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Mon, 09 Nov 2026 03:11:05 +0000 X-Mizu-Trace-ID: 8422819e0d5f8816 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Mon, 9 Nov 2026 11:10:56 +0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/3] 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: <61ee04513d6cac32347ebec9b295025b8a1f07ca.1794046188.git.zhengqi.arch@bytedance.com> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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-Server: rspam09 X-Stat-Signature: iuxc7cyuazpm97k1bodmoacfc84sqxqf X-Rspamd-Queue-Id: D75F540005 X-Rspam-User: X-HE-Tag: 1794193866-935474 X-HE-Meta: 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 OtDF0fQF QWE8vxfmzix+wipv6xbNCM2JhWMV7/FEMSd7O2+7fHaIhWsgdC1tiQ0ST5maELCZvqrfaXpW8nTaCnsyDW4zj2KOQEXReXfHsKUuh288712JeitLnR2Tql7ZJ6F6nDdhW1z5XDceA43p6bTbqlMGy+ES76lko2u2jrJ59QaCsPaGPoAHoY+OMIzEC7McJDODTd0iAMKibFwL6W2Y+SpLf6tehO5nWpe9Aaupdlk0wvBUM+MkqMLCoQ6aSgwHNGGWdTzI7mK+y0Ddg1zlUevR4vmTg+hbEMOH78zvXyIOT9qVszZM72ICX5uR35M7EgqewFLOeg2k96ZvWS/wMggbmYcEoXw== 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 11/8/26 1:02 AM, Oscar Salvador (SUSE) wrote: > 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()." OK, will add this comment. Thanks, Qi > > > 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. > > >