From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2AF691B85DD for ; Tue, 24 Sep 2024 13:13:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727183608; cv=none; b=ETqnGk+x6OihcEe98Ztc9F8XKJ885Yr1BNI2/tunnC+ciUZDJ1lgMRaXb17c0q8kmSrsl2pcrnyiGMZ7IXaXitP/l2SoKfeoVvyDMlDNt9+fzrRZjp4fgKxpEkI1ioLc4ve63IcoQQw4WqLs6lhns/z2y6JnRy8fOBKAVU4YkM4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727183608; c=relaxed/simple; bh=vFMlNR6E5c3x7AgCFp2QNq2hSCWb45w4t6NuuLZT1oc=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=nBHOTnab4XRMa+tq6GGlTgJKD0N4a6r8WZ5kpfv6ie0jkqPB3wAvaKYrqv6XKzc3UlMldkj+OfEJV/Arb77J1kCrwjhWx+gEAt3WPzDaFimh8Ca+HdjPrMQmaqJVd0hooc7jCdB/4jaqDydoDULHh4bY0H+bkIDcITD7hCjKW50= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4XCgJ60gHNzySFf; Tue, 24 Sep 2024 21:12:22 +0800 (CST) Received: from dggpemf100008.china.huawei.com (unknown [7.185.36.138]) by mail.maildlp.com (Postfix) with ESMTPS id 2D07D180AE8; Tue, 24 Sep 2024 21:13:22 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemf100008.china.huawei.com (7.185.36.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemf100008.china.huawei.com (7.185.36.138) 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); >