_page-v1-1-a259e3387e38@kernel.org> <20261030105022.903008-1-tz2294@columbia.edu> <40eadc1b-5057-4286-9be2-021cb16bc020@kernel.org> Content-Language: en-US From: Tal Zussman In-Reply-To: <40eadc1b-5057-4286-9be2-021cb16bc020@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: CUbKp7Zngz_GAd105swbDsFdc9dq93io X-Proofpoint-ORIG-GUID: CUbKp7Zngz_GAd105swbDsFdc9dq93io X-Authority-Analysis: v=2.4 cv=CYmdd7rl c=1 sm=1 tr=0 ts=6ae5095a cx=c_pps a=P2rfLEam3zuxRRdjJWA2cw==:117 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=x7bEGLp0ZPQA:10 a=A0y_DWxS2BwA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=azVShVRs0zEubeQ0wG0L:22 a=QACC7Yd5LT3gdyx-e0gA:9 a=QEXdDO2ut3YA:10 a=zgiPjhLxNE0A:10 a=ODZdjJIeia2B_SHc_B0f:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDMwMDA4NCBTYWx0ZWRfX5jWkmTGvdyI5 tFAb0PX0Rf9t1J640LaZ4Fmke3AEuZ/C7/4BeIkSumq7PmcZHUSKtpK/ajup92w/Mhve70nFAXY sZmbhbvq5cWujJsDTiJonXZazuL3GV1wF67/ZFg+X7Ngj0wJaZTlKCXwsm5hFkWa2YQbGGXI11x MeE1ehk3LsDCWqoIUraHjcMYNkfurqWdmQxNocP7wXh8pG59x0/VOo20JrJOVOVQH3xYzz0Ns3Q np7lDB+WideSUQAJhNrxAnNUYNIpp8VexVRV7JQeFq5gY+WrTC2xZSb/xQ9lROiXJteRR2Iv/H8 Pw+6H3dwyJTVxA4s/TxURSg6Tyc4m96p/+FlK8F5noTBl1wjoc0fJK2Kyup2vevpWPeVqPYocLx 7mEnkAIHZk+QIkPzjiKQp+hK5oXjS3IRLnf7G2oTpylgK4L+HRHHbLsqsNi18c8rkgDkW41fekj Ez1+5nVofnnMk9r7Dyw== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDMwMDA4NCBTYWx0ZWRfX+TohKtFKRiO8 6nv3ltnHEwvBXBkdLkEbX5p3u2Gf0bHT7JxnWbEK4+yNHZGA1mY4AjAY3OZx7zCUpRYOqIZHvcJ ekOZ57pCDSZdmnIc7oBqnl14r5sfQ824hZA97RKU1K3upzRBeCUv X-Proofpoint-Virus-Version: vendor=nai engine=6900 definitions=11951 signatures=596817 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 adultscore=0 bulkscore=10 malwarescore=0 suspectscore=0 impostorscore=10 priorityscore=1501 spamscore=0 clxscore=1015 lowpriorityscore=10 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610300000 definitions=main-2610300084 On 10/30/26 10:42 AM, David Hildenbrand (Arm) wrote: > On 10/30/26 11:50, Tal Zussman wrote: >> On Thu, Aug 06, 2026 at 01:14:38PM +0200, David Hildenbrand (Arm) wrote: >>> hwpoison code can end up calling min_order_for_split() without holding >>> the folio lock. There isn't really something that would prevent >>> concurrent folio split. Consequently folio->mapping can get set to >>> NULL after checking for "!folio->mapping", and if the compiler >>> reloads folio->mapping, mapping_min_folio_order() would try to >>> dereference NULL. >> >> Hi David, >> >> Did this patch ever make it in? > > If you ask this way ... I guess not? :D > :) > I can see if it still applies and resend + apply. That would be great, thanks!