From patchwork Wed Nov 2 19:12:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13028905 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7961C433FE for ; Wed, 2 Nov 2022 19:12:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3F72D8E0003; Wed, 2 Nov 2022 15:12:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3A7338E0001; Wed, 2 Nov 2022 15:12:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 26F6B8E0003; Wed, 2 Nov 2022 15:12:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 168BA8E0001 for ; Wed, 2 Nov 2022 15:12:26 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id DCB24140167 for ; Wed, 2 Nov 2022 19:12:25 +0000 (UTC) X-FDA: 80089448250.03.B1D30F5 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf21.hostedemail.com (Postfix) with ESMTP id 771F11C0005 for ; Wed, 2 Nov 2022 19:12:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667416345; 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=6YPbVJPY8MtPnMTid4uTdi1CU5/wNXrXzoHJaI5QF0k=; b=ZQHy1QacE7q3sVYT23SZvQPZM38jWNd9DQH4hR7ZnhuCrPGCvRX0+6gGFzKAuU/Q635yi4 pua6WakgP6gzf02FIKdqY7aZLbwEFPpGMrrHEL8zQALMO+XhFncGgXCwB2M5RKUJKxuGv0 hzQ3ydZ+IhojZXaWDpnf36hYj2vTaFA= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-542-rpR-vEwkMu-2AEpRHiq6RQ-1; Wed, 02 Nov 2022 15:12:19 -0400 X-MC-Unique: rpR-vEwkMu-2AEpRHiq6RQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3DD773804060; Wed, 2 Nov 2022 19:12:19 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.192.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5E840492CA5; Wed, 2 Nov 2022 19:12:15 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Linus Torvalds , Andrew Morton , Mel Gorman , Dave Chinner , Nadav Amit , Peter Xu , Andrea Arcangeli , Hugh Dickins , Vlastimil Babka , Michael Ellerman , Nicholas Piggin , Mike Rapoport , Anshuman Khandual Subject: [PATCH v1 1/6] mm/mprotect: allow clean exclusive anon pages to be writable Date: Wed, 2 Nov 2022 20:12:04 +0100 Message-Id: <20221102191209.289237-2-david@redhat.com> In-Reply-To: <20221102191209.289237-1-david@redhat.com> References: <20221102191209.289237-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=ZQHy1Qac; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667416345; a=rsa-sha256; cv=none; b=RQV+83PNg2j5GvdhkuCljwnNQn8FKrxAXavGkRu4ZVjM2s5QHi5OJwJGux+pZx6dZ90LRw G90/y0TQ3LAVr5wpqUT9/1KAc9/vchUJ1z7b+3R5rfJYk6uWNWPBXEBknGZOmxaWM4zSpo c5uoCUTnBoT4dNzjyMZWrZOmljtNEe4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667416345; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6YPbVJPY8MtPnMTid4uTdi1CU5/wNXrXzoHJaI5QF0k=; b=UgmDWBw+QGAGqlw7bZYdNO32KE1m2hJhp2lG9I9PvvGUE8HSk6J0Bwd6Ki7YtOtCa9fkwK qGAOQPdO2DMASpONmL/8Pf826/++5AYYfGbnfJ5xiGbL2YaIBe+D91ABUcI/qUYYGsL21w 0d0YaVREPI53XKTg4r4Xfthz3bkTvM0= X-Stat-Signature: a1npxx5px9hp7fcnr194wxjnjs9a1shj X-Rspamd-Queue-Id: 771F11C0005 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=ZQHy1Qac; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1667416345-720821 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Nadav Amit Anonymous pages might have the dirty bit clear, but this should not prevent mprotect from making them writable if they are exclusive. Therefore, skip the test whether the page is dirty in this case. Note that there are already other ways to get a writable PTE mapping an anonymous page that is clean: for example, via MADV_FREE. In an ideal world, we'd have a different indication from the FS whether writenotify is still required. Signed-off-by: Nadav Amit [ return directly; update description ] Signed-off-by: David Hildenbrand --- mm/mprotect.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 8d770855b591..86a28c0e190f 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -46,7 +46,7 @@ static inline bool can_change_pte_writable(struct vm_area_struct *vma, VM_BUG_ON(!(vma->vm_flags & VM_WRITE) || pte_write(pte)); - if (pte_protnone(pte) || !pte_dirty(pte)) + if (pte_protnone(pte)) return false; /* Do we need write faults for softdirty tracking? */ @@ -65,11 +65,10 @@ static inline bool can_change_pte_writable(struct vm_area_struct *vma, * the PT lock. */ page = vm_normal_page(vma, addr, pte); - if (!page || !PageAnon(page) || !PageAnonExclusive(page)) - return false; + return page && PageAnon(page) && PageAnonExclusive(page); } - return true; + return pte_dirty(pte); } static unsigned long change_pte_range(struct mmu_gather *tlb,