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Tue, 24 Sep 2024 03:17:20 -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 v5 2/2] mm: Allocate THP on hugezeropage wp-fault Date: Tue, 24 Sep 2024 15:46:54 +0530 Message-Id: <20240924101654.1777697-3-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240924101654.1777697-1-dev.jain@arm.com> References: <20240924101654.1777697-1-dev.jain@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5C0AD40014 X-Stat-Signature: ifyajwz3mnjehnj5m5uxjfbw718sktgd X-Rspam-User: X-HE-Tag: 1727173050-194666 X-HE-Meta: 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 CL+OBA9y asPw9j84va0lFwH10YTIRWFgw9YYA/OFM4SjlXGf60YRrgRNeoxDBSqaqMVcNiZg6WOprGqiduRUG+iKQGKD2zOxdiat0x/KpNJ4uTVC8gbAnEqDMs1+YPbslhHTKd9kAzU2xy5AUnPfwc4wjoJTEApSRVA== 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. Remember to flush TLB entry corresponding to the hugezeropage. In case of failure, fallback to splitting the PMD. Signed-off-by: Dev Jain Acked-by: David Hildenbrand Reviewed-by: Kefeng Wang --- mm/huge_memory.c | 44 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bdbf67c18f6c..fbb195bc2038 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1790,6 +1790,41 @@ 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 = vmf->address & HPAGE_PMD_MASK; + struct vm_area_struct *vma = vmf->vma; + struct mmu_notifier_range range; + struct folio *folio; + vm_fault_t ret = 0; + + folio = vma_alloc_anon_folio_pmd(vma, 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; + (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd); + map_anon_folio_pmd(folio, vmf->pmd, vma, haddr); + 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; @@ -1802,8 +1837,15 @@ 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); + + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + + /* Fallback to splitting PMD if THP cannot be allocated */ goto fallback; + } spin_lock(vmf->ptl);