From nobody Fri Dec 19 14:36:48 2025 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 92A804B5A7 for ; Wed, 20 Dec 2023 22:45:21 +0000 (UTC) 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="OWTzei8a" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703112320; 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=TnwuPzh6vqXFM/JzpFan02MNs+lZlbvUqepTeKYzv68=; b=OWTzei8agv5dk0zqVJX+/pcd6pnLltQVoBLKipaTVAvbGQBEeu+Nr35K46XGpaHxtze2Ev xzN1ywi1tKVZO6MCLxdzPHKE4VNPqFU75lIB5YBIcnUEhik8CscQTxmA+S2BCbdO8EWo0Q lz3+Z+TzYv0IA1z04ww9SHbcPfzac9g= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-493-jRqZUihhOO6Rc9G1XGUnEA-1; Wed, 20 Dec 2023 17:45:18 -0500 X-MC-Unique: jRqZUihhOO6Rc9G1XGUnEA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (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 B24DC1C41B26; Wed, 20 Dec 2023 22:45:17 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.192.101]) by smtp.corp.redhat.com (Postfix) with ESMTP id 899DD40C6EB9; Wed, 20 Dec 2023 22:45:15 +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 v2 04/40] mm/rmap: introduce and use hugetlb_try_dup_anon_rmap() Date: Wed, 20 Dec 2023 23:44:28 +0100 Message-ID: <20231220224504.646757-5-david@redhat.com> In-Reply-To: <20231220224504.646757-1-david@redhat.com> References: <20231220224504.646757-1-david@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 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. Add sanity checks that we end up with the right folios in the right functions. Note that is_device_private_page() does not apply to hugetlb. Reviewed-by: Yin Fengwei Reviewed-by: Ryan Roberts Signed-off-by: David Hildenbrand Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Muchun Song --- include/linux/mm.h | 12 +++++++++--- include/linux/rmap.h | 18 ++++++++++++++++++ mm/hugetlb.c | 3 +-- 3 files changed, 28 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index b72bf25a45cfd..ae547b62f3252 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1964,15 +1964,21 @@ static inline bool page_maybe_dma_pinned(struct pag= e *page) * * The caller has to hold the PT lock and the vma->vm_mm->->write_protect_= seq. */ -static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, - struct page *page) +static inline bool folio_needs_cow_for_dma(struct vm_area_struct *vma, + struct folio *folio) { VM_BUG_ON(!(raw_read_seqcount(&vma->vm_mm->write_protect_seq) & 1)); =20 if (!test_bit(MMF_HAS_PINNED, &vma->vm_mm->flags)) return false; =20 - return page_maybe_dma_pinned(page); + return folio_maybe_dma_pinned(folio); +} + +static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, + struct page *page) +{ + return folio_needs_cow_for_dma(vma, page_folio(page)); } =20 /** diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 56900a16f41a6..5f26752de945c 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -211,6 +211,22 @@ void hugetlb_add_anon_rmap(struct folio *, struct vm_a= rea_struct *, void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *, unsigned long address); =20 +/* See page_try_dup_anon_rmap() */ +static inline int hugetlb_try_dup_anon_rmap(struct folio *folio, + struct vm_area_struct *vma) +{ + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + + if (PageAnonExclusive(&folio->page)) { + if (unlikely(folio_needs_cow_for_dma(vma, folio))) + return -EBUSY; + ClearPageAnonExclusive(&folio->page); + } + atomic_inc(&folio->_entire_mapcount); + return 0; +} + static inline void hugetlb_add_file_rmap(struct folio *folio) { VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); @@ -228,6 +244,8 @@ static inline void hugetlb_remove_rmap(struct folio *fo= lio) =20 static inline void __page_dup_rmap(struct page *page, bool compound) { + VM_WARN_ON(folio_test_hugetlb(page_folio(page))); + if (compound) { struct folio *folio =3D (struct folio *)page; =20 diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 57e8981879314..378e460a6ab41 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5409,8 +5409,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, st= ruct mm_struct *src, */ if (!folio_test_anon(pte_folio)) { hugetlb_add_file_rmap(pte_folio); - } else if (page_try_dup_anon_rmap(&pte_folio->page, - true, src_vma)) { + } else if (hugetlb_try_dup_anon_rmap(pte_folio, src_vma)) { pte_t src_pte_old =3D entry; struct folio *new_folio; =20 --=20 2.43.0