From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC864EDEC4F for ; Wed, 13 Sep 2023 12:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240712AbjIMMwb (ORCPT ); Wed, 13 Sep 2023 08:52:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240648AbjIMMwW (ORCPT ); Wed, 13 Sep 2023 08:52:22 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F2DB41BC8 for ; Wed, 13 Sep 2023 05:51:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694609489; 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=Z+qQSwZU5O6LoNzg+Y0KcgzyFROGp1piGCQLbieshoU=; b=TDI9gnm7p5CsZag3dSNEos0XRJbYI9BFE07jjbQZU4fl2m26IOFN8D/sslG+yZzbSOh2r2 WSHILd1vDnfCO7fpNzNnjAPiQ3kJuIhE/Iidwyz/qmTGVcvoA4YrhbTIJPTvfE0b/CgQTm XGcewk4cmosbvnJzQt2XwD7hRxr8K3I= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-18-4zJ54y7iMkaiv39wEbMctA-1; Wed, 13 Sep 2023 08:51:27 -0400 X-MC-Unique: 4zJ54y7iMkaiv39wEbMctA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6E9678011AD; Wed, 13 Sep 2023 12:51:27 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.193.225]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1F56421B20B1; Wed, 13 Sep 2023 12:51:26 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Mike Kravetz , Muchun Song Subject: [PATCH v1 5/6] mm/rmap: simplify PageAnonExclusive sanity checks when adding anon rmap Date: Wed, 13 Sep 2023 14:51:12 +0200 Message-ID: <20230913125113.313322-6-david@redhat.com> In-Reply-To: <20230913125113.313322-1-david@redhat.com> References: <20230913125113.313322-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Let's sanity-check PageAnonExclusive vs. mapcount in page_add_anon_rmap() and hugepage_add_anon_rmap() after setting PageAnonExclusive simply by re-reading the mapcounts. We can stop initializing the "first" variable in page_add_anon_rmap() and no longer need an atomic_inc_and_test() in hugepage_add_anon_rmap(). While at it, switch to VM_WARN_ON_FOLIO(). Signed-off-by: David Hildenbrand --- mm/rmap.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 489c142d073b..10d477a0991f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1199,7 +1199,7 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, atomic_t *mapped = &folio->_nr_pages_mapped; int nr = 0, nr_pmdmapped = 0; bool compound = flags & RMAP_COMPOUND; - bool first = true; + bool first; /* Is page being mapped by PTE? Is this its first map to be added? */ if (likely(!compound)) { @@ -1228,9 +1228,6 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, } } - VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); - VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); - if (nr_pmdmapped) __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped); if (nr) @@ -1252,6 +1249,8 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, } if (flags & RMAP_EXCLUSIVE) SetPageAnonExclusive(page); + VM_WARN_ON_FOLIO(page_mapcount(page) > 1 && PageAnonExclusive(page), + folio); mlock_vma_folio(folio, vma, compound); } @@ -2532,15 +2531,14 @@ void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address, rmap_t flags) { struct folio *folio = page_folio(page); - int first; VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); - first = atomic_inc_and_test(&folio->_entire_mapcount); - VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); - VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); + atomic_inc(&folio->_entire_mapcount); if (flags & RMAP_EXCLUSIVE) SetPageAnonExclusive(page); + VM_WARN_ON_FOLIO(folio_entire_mapcount(folio) > 1 && + PageAnonExclusive(page), folio); } void hugepage_add_new_anon_rmap(struct folio *folio, -- 2.41.0