From nobody Mon Dec 29 00:37:19 2025 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 CC132C4167B for ; Mon, 4 Dec 2023 14:22:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345233AbjLDOWH (ORCPT ); Mon, 4 Dec 2023 09:22:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345112AbjLDOV6 (ORCPT ); Mon, 4 Dec 2023 09:21:58 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F7EBDF for ; Mon, 4 Dec 2023 06:22:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701699723; 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=4nUQXJdzLDxn5x/X9wL3ukpxzJ+76ZeroIzXMEVl8GM=; b=IuZIPA1AcRPXNJDTi3f5+yulCD3ekcXjS5F2429w+2aJw4lTKEyAu9fRRPR1DaeHEjOm1c bv1LY16stx4u7+Yc1Y3C/D8PYDaShPgj4LOidJyRwCXI07h+nViAltMnIGH9OgXTSmaBy/ DX0nbVKZmNYpv3QIn3VnPdhuBbg9uUA= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-9-ssjzReYIPVSCXays4yclSw-1; Mon, 04 Dec 2023 09:21:58 -0500 X-MC-Unique: ssjzReYIPVSCXays4yclSw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id EA9F3101A590; Mon, 4 Dec 2023 14:21:57 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.195.87]) by smtp.corp.redhat.com (Postfix) with ESMTP id 572442026D4C; Mon, 4 Dec 2023 14:21:56 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Hugh Dickins , Ryan Roberts , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu Subject: [PATCH RFC 05/39] mm/rmap: introduce and use hugetlb_try_share_anon_rmap() Date: Mon, 4 Dec 2023 15:21:12 +0100 Message-ID: <20231204142146.91437-6-david@redhat.com> In-Reply-To: <20231204142146.91437-1-david@redhat.com> References: <20231204142146.91437-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" hugetlb rmap handling differs quite a lot from "ordinary" rmap code. For example, hugetlb currently only supports entire mappings, and treats any mapping as mapped using a single "logical PTE". Let's move it out of the way so we can overhaul our "ordinary" rmap. implementation/interface. So let's introduce and use hugetlb_try_dup_anon_rmap() to make all hugetlb handling use dedicated hugetlb_* rmap functions. Note that try_to_unmap_one() does not need care. Easy to spot because among all that nasty hugetlb special-casing in that function, we're not using set_huge_pte_at() on the anon path -- well, and that code assumes that we we would want to swapout. Signed-off-by: David Hildenbrand Reviewed-by: Yin Fengwei --- include/linux/rmap.h | 20 ++++++++++++++++++++ mm/rmap.c | 15 ++++++++++----- 2 files changed, 30 insertions(+), 5 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 8068c332e2ce5..3f38141b53b9d 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -223,6 +223,26 @@ static inline int hugetlb_try_dup_anon_rmap(struct fol= io *folio, return 0; } =20 +/* See page_try_share_anon_rmap() */ +static inline int hugetlb_try_share_anon_rmap(struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(!PageAnonExclusive(&folio->page), folio); + + /* See page_try_share_anon_rmap() */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb(); + + if (unlikely(folio_maybe_dma_pinned(folio))) + return -EBUSY; + ClearPageAnonExclusive(&folio->page); + + /* See page_try_share_anon_rmap() */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb__after_atomic(); + return 0; +} + static inline void hugetlb_add_file_rmap(struct folio *folio) { VM_WARN_ON_FOLIO(folio_test_anon(folio), folio); diff --git a/mm/rmap.c b/mm/rmap.c index 5037581b79ec6..2f1af3958e687 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2105,13 +2105,18 @@ static bool try_to_migrate_one(struct folio *folio,= struct vm_area_struct *vma, !anon_exclusive, subpage); =20 /* See page_try_share_anon_rmap(): clear PTE first. */ - if (anon_exclusive && - page_try_share_anon_rmap(subpage)) { - if (folio_test_hugetlb(folio)) + if (folio_test_hugetlb(folio)) { + if (anon_exclusive && + hugetlb_try_share_anon_rmap(folio)) { set_huge_pte_at(mm, address, pvmw.pte, pteval, hsz); - else - set_pte_at(mm, address, pvmw.pte, pteval); + ret =3D false; + page_vma_mapped_walk_done(&pvmw); + break; + } + } else if (anon_exclusive && + page_try_share_anon_rmap(page)) { + set_pte_at(mm, address, pvmw.pte, pteval); ret =3D false; page_vma_mapped_walk_done(&pvmw); break; --=20 2.41.0