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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,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 9E3A1C10F11 for ; Mon, 22 Apr 2019 21:36:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77D3220811 for ; Mon, 22 Apr 2019 21:36:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730118AbfDVVgW (ORCPT ); Mon, 22 Apr 2019 17:36:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34166 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727386AbfDVVgW (ORCPT ); Mon, 22 Apr 2019 17:36:22 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5F1213092650; Mon, 22 Apr 2019 21:36:21 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 94B225D9D4; Mon, 22 Apr 2019 21:36:13 +0000 (UTC) Date: Mon, 22 Apr 2019 17:36:11 -0400 From: Jerome Glisse To: Laurent Dufour Cc: akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , aneesh.kumar@linux.ibm.com, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , sergey.senozhatsky.work@gmail.com, Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, Daniel Jordan , David Rientjes , Ganesh Mahendran , Minchan Kim , Punit Agrawal , vinayak menon , Yang Shi , zhong jiang , Haiyan Song , Balbir Singh , sj38.park@gmail.com, Michel Lespinasse , Mike Rapoport , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, npiggin@gmail.com, paulmck@linux.vnet.ibm.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org, Vinayak Menon Subject: Re: [PATCH v12 23/31] mm: don't do swap readahead during speculative page fault Message-ID: <20190422213611.GN14666@redhat.com> References: <20190416134522.17540-1-ldufour@linux.ibm.com> <20190416134522.17540-24-ldufour@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190416134522.17540-24-ldufour@linux.ibm.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 22 Apr 2019 21:36:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 16, 2019 at 03:45:14PM +0200, Laurent Dufour wrote: > Vinayak Menon faced a panic because one thread was page faulting a page in > swap, while another one was mprotecting a part of the VMA leading to a VMA > split. > This raise a panic in swap_vma_readahead() because the VMA's boundaries > were not more matching the faulting address. > > To avoid this, if the page is not found in the swap, the speculative page > fault is aborted to retry a regular page fault. > > Reported-by: Vinayak Menon > Signed-off-by: Laurent Dufour Reviewed-by: Jérôme Glisse Note that you should also skip non swap entry in do_swap_page() when doing speculative page fault at very least you need to is_device_private_entry() case. But this should either be part of patch 22 or another patch to fix swap case. > --- > mm/memory.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/mm/memory.c b/mm/memory.c > index 6e6bf61c0e5c..1991da97e2db 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2900,6 +2900,17 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > lru_cache_add_anon(page); > swap_readpage(page, true); > } > + } else if (vmf->flags & FAULT_FLAG_SPECULATIVE) { > + /* > + * Don't try readahead during a speculative page fault > + * as the VMA's boundaries may change in our back. > + * If the page is not in the swap cache and synchronous > + * read is disabled, fall back to the regular page > + * fault mechanism. > + */ > + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); > + ret = VM_FAULT_RETRY; > + goto out; > } else { > page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, > vmf); > -- > 2.21.0 >