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Tue, 24 Sep 2024 21:13:21 +0800 Message-ID: <7d21314c-9c53-4aa0-9a27-b07d21da429e@huawei.com> Date: Tue, 24 Sep 2024 21:13:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/2] mm: Allocate THP on hugezeropage wp-fault To: Dev Jain , , , , CC: , , , , , , , , , , , , , , , , , , , , , References: <20240924101654.1777697-1-dev.jain@arm.com> <20240924101654.1777697-3-dev.jain@arm.com> Content-Language: en-US From: Kefeng Wang In-Reply-To: <20240924101654.1777697-3-dev.jain@arm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemf100008.china.huawei.com (7.185.36.138) X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 26A851A0030 X-Stat-Signature: xkro7fk7eoumuroqnpgu51mbz6z9sgck X-Rspam-User: X-HE-Tag: 1727183605-586563 X-HE-Meta: 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 QuqFglDs 1Fcyao+Okw7XQ9TszrJWD92LMxYWuTzZqvt6WgbCnxbZu2XBFH0d2owzycvkW1ucAFogtK3l/Doj8ZPDGSX/IJ//YckQQoEWSKX7vuxL6YzSAZijVW4cbO4pOHtQBvL2sIFjDUyAW1WmGgAUBKgSsWM9z/kIneHOzRzMxQy97yZo4VwwcSAueLhCkQvCrJpdjDUmEbXlSgj4j1gBLqBRUmIGQaRiBt9AyP6+9HCg3AvdPYy9MkfPOJsqXnSeAxRzjMtBc 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: On 2024/9/24 18:16, Dev Jain wrote: > 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 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; I'd like to return VM_FAULT_FALLBACK if you re-post. Reviewed-by: Kefeng Wang > + 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); >