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Tue, 10 Sep 2024 23:56:30 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org, david@redhat.com, willy@infradead.org, kirill.shutemov@linux.intel.com Cc: ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, mark.rutland@arm.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, jglisse@google.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dev Jain Subject: [PATCH v3 2/2] mm: Allocate THP on hugezeropage wp-fault Date: Wed, 11 Sep 2024 12:26:00 +0530 Message-Id: <20240911065600.1002644-3-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240911065600.1002644-1-dev.jain@arm.com> References: <20240911065600.1002644-1-dev.jain@arm.com> MIME-Version: 1.0 X-Stat-Signature: e8t4utrfwfbutb17skkq8ipby5dgtfc4 X-Rspamd-Queue-Id: 74C9214000D X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1726037800-349086 X-HE-Meta: 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 tA97Gt+5 IG7AkLHeydJRkp8FYUTpeb7CoesM3+6RTCRFlBYDsFllnuu2xuUaHuEdtIFryIt71RKwM6P8B224dwVifEFZN3w18Ce8elF0ErfdilmG80h1tFsYXd6JJmPNlTso+isK+7I0jZqOEyjRSCoakeA65Wmanlw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Introduce do_huge_zero_wp_pmd() to handle wp-fault on a hugezeropage and replace it with a PMD-mapped THP. Change the helper introduced in the previous patch to flush TLB entry corresponding to the hugezeropage. In case of failure, fallback to splitting the PMD. Signed-off-by: Dev Jain --- mm/huge_memory.c | 52 +++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 49 insertions(+), 3 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b96a1ff2bf40..3e28946a805f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -987,16 +987,20 @@ static void __pmd_thp_fault_success_stats(struct vm_area_struct *vma) static void map_pmd_thp(struct folio *folio, struct vm_fault *vmf, struct vm_area_struct *vma, unsigned long haddr) { - pmd_t entry; + pmd_t entry, old_pmd; + bool is_pmd_none = pmd_none(*vmf->pmd); entry = mk_huge_pmd(&folio->page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); folio_add_lru_vma(folio, vma); + if (!is_pmd_none) + old_pmd = pmdp_huge_clear_flush(vma, haddr, vmf->pmd); set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); - mm_inc_nr_ptes(vma->vm_mm); + if (is_pmd_none) + mm_inc_nr_ptes(vma->vm_mm); } static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) @@ -1576,6 +1580,41 @@ void huge_pmd_set_accessed(struct vm_fault *vmf) spin_unlock(vmf->ptl); } +static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf, unsigned long haddr) +{ + struct vm_area_struct *vma = vmf->vma; + gfp_t gfp = vma_thp_gfp_mask(vma); + struct mmu_notifier_range range; + struct folio *folio; + vm_fault_t ret = 0; + + folio = pmd_thp_fault_alloc(gfp, vma, haddr, vmf->address); + if (unlikely(!folio)) { + ret = VM_FAULT_FALLBACK; + goto out; + } + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, haddr, + haddr + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) + goto release; + ret = check_stable_address_space(vma->vm_mm); + if (ret) + goto release; + map_pmd_thp(folio, vmf, vma, haddr); + __pmd_thp_fault_success_stats(vma); + goto unlock; +release: + folio_put(folio); +unlock: + spin_unlock(vmf->ptl); + mmu_notifier_invalidate_range_end(&range); +out: + return ret; +} + vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) { const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; @@ -1588,8 +1627,15 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); VM_BUG_ON_VMA(!vma->anon_vma, vma); - if (is_huge_zero_pmd(orig_pmd)) + if (is_huge_zero_pmd(orig_pmd)) { + vm_fault_t ret = do_huge_zero_wp_pmd(vmf, haddr); + + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + + /* Fallback to splitting PMD if THP cannot be allocated */ goto fallback; + } spin_lock(vmf->ptl);