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AJvYcCWKV7ClngeckWiT3Odz/NOw5q+LvuqVHXqHgHvMwzRz0r8yGQ9xZ0gjH+E3wwBsUH/H90PRFUH+Tg==@kvack.org X-Gm-Message-State: AOJu0YzoD3JHU6R8pVOgZfALxOWSyHrxwvKjPD5WDEyiFWyOTknUAxf9 bq6ZQ4OQD3asSGTQcvaZM3YmedLnKKu4mWvA4wLkmTvHGvX1w8H/415c8+KkYxmx4gIiqKhoNAC HCohzVfE7gB2LxSkdOiWbslRG9WykBZLTP75eP9a0 X-Gm-Gg: AZuq6aKm6ZO2ZP4Gn/t1Pcblq1qA2N/eD91ljlIzmfX/V+DFRX1gkvj3tbOP8GgL5ix o1ezDurP7cDdWFGXeoGwSr5YyfMCpZ8zTaGBntbE9X+E+DB6LSVedvHOgcHmGNo9TBRSOr/YsUk cmiCOHHITh05nT/JSze35vU06/s0T76Ymniu6LXQguO5EgoxtPSRADioe0meTlwxFxh06R4GhRE Ri0KaaTW0zW5EF67mQ79xC2l3m7aoYSUgW9jdOU9+skhID+QoYosk4o3QsaQIET2qepaB53GTGN VGC+nUJ+eJgoSAGdzj3+VSSHjHk= X-Received: by 2002:a05:600d:844a:10b0:477:95a8:3805 with SMTP id 5b1f17b1804b1-48055bca261mr205085e9.15.1769229746467; Fri, 23 Jan 2026 20:42:26 -0800 (PST) MIME-Version: 1.0 References: <20260116141157.29578-1-boudewijn@delta-utec.com> In-Reply-To: <20260116141157.29578-1-boudewijn@delta-utec.com> From: Jiaqi Yan Date: Fri, 23 Jan 2026 20:42:14 -0800 X-Gm-Features: AZwV_QgQHog8bttzRf6AzcHgHizMbtJX5B80VgdWnIgjFvKVXrtA08K1fLxEeRM Message-ID: Subject: Re: [PATCH] mm/page_alloc: Fix freeing of failed-split poisoned compound pages To: Boudewijn van der Heide , ziy@nvidia.com, linmiaohe@huawei.com Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, jackmanb@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, nao.horiguchi@gmail.com, osalvador@suse.de, surenb@google.com, vbabka@suse.cz Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 506331C0002 X-Stat-Signature: ekndkg4zjb8whjieq4iuz8w6hftk1d8o X-HE-Tag: 1769229748-279217 X-HE-Meta: U2FsdGVkX1/pppzfm/jsBbP4MXI15EZHXjbNzXGrBvkhzkM4SoXjuT6HhGGkLQBJFhbEdNiHSm09xB0Kt56U4FBnXrml8eiabOzCRFzCD3p6fWIEYF5kD887e1/XHcTMI2p9wTpFPrWIVVIf5B4n1XACN8kRcI9poVGUdpOFLBz7afFERQwebV0PJH/G0CjzdvRShTaPlVoFsskB+oYD6Z/m+NxFk3k+L6YHfk6otpgH6IJy0E7a/8ctbPlAV2PBK4Ckgh+Tx3RGQbQNEfv9EVLgXuAuvlRKqx4fVoYnqcAxPvb+FXPeFqJI4aji8JHuVhMuzzRWzCJrOa+8e1N+ZAvD9jEbBovh18YT+nIaw9JNuIXRnZ7JCx4MhSA5LlMT4rhFGMyEtIhH/WH8TXHuZgnaR53LsJwWXQVgShdsrALpbL1DmXdlj0SXselZinfMCE07uAQp3GV/WoKeZTC2jMLzzrc3H5mVAjmlg1I4yG0jo9VeYO2X+kwIxb7PMIiki7J51aEhl0KQvuN3KSav6LCa2IZPIH7eIr/0Oa9/HW61z8XhScbz+EKB6yTaiKBpnCf61lDUgHhRU4LnhT4ZUqnqpcQrnKfNjXmY2mOc1QTHtYKxysawfz/OeosjD9wexHw6ejKyWDdkmxRhS7n/steVQNjqtY56XCWWAPl1m7TVmY2G//CytllZBVETPsBTRJGAlwDTsxNaPoakc55+UrXtXMK5K0SZJM17K32FGK0U/mnM/WCjBRx8C7fprmgmGznvemkYB7zg6YMQ19Gz0AZ3XxhB5n0unDVwsn4kcgCmQNTd5Hq+moBucfM2qRncRTeKp1FVHBgaZXlk49vQmrz9XZE0rWIQ5oteqqfA6q4Fm+a4Awo7RZtG7TEFwCgFEPMvIvSb4kUz6S9FLIFb2Mq0TlN6LFMMYmgsH/Q96TjlhrfAjlykvgp7Ebz3cdqVQuEJqQm0yX1ChAKIz7F XMfaW5H8 Lj1WspfcS4baiVhm+YNO8mCt+B5qmcgyiEyA6L/S+Yb4CAvAZWREkZkgYiV4Gbo2441UPf9+R+Y8g4HI39XfRa11RQPc16mvF43vLMFBhrTtJCOcBGPTZYdJ5TUSf1UJBTJ0yUTpdYXjPFKnlWd4JoDiai1Zr/gibRxayOtAqFU4s6C90FXQdGQgdHmiF31kCjODwcmnuDeG+M2w3ZQPvF9UAHa8LMZwU0VaBg4a1QA2gPDPobGxhdZ5jVrexHTuiUgAKR2XvclDmHnKNyehmd48/o/OE51uu01IhWjmglqj/bLfLZh2CM+FG/kpfh4FAXW7Kla3wYxM9TdGaeX1ZsOIV59Gc0RlmaYvU0YBGuuFVjcFVoJXuCUfoavEV0IgT2FmRJoDvZRNgHizeQUnn7aWdHjg9P9jBjhfQFl7PA7CW+UxYx8UzJnCK3gWvwEV34QYzJFDouorxNMU= 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 Fri, Jan 16, 2026 at 6:12=E2=80=AFAM Boudewijn van der Heide wrote: > > Thanks Jiaqi for the feedback, that is very helpful. > (and thanks Miaohe for connecting the issues.) > > After going through the memory_failure(), > I can see it indeed puts the PG_HWPoison flag on the specific subpage poi= nter, > and therefore my fix won't work as-is. > > > > > > > Yes, this is also a problematic scenario for Hugetlb HugePage. And Ji= aqi works on > > > it now [1]. I think Jiaqi's patches might apply to THP scenario too. = Add @Jiaqi to > > > verify this. > > > > Yep, I think my work will also help solve the concern when > > try_to_split_thp_page() fails. > > Your fix makes a lot of sense for hugetlb, > as it linearly scans through all the pages. > From my understanding, > your fix also provides the perfect architecture for also checking THP, > though it doesn't yet cover the in-use THP case outlined. Oh, sorry I went ahead myself and assumed the split-failed folio would eventually be released to the buddy allocator at some point when userspace processes who owns/maps this THP are killed or exited. Zi and Miaohe, am I right about this? or do we need explicitly handle in-use and split-failed THP? > > For THP I would need to trace the failed-split paths more carefully, > to check where the equivalent path for THP would be. > > If there is work needed for THP, I'm happy to help. > Would you prefer I work on THP support as a separate follow-up patch, > after yours is merged, > or do you prefer to integrate it in your patch series? > > > > > > > [1]: https://lore.kernel.org/all/20260112004923.888429-1-jiaqiyan@goo= gle.com/ > > > > > > Thanks. > > > . > > Thanks, > Boudewijn