From patchwork Fri Aug 2 15:55:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13751759 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 6B5921A34AA for ; Fri, 2 Aug 2024 15:56:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722614214; cv=none; b=Qhf08HwBsRtZD/2GxkgxSJVEh3lGZWoTCHBZYrtnFAp5fj+k9lVS1ERb2H16umxP5k62vr7KhSVE7ex9E0ipSqgLweIkhPCMl7M66I2V49CFeYbzPQ3xbqhUWp/VROyJFQQ3dNoeF9KC8ZpNukn+ShIHW/jKHKmCZcZsdhiCPxw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722614214; c=relaxed/simple; bh=B9QpgUZqHBSgII4REwP9lD0/53JlrVZdILJpl6GeaCQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GBv7747G1gASF+PgVUKa3Mm/YOSIr1mU60ZSsWl887xCx1SDevEjTYe/B3Zmdzb/oEQOqbn3YxQFn5vgwB9N9YGo9J4Bz2O/4M+ZDpn3wBEHSDD+OAwyVL+ojw/HcFak4tmpAKGbr/SiPbEbvnQ7zJtyjdPgXp/3ejGwrbuqfcQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=HhTudOSc; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HhTudOSc" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722614211; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XisBOloUEP3qStGU5kEnvOleMULjhsDMvLI1Qb38ywI=; b=HhTudOSczoDCzNBQBnIpia1CQZtRqjMaQQvctcz8uWfl66KLPLUyn1ol+K/k191SmfJMPC dNrmVHXMqvC+ubNoXK0PsnTG0RTa8SC64T5iDnWwQ16YMJtictZtzwmkevfTyKqs+6yRnt Hl2lreAjSkmNVDvvDQGeRkcDoFO/0aE= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-533-7fMx_I3IMvS20EQpewJYGQ-1; Fri, 02 Aug 2024 11:56:48 -0400 X-MC-Unique: 7fMx_I3IMvS20EQpewJYGQ-1 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 833C51955D4D; Fri, 2 Aug 2024 15:56:45 +0000 (UTC) Received: from t14s.redhat.com (unknown [10.39.192.113]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B30F4300018D; Fri, 2 Aug 2024 15:56:39 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Jonathan Corbet , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Gerald Schaefer Subject: [PATCH v1 11/11] mm/ksm: convert break_ksm() from walk_page_range_vma() to folio_walk Date: Fri, 2 Aug 2024 17:55:24 +0200 Message-ID: <20240802155524.517137-12-david@redhat.com> In-Reply-To: <20240802155524.517137-1-david@redhat.com> References: <20240802155524.517137-1-david@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Let's simplify by reusing folio_walk. Keep the existing behavior by handling migration entries and zeropages. Signed-off-by: David Hildenbrand --- mm/ksm.c | 63 ++++++++++++++------------------------------------------ 1 file changed, 16 insertions(+), 47 deletions(-) diff --git a/mm/ksm.c b/mm/ksm.c index 0f5b2bba4ef0..8e53666bc7b0 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -608,47 +608,6 @@ static inline bool ksm_test_exit(struct mm_struct *mm) return atomic_read(&mm->mm_users) == 0; } -static int break_ksm_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long next, - struct mm_walk *walk) -{ - struct page *page = NULL; - spinlock_t *ptl; - pte_t *pte; - pte_t ptent; - int ret; - - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); - if (!pte) - return 0; - ptent = ptep_get(pte); - if (pte_present(ptent)) { - page = vm_normal_page(walk->vma, addr, ptent); - } else if (!pte_none(ptent)) { - swp_entry_t entry = pte_to_swp_entry(ptent); - - /* - * As KSM pages remain KSM pages until freed, no need to wait - * here for migration to end. - */ - if (is_migration_entry(entry)) - page = pfn_swap_entry_to_page(entry); - } - /* return 1 if the page is an normal ksm page or KSM-placed zero page */ - ret = (page && PageKsm(page)) || is_ksm_zero_pte(ptent); - pte_unmap_unlock(pte, ptl); - return ret; -} - -static const struct mm_walk_ops break_ksm_ops = { - .pmd_entry = break_ksm_pmd_entry, - .walk_lock = PGWALK_RDLOCK, -}; - -static const struct mm_walk_ops break_ksm_lock_vma_ops = { - .pmd_entry = break_ksm_pmd_entry, - .walk_lock = PGWALK_WRLOCK, -}; - /* * We use break_ksm to break COW on a ksm page by triggering unsharing, * such that the ksm page will get replaced by an exclusive anonymous page. @@ -665,16 +624,26 @@ static const struct mm_walk_ops break_ksm_lock_vma_ops = { static int break_ksm(struct vm_area_struct *vma, unsigned long addr, bool lock_vma) { vm_fault_t ret = 0; - const struct mm_walk_ops *ops = lock_vma ? - &break_ksm_lock_vma_ops : &break_ksm_ops; + + if (lock_vma) + vma_start_write(vma); do { - int ksm_page; + bool ksm_page = false; + struct folio_walk fw; + struct folio *folio; cond_resched(); - ksm_page = walk_page_range_vma(vma, addr, addr + 1, ops, NULL); - if (WARN_ON_ONCE(ksm_page < 0)) - return ksm_page; + folio = folio_walk_start(&fw, vma, addr, + FW_MIGRATION | FW_ZEROPAGE); + if (folio) { + /* Small folio implies FW_LEVEL_PTE. */ + if (!folio_test_large(folio) && + (folio_test_ksm(folio) || is_ksm_zero_pte(fw.pte))) + ksm_page = true; + folio_walk_end(&fw, vma); + } + if (!ksm_page) return 0; ret = handle_mm_fault(vma, addr,