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=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 2F70CC10F11 for ; Mon, 22 Apr 2019 21:37:56 +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 A5A912075A for ; Mon, 22 Apr 2019 21:37:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5A912075A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44p0L93VshzDqNb for ; Tue, 23 Apr 2019 07:37:53 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=redhat.com (client-ip=209.132.183.28; helo=mx1.redhat.com; envelope-from=jglisse@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (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 44p0JR72DdzDqLd for ; Tue, 23 Apr 2019 07:36:23 +1000 (AEST) 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 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) 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: jack@suse.cz, sergey.senozhatsky.work@gmail.com, peterz@infradead.org, Will Deacon , mhocko@kernel.org, linux-mm@kvack.org, paulus@samba.org, Punit Agrawal , hpa@zytor.com, Michel Lespinasse , Alexei Starovoitov , Andrea Arcangeli , ak@linux.intel.com, Minchan Kim , aneesh.kumar@linux.ibm.com, x86@kernel.org, Matthew Wilcox , Daniel Jordan , Ingo Molnar , David Rientjes , paulmck@linux.vnet.ibm.com, Haiyan Song , npiggin@gmail.com, sj38.park@gmail.com, dave@stgolabs.net, kemi.wang@intel.com, kirill@shutemov.name, Thomas Gleixner , zhong jiang , Ganesh Mahendran , Yang Shi , Mike Rapoport , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Vinayak Menon , vinayak menon , akpm@linux-foundation.org, Tim Chen , haren@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 >