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h=Date:From:To:Cc:Subject:In-Reply-To:References; b=BqER6ii8rP6FRY/NkYYyEQucd0+AtYHZb1aVAv1nJaet7sjRY4DvKpaScwlj6hH70 STxclYdXzNPEPjz9DJj4oroJ6inTBGt7aZVWKnVRSYS5lKOnRsujg1sn4T7GmDL7k4 df3AjAXRo6tPZOQYDAS0DHAiNu8DU7i9Ij23zig8= Date: Mon, 10 Aug 2026 15:36:28 -0700 From: Andrew Morton To: Sourav Panda Cc: Muchun Song , osalvador@suse.de, usama.arif@linux.dev, shakeel.butt@linux.dev, wangkefeng.wang@huawei.com, anshuman.khandual@arm.com, david@kernel.org, surenb@google.com, fvdl@google.com, gthelen@google.com, hannes@cmpxchg.org, riel@surriel.com, sj@kernel.org, vbabka@suse.cz, mhocko@suse.com, bjackman@google.com, zi.yan@sent.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5] mm/hugetlb_cma: Fix null nodemask dereference in hugetlb_cma_alloc_frozen_folio Message-Id: <20260810153628.c4049163bd92b5ce3d3d7d99@linux-foundation.org> In-Reply-To: References: <20260809043250.2917406-1-souravpanda@google.com> <60440F8D-5EE8-4254-9057-5FAD09B5D1FF@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4A47C80012 X-Stat-Signature: qudtkhem1nfxnujrb7rjpyi84wramf8p X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1786401391-591073 X-HE-Meta: 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 twUiWI88 0MSAZaE7pRfil0iNsNithw63ffhCPCiCsEnWquFHOXV7lJUeZRrnrAeAQbou6kbONAlnEWeJ2dawz9SErPKRzROUiZbXx4B2STpWP5U+DJAdUpQVMucwLiuuvCSLtEj+owJdSdKrHzLXtYuuBOENpDolX68lMpu0y9M14LOuZbQGjsrLIm1iie5tuXuTtvZZ0aDJe0oF1RL2ObLXK2wdqb8krRN8GBzxtLuaQnguMzzAliOk9AY/aLWQhVKVeRgnoCU9+yeCB2pN/2bhzsvZf/R+GBliSl8MnRZfj28KraCSDJe36ajB31IPHSFklhIyc3NrL0foSbCUtWXmwQ3jdA3h7oKblPUBUd8QYwuzOuLpt51A9/zgB48TSOhPhy5bXwrTF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 9 Aug 2026 23:39:22 -0700 Sourav Panda wrote: > > That way, we can remove the 'if (!page)' check here. > > Sure thing! Thanks! I shall send this tomorrow noon (PST) since I am > OOO starting Thursday. Sashiko said a thing - I don't think it reported this against previous iterations: https://sashiko.dev/#/patchset/20260726072935.3513996-1-souravpanda@google.com I'll add this v4->v5 update to mm-hotfixes-unstable, assuming it gets us a bit closer to the final version. --- a/mm/hugetlb_cma.c~mm-hugetlb_cma-fix-null-nodemask-dereference-in-hugetlb_cma_alloc_frozen_folio-v5 +++ a/mm/hugetlb_cma.c @@ -3,6 +3,7 @@ #include #include #include +#include #include #include @@ -30,12 +31,21 @@ struct folio *hugetlb_cma_alloc_frozen_f int node; struct folio *folio; struct page *page = NULL; + nodemask_t local_node_mask; if (!hugetlb_cma_size) return NULL; - if (!nodemask) - nodemask = &node_states[N_MEMORY]; + if (!nodemask) { + unsigned int cpuset_mems_cookie; + + do { + cpuset_mems_cookie = read_mems_allowed_begin(); + local_node_mask = cpuset_current_mems_allowed; + } while (read_mems_allowed_retry(cpuset_mems_cookie)); + + nodemask = &local_node_mask; + } if (hugetlb_cma[nid] && node_isset(nid, *nodemask)) page = cma_alloc_frozen_compound(hugetlb_cma[nid], order); _