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Fri, 11 Sep 2026 02:41:16 +0000 X-Mizu-Trace-ID: d64be4f82663bc04 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.700.51.1.1\)) Subject: Re: [PATCH] mm/hugetlb: account for allowed nodes when gathering surplus pages From: Muchun Song In-Reply-To: <20260910152026.5bcf5c5d7f1ecdcb0147ceaf@linux-foundation.org> Date: Fri, 11 Sep 2026 10:41:01 +0800 Cc: osalvador@suse.de, linux-mm@kvack.org, david@kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <35D58CFB-BC97-4245-A387-DB3077E395C3@linux.dev> References: <20260909074642.7308-1-yehuaisheng@open-hieco.net> <8A0F6014-4E2C-4F07-9732-2DF32418B986@linux.dev> <20260910152026.5bcf5c5d7f1ecdcb0147ceaf@linux-foundation.org> To: Andrew Morton , Huaisheng Ye X-Mailer: Apple Mail (2.3864.700.51.1.1) X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E2B7F40003 X-Stat-Signature: jocha9f4b6gna866rnrmct84mtbrm6kf X-Rspam-User: X-HE-Tag: 1789094479-346779 X-HE-Meta: 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 7/ECMH8Q dZOzUqyak0yAg2WoY7eecVPvOq3ond0HMTKBO/AmjxCy+4A9I+8gHaQHfmbEnEZdMOrlvXUIsWwcgYxidPtgWGAmT/nr+nx/T0w4Mp1qoYfTjtx22A+VEZI6Xsd5wgfTIiU2MoG6d7IgZApZuYVbY7i98eXxkQqzGHZBpDMp16vtZD5A5iRcZQ/oUT/JTKqzQWxuII4TUa8xGSLg1vv4NQ56hXI5xPOYL9pLR5K52RwwdqHnqn1YzEoR1pNxLK6zWlBKMLS1YZMHKN5vO2KjnFjqrvvFgk5JR/AaD+rlC5CZFL4pWI3ZCC5ZmiS3pxk7KBYbWWorg4Zy+mTqbEYaLNk38hliDGeKPgKjKUVIPttLLCogudDbqbfp+H4P1R0+oZocq Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Sep 11, 2026, at 06:20, Andrew Morton = wrote: >=20 > On Thu, 10 Sep 2026 16:48:56 +0800 Muchun Song = wrote: >=20 >>> This fixes hugetlb mappings when, for example, a task runs with >>> MPOL_BIND on Node 1 while the existing free huge pages are on Node = 0. >>>=20 >>> Similar issue also could be found in ltp if the free pages of global = pool >>> reside outside the nodes allowed by the application. >>> # cd ltp/testcases/kernel/mem/hugetlb/hugemmap/ >>> # numactl --cpunodebind=3D0 --membind=3D1 ./hugemmap10 >>>=20 >>> Signed-off-by: Huaisheng Ye >>=20 >> Acked-by: Muchun Song >=20 > Should we backport this? >=20 > If so, a Fixes: target would be helpful. I believe the fix should be e4e574b767ba ("hugetlb: Try to grow hugetlb pool for MAP_SHARED mappings"). This commit was introduced back in 2007. Regarding the impact of this issue, I consulted an AI: Severity: Medium Impact: valid HugeTLB mappings can be rejected with ENOMEM Scope: NUMA + cpuset/MPOL_BIND + nr_overcommit_hugepages Risk: availability/configuration failure, no data corruption The fact that it has only been triggered after such a long time also precisely shows how uncommon its configuration is. I expect that backporting may encounter some conflicts. In the absence of clear user feedback, I personally suggest not doing a backport. Of course, as the author of this patch, you could also provide more information, for example, whether it was discovered as a real issue in a production environment, so as to decide whether to proceed with a backport. Thanks.=