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Thu, 12 Nov 2026 09:04:37 +0000 X-Mizu-Trace-ID: 8b0e325b35ab9706 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Thu, 12 Nov 2026 17:04:28 +0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/3] mm: gup: allow long-term pins of CMA-allocated HugeTLB folios To: "David Hildenbrand (Arm)" , Muchun Song Cc: osalvador@suse.de, akpm@linux-foundation.org, azpijr@gmail.com, Lance Yang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Qi Zheng References: <503c9f6d869e3206c6fd591de962c3d619b73825.1794379433.git.zhengqi.arch@bytedance.com> <80FED512-77D2-4D49-BAE5-745CE1F711CA@linux.dev> <1116fd15-a927-4f6e-a0ab-084bc36a90aa@linux.dev> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: hrizus8w9gwn9i87twsq1dz3fuu584mg X-Rspamd-Queue-Id: 054EF20002 X-Rspam-User: X-Rspamd-Server: rspam11 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-HE-Tag: 1794474278-5391 X-HE-Meta: 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 GgtqpgxO 6yVrPsinMWKmisi33LsBp9rODQkrPdHs5clOEThWpAEziPpWEZzYMvB+vZR9a1nJdFMlRwXLgjgrzd1zldyPyhl55L+E/dtOl+ccmKWZkmXbO42sEgH018DmQEsWTDfCyMmkNZx07je3pLcqDfsDaQSDzO29bEeu4ePL5Pk3R38zY4fq8zFchYMnLSaX2hRWzQDn8CIQXhl2peaOd5cH4rDHsuu4pRKGbfwcAaF9oxaR2X1iEOLFMVw6TZKpK2BPkBa35xBV4ZmrHvvFMUvdL4xqdyrvTbVeKtAkBQW8FbRiDP75AH16DOzaXP40F/M1QPRmLcz4dg/I23gg87DWhD2CfHu7rIoE50Rk4FKS/IVPCZ2pjOVx1YN8HOw== 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 11/12/26 4:49 PM, David Hildenbrand (Arm) wrote: > On 11/12/26 07:13, Qi Zheng wrote: >> >> >> On 11/11/26 3:42 PM, Muchun Song wrote: >>> >>> >>>> >>>> From: Qi Zheng >>>> >>>> Long-term pinning treats explicitly CMA-allocated HugeTLB folios as >>>> unpinnable, causing unnecessary migration or pinning failures. >>>> >>>> These folios already own their CMA bitmap ranges, and memory blocks >>> >>> Commit message needs updating to bitmap as well. >> >> Will do. >> >>> >>>> overlapping CMA areas cannot be offlined. Allow HugeTLB folios with >>>> HPG_cma to be pinned directly, including in ZONE_MOVABLE. >>>> >>>> Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages >>>> using cma") >>>> Cc: stable@vger.kernel.org >>>> Suggested-by: Muchun Song >>>> Signed-off-by: Qi Zheng >>>> Acked-by: Muchun Song >>>> Reviewed-by: Oscar Salvador >>>> Reviewed-by: Jose A. Perez de Azpillaga >>>> --- >>>> include/linux/mm.h | 29 +---------------------------- >>>> mm/gup.c           | 31 +++++++++++++++++++++++++++++++ >>>> 2 files changed, 32 insertions(+), 28 deletions(-) >>>> >>>> diff --git a/include/linux/mm.h b/include/linux/mm.h >>>> index b0da9be413098..47d1d96bfc7fd 100644 >>>> --- a/include/linux/mm.h >>>> +++ b/include/linux/mm.h >>>> @@ -2954,35 +2954,8 @@ static inline bool is_zero_folio(const struct folio >>>> *folio) >>>>     return is_zero_page(&folio->page); >>>> } >>>> >>>> -/* MIGRATE_CMA and ZONE_MOVABLE do not allow pin folios */ >>>> #ifdef CONFIG_MIGRATION >>>> -static inline bool folio_is_longterm_pinnable(struct folio *folio) >>> >>> I think David prefer to move this function first, then fix it in a separate >>> patch, >>> right? >> >> Hi David, is this what you mean? If so, I will split it into two patches >> for the v5. > > Let's try something that is more future-directed: cma should deal with > cma details. In the future we might implement something reasonable there. Aha, that does make more sense. Will do. Thanks, Qi > > diff --git a/include/linux/cma.h b/include/linux/cma.h > index 8555d38a97b1a..d829fd0355bae 100644 > --- a/include/linux/cma.h > +++ b/include/linux/cma.h > @@ -21,6 +21,9 @@ > #define CMA_MIN_ALIGNMENT_BYTES (PAGE_SIZE * CMA_MIN_ALIGNMENT_PAGES) > > struct cma; > +struct folio; > + > +bool cma_folio_is_longterm_pinnable(struct folio *folio); > > extern unsigned long totalcma_pages; > extern phys_addr_t cma_get_base(const struct cma *cma); > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 6af3b7008f1ad..5392e225cab9b 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3,6 +3,7 @@ > #define _LINUX_MM_H > > #include > +#include > #include > #include > #include > @@ -2975,7 +2976,10 @@ static inline bool is_zero_folio(const struct folio *folio) > return is_zero_page(&folio->page); > } > > -/* MIGRATE_CMA and ZONE_MOVABLE do not allow pin folios */ > +/* > + * MIGRATE_CMA and ZONE_MOVABLE folios cannot normally be long-term pinned. > + * CMA may allow pinning folios explicitly allocated from its areas. > + */ > #ifdef CONFIG_MIGRATION > static inline bool folio_is_longterm_pinnable(struct folio *folio) > { > @@ -2983,7 +2987,7 @@ static inline bool folio_is_longterm_pinnable(struct folio *folio) > int mt = folio_migratetype(folio); > > if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE) > - return false; > + return cma_folio_is_longterm_pinnable(folio); > #endif > /* The zero page can be "pinned" but gets special handling. */ > if (is_zero_folio(folio)) > diff --git a/mm/cma.c b/mm/cma.c > index 9ec1d1fd5dff5..b3bf0014a90f5 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -38,6 +39,16 @@ > struct cma cma_areas[MAX_CMA_AREAS]; > unsigned int cma_area_count; > > +bool cma_folio_is_longterm_pinnable(struct folio *folio) > +{ > + /* > + * Explicitly allocated CMA folios own their bitmap ranges and can be > + * pinned even in ZONE_MOVABLE, as CMA memory cannot be offlined. > + * For now, only HugeTLB tracks these allocations with a folio flag. > + */ > + return folio_test_hugetlb(folio) && folio_test_hugetlb_cma(folio); > +} > + > phys_addr_t cma_get_base(const struct cma *cma) > { > WARN_ON_ONCE(cma->nranges != 1);