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Sun, 29 Sep 2024 22:28:37 -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 v6 2/2] mm: Allocate THP on hugezeropage wp-fault Date: Mon, 30 Sep 2024 10:58:12 +0530 Message-Id: <20240930052812.2627395-3-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240930052812.2627395-1-dev.jain@arm.com> References: <20240930052812.2627395-1-dev.jain@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B57B1A0007 X-Stat-Signature: 3gapgpiqxcnc4ifoo1qzc4seu5qzno1e X-Rspam-User: X-HE-Tag: 1727674126-21133 X-HE-Meta: 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 VtrU3CCp YBraQBGf+kVEmjfVmIrrl8Hd3uuqLoaYrSM8BnAnusa7rKZEX/F9gV3weC1ua26gVMrtoRyKX/+LP7kUAXmLxYFA4y4SqwD/vRM9aKuOmSEOZjvM3Hza+xDUKFb27MNnHPy6OjEvnPxVvNhE65+o/NLJdgogBL9t/A+eYYQZjwPbiGef+JLv1NcLtZc1WqJ9vhtQhqGPxYbxXLGI= 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. Acked-by: David Hildenbrand Reviewed-by: Kefeng Wang Signed-off-by: Dev Jain --- mm/huge_memory.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e3bcdbc9baa2..4677ed76953c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1790,6 +1790,38 @@ 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)) + return VM_FAULT_FALLBACK; + + 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); + return ret; +} + vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) { const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; @@ -1802,8 +1834,15 @@ 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);