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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DA6FC00A89 for ; Mon, 2 Nov 2020 15:16:18 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7D4EC21556 for ; Mon, 2 Nov 2020 15:16:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="U5iA6iZ+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D4EC21556 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4CPxMK5XdkzDqPf for ; Tue, 3 Nov 2020 02:16:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=rppt@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=default header.b=U5iA6iZ+; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4CPxHs3L5RzDqQj for ; Tue, 3 Nov 2020 02:13:13 +1100 (AEDT) Received: from kernel.org (unknown [87.71.17.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 97C3A22258; Mon, 2 Nov 2020 15:13:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604329990; bh=pQm13rJ0TtLsoFHOZA52H/TzTWUyG6xri7XGlle4HPo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=U5iA6iZ+4RrbBTruBVP23DAtPFm6+kceLiKQw3J0W+zg1uOK+4S4JJxuhMMUqU1YR AbaxuhUr3wcVgMFL7UiNf9Rgt38tsM1oxGu8FMS5KMZthwA6c6ykTjZZtEvaQ3kHdo qOQc20cDKQCRHjZYM2XM4fU6aSAxgj4DgVoNXSRU= Date: Mon, 2 Nov 2020 17:12:56 +0200 From: Mike Rapoport To: David Hildenbrand Subject: Re: [PATCH v3 2/4] PM: hibernate: make direct map manipulations more explicit Message-ID: <20201102151256.GA4879@kernel.org> References: <20201101170815.9795-1-rppt@kernel.org> <20201101170815.9795-3-rppt@kernel.org> <55cd2a4a-cfa8-d420-66b3-a25fcdd9b876@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55cd2a4a-cfa8-d420-66b3-a25fcdd9b876@redhat.com> 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: "Rafael J . Wysocki" , Peter Zijlstra , Dave Hansen , linux-mm@kvack.org, Paul Mackerras , Pavel Machek , "H. Peter Anvin" , sparclinux@vger.kernel.org, Christoph Lameter , Will Deacon , linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, x86@kernel.org, Mike Rapoport , Christian Borntraeger , Ingo Molnar , Catalin Marinas , Len Brown , Albert Ou , Vasily Gorbik , linux-pm@vger.kernel.org, Heiko Carstens , David Rientjes , Borislav Petkov , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Thomas Gleixner , Joonsoo Kim , linux-arm-kernel@lists.infradead.org, "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Pekka Enberg , Palmer Dabbelt , Andrew Morton , "Edgecombe, Rick P" , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Nov 02, 2020 at 10:19:36AM +0100, David Hildenbrand wrote: > On 01.11.20 18:08, Mike Rapoport wrote: > > From: Mike Rapoport > > > > When DEBUG_PAGEALLOC or ARCH_HAS_SET_DIRECT_MAP is enabled a page may be > > not present in the direct map and has to be explicitly mapped before it > > could be copied. > > > > Introduce hibernate_map_page() that will explicitly use > > set_direct_map_{default,invalid}_noflush() for ARCH_HAS_SET_DIRECT_MAP case > > and debug_pagealloc_map_pages() for DEBUG_PAGEALLOC case. > > > > The remapping of the pages in safe_copy_page() presumes that it only > > changes protection bits in an existing PTE and so it is safe to ignore > > return value of set_direct_map_{default,invalid}_noflush(). > > > > Still, add a WARN_ON() so that future changes in set_memory APIs will not > > silently break hibernation. > > > > Signed-off-by: Mike Rapoport > > Acked-by: Rafael J. Wysocki > > --- > > include/linux/mm.h | 12 ------------ > > kernel/power/snapshot.c | 30 ++++++++++++++++++++++++++++-- > > 2 files changed, 28 insertions(+), 14 deletions(-) > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 1fc0609056dc..14e397f3752c 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -2927,16 +2927,6 @@ static inline bool debug_pagealloc_enabled_static(void) > > #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP) > > extern void __kernel_map_pages(struct page *page, int numpages, int enable); > > -/* > > - * When called in DEBUG_PAGEALLOC context, the call should most likely be > > - * guarded by debug_pagealloc_enabled() or debug_pagealloc_enabled_static() > > - */ > > -static inline void > > -kernel_map_pages(struct page *page, int numpages, int enable) > > -{ > > - __kernel_map_pages(page, numpages, enable); > > -} > > - > > static inline void debug_pagealloc_map_pages(struct page *page, > > int numpages, int enable) > > { > > @@ -2948,8 +2938,6 @@ static inline void debug_pagealloc_map_pages(struct page *page, > > extern bool kernel_page_present(struct page *page); > > #endif /* CONFIG_HIBERNATION */ > > #else /* CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */ > > -static inline void > > -kernel_map_pages(struct page *page, int numpages, int enable) {} > > static inline void debug_pagealloc_map_pages(struct page *page, > > int numpages, int enable) {} > > #ifdef CONFIG_HIBERNATION > > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c > > index 46b1804c1ddf..054c8cce4236 100644 > > --- a/kernel/power/snapshot.c > > +++ b/kernel/power/snapshot.c > > @@ -76,6 +76,32 @@ static inline void hibernate_restore_protect_page(void *page_address) {} > > static inline void hibernate_restore_unprotect_page(void *page_address) {} > > #endif /* CONFIG_STRICT_KERNEL_RWX && CONFIG_ARCH_HAS_SET_MEMORY */ > > +static inline void hibernate_map_page(struct page *page, int enable) > > +{ > > + if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) { > > + unsigned long addr = (unsigned long)page_address(page); > > + int ret; > > + > > + /* > > + * This should not fail because remapping a page here means > > + * that we only update protection bits in an existing PTE. > > + * It is still worth to have WARN_ON() here if something > > + * changes and this will no longer be the case. > > + */ > > + if (enable) > > + ret = set_direct_map_default_noflush(page); > > + else > > + ret = set_direct_map_invalid_noflush(page); > > + > > + if (WARN_ON(ret)) > > + return; > > People seem to prefer pr_warn() now that production kernels have panic on > warn enabled. It's weird. Weird indeed as the whole point of WARN to yell without causing a crash... I can change to pr_warn though... > > + > > + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); > > + } else { > > + debug_pagealloc_map_pages(page, 1, enable); > > Reviewed-by: David Hildenbrand Thanks! > -- > Thanks, > > David / dhildenb > -- Sincerely yours, Mike.