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Mon, 7 Oct 2024 23:18:16 -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 v7 2/2] mm: Allocate THP on hugezeropage wp-fault Date: Tue, 8 Oct 2024 11:47:46 +0530 Message-Id: <20241008061746.285961-3-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241008061746.285961-1-dev.jain@arm.com> References: <20241008061746.285961-1-dev.jain@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: B0BB740004 X-Stat-Signature: fts6mcq6qzhjczg965kcsbnwmpygsdct X-HE-Tag: 1728368306-732780 X-HE-Meta: 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 g/e0wuFp cpZ3DCjx5cpOXa+2S8odfBs1z2DYVAx9RxsqdW0nBluLrseGCRb6h1+/yI574BI47g6DZF05bGp+Ugzg67MLLy9yILo6Y7XJ8cpfNFa9DgG0/NgmmfcBNTJFeySCYUYdvDdXizzucq/8vx29iURfgMQ4ANQYzQY/kN/QmTYeRvsz78Zkp7UwMJjZ2wBj+OEdRzIgUX0nKYzIzPyI= 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 e21c4f759e00..606ed782a15a 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);