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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFB24ECAAA1 for ; Tue, 6 Sep 2022 19:40:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229947AbiIFTkJ (ORCPT ); Tue, 6 Sep 2022 15:40:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229883AbiIFTj7 (ORCPT ); Tue, 6 Sep 2022 15:39:59 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01FDA491F6 for ; Tue, 6 Sep 2022 12:39:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662493196; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ipDmQ48fSdnKUDgmzFqHXYya44lh/1wuhiABbNwvM7Y=; b=ck9ijTxR/Q73O0X3pJmd4vxIxuwEJpBkYFM5b0wEQxI7dnuE98GfACBeZdMDy5Grd/VEdJ K14QOSu4yJgx8iLBwMaOwyekUtQZfbuLbkiBfYobOJQP+DQIeZ1l3tGS6Ei/8kAWo0Ezjr VNL2x2JgHynC+fP4CMvNbz7SdMjw9jU= Received: from mail-qt1-f200.google.com (mail-qt1-f200.google.com [209.85.160.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-178-E2LB8JCcMzicL81fqN3SeA-1; Tue, 06 Sep 2022 15:39:55 -0400 X-MC-Unique: E2LB8JCcMzicL81fqN3SeA-1 Received: by mail-qt1-f200.google.com with SMTP id b10-20020a05622a020a00b003437e336ca7so9961662qtx.16 for ; Tue, 06 Sep 2022 12:39:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=ipDmQ48fSdnKUDgmzFqHXYya44lh/1wuhiABbNwvM7Y=; b=fBQlHXNc2O+2KaiZRkyl/hAMxGvMSh9nywXi0o00rbYwkyUbbEI1oQEK0FyIwWFfC/ WuWzZM/tcycZjEePolVjfIz7XHlNyGBmdnCMtAbhSAPAUcwpy/GusDSokSVlqDrdaFBy U6pXatkcQG/y6IJGshWYRvbE3uWOko8FFWDpJ/CYIwn+BUBWNarorrrEh4PzOi9sXYIX JxtWEOSSblBVEEDmvlGfXo335yFvR44wZIFHnZvKGtxH1XrIUv0+siWuj+50LQVoN+mZ q+WkiBru4fkvdH6ySJyPP4zM+c3j/NpD6Zb/0ysSbAws+hd8JqT88y7xuFMwYrp6rJBp K6iw== X-Gm-Message-State: ACgBeo1hZ7+i3EPSASfUagcBr1RDN0DaEbyXBkWlBCsEXVWWi/x63u4c y5hAxIygHTEbnfWzBEXQnk5CPK5m9C/ihqOpbqFujlCzlnikh6XnKcSBd9fdsMkJNpJHHBxKWvm Ff/ylpERaXjOJ7lK7dj0ZIZIA X-Received: by 2002:a05:620a:2591:b0:6c9:cc85:87e3 with SMTP id x17-20020a05620a259100b006c9cc8587e3mr165292qko.577.1662493195306; Tue, 06 Sep 2022 12:39:55 -0700 (PDT) X-Google-Smtp-Source: AA6agR7ttYQWiRMBv+iRAUF0TI1KrYDEUj4oUMahpKt92mQKBQU68PcCAvUwsnwEAqRUP4s0fa6Zng== X-Received: by 2002:a05:620a:2591:b0:6c9:cc85:87e3 with SMTP id x17-20020a05620a259100b006c9cc8587e3mr165268qko.577.1662493195065; Tue, 06 Sep 2022 12:39:55 -0700 (PDT) Received: from xz-m1.local (bras-base-aurron9127w-grc-35-70-27-3-10.dsl.bell.ca. [70.27.3.10]) by smtp.gmail.com with ESMTPSA id bk22-20020a05620a1a1600b006b9c9b7db8bsm12167528qkb.82.2022.09.06.12.39.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Sep 2022 12:39:54 -0700 (PDT) Date: Tue, 6 Sep 2022 15:39:51 -0400 From: Peter Xu To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH RESEND 19/28] mm: disallow do_swap_page to handle page faults under VMA lock Message-ID: References: <20220901173516.702122-1-surenb@google.com> <20220901173516.702122-20-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220901173516.702122-20-surenb@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 01, 2022 at 10:35:07AM -0700, Suren Baghdasaryan wrote: > Due to the possibility of do_swap_page dropping mmap_lock, abort fault > handling under VMA lock and retry holding mmap_lock. This can be handled > more gracefully in the future. > > Signed-off-by: Suren Baghdasaryan > --- > mm/memory.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/memory.c b/mm/memory.c > index 9ac9944e8c62..29d2f49f922a 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3738,6 +3738,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > vm_fault_t ret = 0; > void *shadow = NULL; > > + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { > + ret = VM_FAULT_RETRY; > + goto out; > + } > + May want to fail early similarly for handle_userfault() too for similar reason. Thanks, -- Peter Xu