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Mon, 16 Sep 2024 02:43:56 -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-kernel@vger.kernel.org, linux-mm@kvack.org, Dev Jain Subject: [PATCH v4 2/2] mm: Allocate THP on hugezeropage wp-fault Date: Mon, 16 Sep 2024 15:13:09 +0530 Message-Id: <20240916094309.1226908-3-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240916094309.1226908-1-dev.jain@arm.com> References: <20240916094309.1226908-1-dev.jain@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: ECE5D180009 X-Stat-Signature: br7d6yp69anrydajd41uh7gw56pdx5oc X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1726479845-101941 X-HE-Meta: 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 pp0bEjKt hgnjiFrMzQ0LOlsKM2zolpsBEX8t18EmM2otIOBYQOdLczEt3ywqFdmOvy2oGwHQZ318+yPYGlQr1WUfEfHqaGLaX/zpghsZPEM26M0ebXGYQeqELo+vPYgPyX8cr0Z1DcdVFob5H+UlUtDySlQkPlk7ImA== 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 --- 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 cdc632b8dc9c..eac7f58729b3 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1796,6 +1796,41 @@ 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; @@ -1808,8 +1843,15 @@ 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);