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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5DC41C48BC1 for ; Wed, 14 Feb 2024 20:53:06 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=G/ulD7TU; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=G/ulD7TU; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TZr4d0C8Cz3vtr for ; Thu, 15 Feb 2024 07:53:05 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=G/ulD7TU; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=G/ulD7TU; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.133.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=david@redhat.com; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 lists.ozlabs.org (Postfix) with ESMTPS id 4TZqwD1vxdz3vYD for ; Thu, 15 Feb 2024 07:45:48 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707943545; 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=fqQsnr9EFuS72Lg9egurC5IFPM5MYMM8dNEJpcWm/gk=; b=G/ulD7TUAyi5M5awyRkjJsEXKoq0nBx1kcbhMRnx/TObdXeNWkpv8HrWnJ5ymUzfTOyM/O JBTRf3iesIHcsbAuN4aqTmG6E4FpsLs42X7c8j1MD5eXB9KQKTIB8U9Rq4xUCOIxhSbEiO o18LVXAVVFSiSis1+ZEK9DHn1viV/eo= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707943545; 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=fqQsnr9EFuS72Lg9egurC5IFPM5MYMM8dNEJpcWm/gk=; b=G/ulD7TUAyi5M5awyRkjJsEXKoq0nBx1kcbhMRnx/TObdXeNWkpv8HrWnJ5ymUzfTOyM/O JBTRf3iesIHcsbAuN4aqTmG6E4FpsLs42X7c8j1MD5eXB9KQKTIB8U9Rq4xUCOIxhSbEiO o18LVXAVVFSiSis1+ZEK9DHn1viV/eo= 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-226-pgh-LenmOMa4VgIEuXmFnA-1; Wed, 14 Feb 2024 15:44:50 -0500 X-MC-Unique: pgh-LenmOMa4VgIEuXmFnA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (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 0A351185A782; Wed, 14 Feb 2024 20:44:49 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.194.174]) by smtp.corp.redhat.com (Postfix) with ESMTP id 438201C066AA; Wed, 14 Feb 2024 20:44:45 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Subject: [PATCH v3 02/10] mm/memory: handle !page case in zap_present_pte() separately Date: Wed, 14 Feb 2024 21:44:27 +0100 Message-ID: <20240214204435.167852-3-david@redhat.com> In-Reply-To: <20240214204435.167852-1-david@redhat.com> References: <20240214204435.167852-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , David Hildenbrand , Peter Zijlstra , Catalin Marinas , linux-mm@kvack.org, Alexander Gordeev , Will Deacon , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Vasily Gorbik , Matthew Wilcox , "Naveen N. Rao" , Christian Borntraeger , Ryan Roberts , Arnd Bergmann , Heiko Carstens , Nick Piggin , Yin Fengwei , Sven Schnelle , "Aneesh Kumar K.V" , Andrew Morton , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" We don't need uptodate accessed/dirty bits, so in theory we could replace ptep_get_and_clear_full() by an optimized ptep_clear_full() function. Let's rely on the provided pte. Further, there is no scenario where we would have to insert uffd-wp markers when zapping something that is not a normal page (i.e., zeropage). Add a sanity check to make sure this remains true. should_zap_folio() no longer has to handle NULL pointers. This change replaces 2/3 "!page/!folio" checks by a single "!page" one. Note that arch_check_zapped_pte() on x86-64 checks the HW-dirty bit to detect shadow stack entries. But for shadow stack entries, the HW dirty bit (in combination with non-writable PTEs) is set by software. So for the arch_check_zapped_pte() check, we don't have to sync against HW setting the HW dirty bit concurrently, it is always set. Reviewed-by: Ryan Roberts Signed-off-by: David Hildenbrand --- mm/memory.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 5b0dc33133a6..4da6923709b2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1497,10 +1497,6 @@ static inline bool should_zap_folio(struct zap_details *details, if (should_zap_cows(details)) return true; - /* E.g. the caller passes NULL for the case of a zero folio */ - if (!folio) - return true; - /* Otherwise we should only zap non-anon folios */ return !folio_test_anon(folio); } @@ -1538,24 +1534,28 @@ static inline void zap_present_pte(struct mmu_gather *tlb, int *rss, bool *force_flush, bool *force_break) { struct mm_struct *mm = tlb->mm; - struct folio *folio = NULL; bool delay_rmap = false; + struct folio *folio; struct page *page; page = vm_normal_page(vma, addr, ptent); - if (page) - folio = page_folio(page); + if (!page) { + /* We don't need up-to-date accessed/dirty bits. */ + ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); + arch_check_zapped_pte(vma, ptent); + tlb_remove_tlb_entry(tlb, pte, addr); + VM_WARN_ON_ONCE(userfaultfd_wp(vma)); + ksm_might_unmap_zero_page(mm, ptent); + return; + } + folio = page_folio(page); if (unlikely(!should_zap_folio(details, folio))) return; ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); arch_check_zapped_pte(vma, ptent); tlb_remove_tlb_entry(tlb, pte, addr); zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); - if (unlikely(!page)) { - ksm_might_unmap_zero_page(mm, ptent); - return; - } if (!folio_test_anon(folio)) { if (pte_dirty(ptent)) { -- 2.43.0