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b=E/+7iNKIdaG5gbWEYpyg2UfFr94ke15gdduH9urZWVzhEh582YL5KB6iGOai6sqe3 cZ2PdRf+mJF2g6ww9THusLf2cZDLNNRMGTFPBpci2J/c4LCshj8YzluBSYUG6KsVNu c8kuxuccSBJmLZgvibKE8ERHoZzsyHD5R1LR3gDpJ+Ea1x7KWsqIr7MJmfqby3tBMP 2WWa3dKF3mYKz+GOgThScHb95M63t0DMrasydXIByoxJSxcVIlIa1TVhPNKU/OyacN 9F6/wup/1n0l1Sy8gR1UVt5JOOiSZYBtsVgVliJPq7wQSJkbwxYZ3fVeBTrCfS8Mrb XKGBtAWP2BOGQ== Date: Sat, 7 Nov 2026 18:02:53 +0100 From: "Oscar Salvador (SUSE)" To: Qi Zheng 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, Qi Zheng , stable@vger.kernel.org Subject: Re: [PATCH v3 3/3] mm: hugetlb: fix GFP mask propagation to CMA Message-ID: References: <61ee04513d6cac32347ebec9b295025b8a1f07ca.1794046188.git.zhengqi.arch@bytedance.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <61ee04513d6cac32347ebec9b295025b8a1f07ca.1794046188.git.zhengqi.arch@bytedance.com> X-Stat-Signature: fai7oky1qzmifpam4q4qtxeh83pezh7n X-Rspam-User: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: EFC5940003 X-HE-Tag: 1794070979-439062 X-HE-Meta: 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 R7BfRw2K dkTWMHZ4HgCPUp1RZBiNHC2kt09RIS8KP89z8Jp/gdPpaMi/RyJxehXSaUn93LCcaz9Sbgq3FkSrJamGc3ZMNHl5PE6XfwXc40SLmks/JCzukuxZAyp+eIZmqC7/iCbdbeEzEyCLAjCkO/Skhh1K1vnE/udQITWeUKAAGxzR9yVxdfem94xzNe5NCEzjiW4l+/TKN/bNo9SpQmCAIsMxlrxWTiupfhNTs/uxk8USqD1JYgumpv2BrXyZMKjSTBd5LOEE1aA3IvhUoa4CxVOuWwmmq5CbaiUOJQlkM 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 Sat, Nov 07, 2026 at 06:30:47PM +0800, Qi Zheng wrote: > From: Qi Zheng > > cma_alloc_frozen_compound() uses GFP_KERNEL, allowing direct reclaim > during the first MPOL_PREFERRED_MANY allocation attempt even though > the caller clears __GFP_DIRECT_RECLAIM. > > Pass the caller's GFP mask through the helper so CMA respects its > reclaim constraints when trying the preferred nodes. > > Fixes: 9bda131c6093 ("mm: cma: add cma_alloc_frozen{_compound}()") > Cc: stable@vger.kernel.org > Signed-off-by: Qi Zheng > Acked-by: Muchun Song > Reviewed-by: Jose A. Perez de Azpillaga Reviewed-by: Oscar Salvador (SUSE) A comment below: > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -933,9 +933,10 @@ struct page *cma_alloc_frozen(struct cma *cma, unsigned long count, > return __cma_alloc_frozen(cma, count, align, gfp); > } > > -struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order) > +struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order, gfp_t gfp) > { > - gfp_t gfp = GFP_KERNEL | __GFP_COMP | __GFP_NOWARN; > + if (WARN_ON_ONCE(!(gfp & __GFP_COMP))) > + return NULL; I think this needs a comment explaining why we are checking for __GFP_COMP, because it might not be obvious to the casual reader. Something like: "The only caller of cma_alloc_frozen_compound() is hugetlb, and hugetlb constructs its gfp mask via htlb_alloc_mask(), which already sets __GFP_COMP. Check here for usecases bypassing htlb_alloc_mask()." Maybe in the future we do have some other users of this function which are outside of the hugetlb realm, but if we are propagating the gfp mask down the chain to this point, we do have to check that those users are also setting __GFP_COMP. -- Oscar Salvador SUSE Labs