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Fri, 06 Nov 2026 06:13:03 +0000 X-Mizu-Trace-ID: ff19274c30c44807 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Fri, 6 Nov 2026 14:12:56 +0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/4] mm: hugetlb: fix GFP mask propagation to CMA To: "Oscar Salvador (SUSE)" Cc: muchun.song@linux.dev, osalvador@suse.de, david@kernel.org, akpm@linux-foundation.org, azpijr@gmail.com, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Qi Zheng References: <1535887c-6be2-4415-b54e-2008e6e7a35c@linux.dev> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Stat-Signature: afq53wspyta4kpwchhig1wabsxr43xfh X-Spam-Status: No, score=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: D3D5EC0004 X-Rspam-User: X-HE-Tag: 1793945595-489459 X-HE-Meta: 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 yTcJUKlO 31emOKNbUCbzpaplpb1+RvAQjP0Y2jdXjbY0Xo+cnqvwC0TFs9ShaJKpBXKGRsodbji6K7sKoBSJzGBi7t7pzLqQ6d6xHe8L0GCKTEZcGeLxnYh5gEIQNy2VBDJUUOBE4JQS4upeZO9McXUFDNQbf0+sMMGP1iTNJNY8MXcTw4gxD/u3Xb3APTgZfV/rlHZxaR6dcJPxVJGhDePPytlsGCftzQIV8HBt782HWZnjsM5C+P7b3PPV2ltH4tTTF2d5ib3YvpGt5550kZAgarTDbbTGgwQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/6/26 1:50 PM, Oscar Salvador (SUSE) wrote: > On Fri, Nov 06, 2026 at 10:43:53AM +0800, Qi Zheng wrote: >> I'd still prefer to keep __GFP_COMP so that >> cma_alloc_frozen_compound() itself guarantees compound allocation, >> without requiring callers to supply the flag. > > Well, but aren't all callers hugetlb? And we already do supply __GFP_COMP there > for evident reasons. > And should that not be the case, and you want to catch someone who went rogue, > I would just place a WARN_ON_ONCE to catch it here, so we know who is not following > the rules. > > Makes sense? Ah, make sense. How about this: diff --git a/mm/cma.c b/mm/cma.c index 876635a56180e..45017ed876f76 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -935,7 +935,8 @@ struct page *cma_alloc_frozen(struct cma *cma, unsigned long count, struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order, gfp_t gfp) { - gfp |= __GFP_COMP | __GFP_NOWARN; + if (WARN_ON_ONCE(!(gfp & __GFP_COMP))) + return NULL; return __cma_alloc_frozen(cma, 1 << order, order, gfp); } > >