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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 76C04C43334 for ; Mon, 3 Sep 2018 08:35:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3040F20843 for ; Mon, 3 Sep 2018 08:35:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="oHUFv0BO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3040F20843 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727280AbeICMya (ORCPT ); Mon, 3 Sep 2018 08:54:30 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34678 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725990AbeICMy3 (ORCPT ); Mon, 3 Sep 2018 08:54:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=8lQVV6BgBneRbh6weoRWgGuOx3KFs5swKmFPHzGdnb4=; b=oHUFv0BOqfvz/N1h/4OTpFE2q VZvCUjsfSfTsYwqovIYX83UfXtKIuFn4o70FwEv4RjZo+LE+SJUknwlH7FLSGX8JaO/tDVq0UU3L1 L3VpFo8UAs92ChMfJagPG/6O4aHri7tpxq4ynqxca86WLRMTeT9s9dHJ47wEqTo7thgESll5Hpmni 60fVbLzOxfEphZp7FA9z4raLAjJyX+bAbIOJ34c9r3wtBeUWQsSlqODpS1fk5j2mMVSChpEQL6e0m FKrBb/LcKILFcPxGWOV+TEcJ03dB2yI60Yk8eAHqHIY7TR1gf85aAsJ5vpHiF/70Bwg6n9G69bdJG xFlwOc3Tg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fwkK5-0006az-5g; Mon, 03 Sep 2018 08:35:01 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D7B22205F8650; Mon, 3 Sep 2018 10:34:59 +0200 (CEST) Date: Mon, 3 Sep 2018 10:34:59 +0200 From: Peter Zijlstra To: Sai Praneeth Prakhya Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, ricardo.neri@intel.com, matt@codeblueprint.co.uk, Lee Chun-Yi , Al Stone , Borislav Petkov , Ingo Molnar , Andy Lutomirski , Bhupesh Sharma , Ard Biesheuvel , Thomas Gleixner Subject: Re: [PATCH V2 5/6] x86/mm: If in_atomic(), allocate pages without sleeping Message-ID: <20180903083459.GT24124@hirez.programming.kicks-ass.net> References: <1535881594-25469-1-git-send-email-sai.praneeth.prakhya@intel.com> <1535881594-25469-6-git-send-email-sai.praneeth.prakhya@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1535881594-25469-6-git-send-email-sai.praneeth.prakhya@intel.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 02, 2018 at 02:46:33AM -0700, Sai Praneeth Prakhya wrote: > From: Sai Praneeth > > A page fault occurs when any EFI Runtime Service tries to reference a > memory region which it shouldn't. If the illegally accessed region > is EFI_BOOT_SERVICES_, the efi specific page fault handler > fixes it up by dynamically creating VA->PA mappings using > efi_map_region(). > > Originally, efi_map_region() and hence the functionality of creating > mappings for efi regions was intended to be used *only* during boot time > (please note __init modifier) and hence when called during runtime (i.e. > from efi page fault handler), the page allocators complain. Calling > efi_map_region() during runtime complains because "gfp_allowed_mask" > value changes from boot time to runtime (GFP_BOOT_MASK to > __GFP_BITS_MASK). During boot, even though efi_map_region() calls > alloc__page with GFP_KERNEL, the page allocator doesn't > complain because "__GFP_RECLAIM" flag is cleared by "gfp_allowed_mask", > but during runtime it isn't cleared and hence prints below stack trace. > > BUG: sleeping function called from invalid context at mm/page_alloc.c:4320 > get_zeroed_page+0x12/0x40 > alloc_pmd_page+0x13/0x50 > populate_pmd+0xc0/0x2e0 > __cpa_process_fault+0x2e1/0x5d0 > __change_page_attr_set_clr+0x7c3/0xcd0 > kernel_map_pages_in_pgd+0x8c/0x160 > __map_region+0x3c/0x60 > efi_map_region+0x83/0xd0 > efi_illegal_accesses_fixup+0x1ca/0x1e0 > no_context+0x112/0x390 > __do_page_fault+0xc7/0x4f0 > Fix the above warning by conditionally changing the allocation from > GFP_KERNEL to GFP_ATOMIC, so that efi page fault handler could use > efi_map_region() during runtime. This change shouldn't effect any other > generic page allocations because this allocation is used only by efi > functions [1]. > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 3bded76e8d5c..1b28a333c8ce 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -926,7 +926,13 @@ static void unmap_pud_range(p4d_t *p4d, unsigned long start, unsigned long end) > > static int alloc_pte_page(pmd_t *pmd) > { > - pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL); > + pte_t *pte; > + > + if (in_atomic()) > + pte = (pte_t *)get_zeroed_page(GFP_ATOMIC); > + else > + pte = (pte_t *)get_zeroed_page(GFP_KERNEL); > + > if (!pte) > return -1; > This looks like tinkering to me..