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AJvYcCUWFRLSuigDxfCAe5zsBPDaiCD64hyxBtp2R7RvvOZmX/jte7aGNwUln9LoVhJYWHZXcLr8/OyN6EHTsxsHfSJbd68iN6D9JrLgLRYH X-Gm-Message-State: AOJu0Yxo8xGVKFHUz9zM5h5qngbk88zO9kuqR0MxN3aA5shFbHHKx8kp lPEEI7QxebE9UYfCyUsdUr3IwKSi5gLYaqqGGhHItt4y72TjozpA X-Google-Smtp-Source: AGHT+IHuuLA3IkOVWnemUAiXi6DwNGqf6nD+qxo5av/4Kb4vZP8/N6Adb31SMqw2zaGmXf2b8MhZIQ== X-Received: by 2002:a05:6a20:8423:b0:1af:7646:fc14 with SMTP id adf61e73a8af0-1b2f151f841mr9176853637.0.1718021191815; Mon, 10 Jun 2024 05:06:31 -0700 (PDT) Received: from LancedeMBP.lan.lan ([2403:2c80:6::304c]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7043aa52899sm2182250b3a.25.2024.06.10.05.06.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jun 2024 05:06:31 -0700 (PDT) From: Lance Yang To: ioworker0@gmail.com Cc: 21cnbao@gmail.com, akpm@linux-foundation.org, baolin.wang@linux.alibaba.com, david@redhat.com, fengwei.yin@intel.com, libang.li@antgroup.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, maskray@google.com, mhocko@suse.com, minchan@kernel.org, peterx@redhat.com, ryan.roberts@arm.com, shy828301@gmail.com, sj@kernel.org, songmuchun@bytedance.com, wangkefeng.wang@huawei.com, willy@infradead.org, xiehuan09@gmail.com, ziy@nvidia.com, zokeefe@google.com Subject: [PATCH v7 3/4] mm/rmap: integrate PMD-mapped folio splitting into pagewalk loop Date: Mon, 10 Jun 2024 20:06:18 +0800 Message-Id: <20240610120618.66520-1-ioworker0@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20240610120209.66311-1-ioworker0@gmail.com> References: <20240610120209.66311-1-ioworker0@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In preparation for supporting try_to_unmap_one() to unmap PMD-mapped folios, start the pagewalk first, then call split_huge_pmd_address() to split the folio. Suggested-by: David Hildenbrand Suggested-by: Baolin Wang Signed-off-by: Lance Yang --- include/linux/huge_mm.h | 6 ++++++ mm/huge_memory.c | 42 +++++++++++++++++++++-------------------- mm/rmap.c | 21 +++++++++++++++------ 3 files changed, 43 insertions(+), 26 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 088d66a54643..4670c6ee118b 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -415,6 +415,9 @@ static inline bool thp_migration_supported(void) return IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION); } =20 +void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addre= ss, + pmd_t *pmd, bool freeze, struct folio *folio); + #else /* CONFIG_TRANSPARENT_HUGEPAGE */ =20 static inline bool folio_test_pmd_mappable(struct folio *folio) @@ -477,6 +480,9 @@ static inline void __split_huge_pmd(struct vm_area_stru= ct *vma, pmd_t *pmd, unsigned long address, bool freeze, struct folio *folio) {} static inline void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, bool freeze, struct folio *folio) {} +static inline void split_huge_pmd_locked(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmd, + bool freeze, struct folio *folio) {} =20 #define split_huge_pud(__vma, __pmd, __address) \ do { } while (0) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e6d26c2eb670..d2697cc8f9d4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2581,6 +2581,27 @@ static void __split_huge_pmd_locked(struct vm_area_s= truct *vma, pmd_t *pmd, pmd_populate(mm, pmd, pgtable); } =20 +void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addre= ss, + pmd_t *pmd, bool freeze, struct folio *folio) +{ + VM_WARN_ON_ONCE(folio && !folio_test_pmd_mappable(folio)); + VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); + VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); + VM_BUG_ON(freeze && !folio); + + /* + * When the caller requests to set up a migration entry, we + * require a folio to check the PMD against. Otherwise, there + * is a risk of replacing the wrong folio. + */ + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || + is_pmd_migration_entry(*pmd)) { + if (folio && folio !=3D pmd_folio(*pmd)) + return; + __split_huge_pmd_locked(vma, pmd, address, freeze); + } +} + void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, unsigned long address, bool freeze, struct folio *folio) { @@ -2592,26 +2613,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pm= d_t *pmd, (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); mmu_notifier_invalidate_range_start(&range); ptl =3D pmd_lock(vma->vm_mm, pmd); - - /* - * If caller asks to setup a migration entry, we need a folio to check - * pmd against. Otherwise we can end up replacing wrong folio. - */ - VM_BUG_ON(freeze && !folio); - VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); - - if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || - is_pmd_migration_entry(*pmd)) { - /* - * It's safe to call pmd_page when folio is set because it's - * guaranteed that pmd is present. - */ - if (folio && folio !=3D pmd_folio(*pmd)) - goto out; - __split_huge_pmd_locked(vma, pmd, range.start, freeze); - } - -out: + split_huge_pmd_locked(vma, range.start, pmd, freeze, folio); spin_unlock(ptl); mmu_notifier_invalidate_range_end(&range); } diff --git a/mm/rmap.c b/mm/rmap.c index ddffa30c79fb..b77f88695588 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1640,9 +1640,6 @@ static bool try_to_unmap_one(struct folio *folio, str= uct vm_area_struct *vma, if (flags & TTU_SYNC) pvmw.flags =3D PVMW_SYNC; =20 - if (flags & TTU_SPLIT_HUGE_PMD) - split_huge_pmd_address(vma, address, false, folio); - /* * For THP, we have to assume the worse case ie pmd for invalidation. * For hugetlb, it could be much worse if we need to do pud @@ -1668,9 +1665,6 @@ static bool try_to_unmap_one(struct folio *folio, str= uct vm_area_struct *vma, mmu_notifier_invalidate_range_start(&range); =20 while (page_vma_mapped_walk(&pvmw)) { - /* Unexpected PMD-mapped THP? */ - VM_BUG_ON_FOLIO(!pvmw.pte, folio); - /* * If the folio is in an mlock()d vma, we must not swap it out. */ @@ -1682,6 +1676,21 @@ static bool try_to_unmap_one(struct folio *folio, st= ruct vm_area_struct *vma, goto walk_done_err; } =20 + if (!pvmw.pte && (flags & TTU_SPLIT_HUGE_PMD)) { + /* + * We temporarily have to drop the PTL and start once + * again from that now-PTE-mapped page table. + */ + split_huge_pmd_locked(vma, pvmw.address, pvmw.pmd, + false, folio); + flags &=3D ~TTU_SPLIT_HUGE_PMD; + page_vma_mapped_walk_restart(&pvmw); + continue; + } + + /* Unexpected PMD-mapped THP? */ + VM_BUG_ON_FOLIO(!pvmw.pte, folio); + pfn =3D pte_pfn(ptep_get(pvmw.pte)); subpage =3D folio_page(folio, pfn - folio_pfn(folio)); address =3D pvmw.address; --=20 2.33.1