From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 78A406B025F for ; Mon, 14 Aug 2017 00:58:12 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id s14so115184555pgs.4 for ; Sun, 13 Aug 2017 21:58:12 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id l61si4136544plb.86.2017.08.13.21.58.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 13 Aug 2017 21:58:11 -0700 (PDT) Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7E4rrav075505 for ; Mon, 14 Aug 2017 00:58:10 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0a-001b2d01.pphosted.com with ESMTP id 2cb2m5nvd9-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 14 Aug 2017 00:58:09 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 14 Aug 2017 05:58:07 +0100 Date: Mon, 14 Aug 2017 07:58:03 +0300 From: Mike Rapoport Subject: Re: [RFC PATCH 0/5] userfaultfd: non-cooperative: syncronous events References: <1494930962-3318-1-git-send-email-rppt@linux.vnet.ibm.com> <20170627133952.GA25343@rapoport-lnx> <011e01d312a8$3c97e6b0$b5c7b410$@colorado.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <011e01d312a8$3c97e6b0$b5c7b410$@colorado.edu> Message-Id: <20170814045802.GA18287@rapoport-lnx> Sender: owner-linux-mm@kvack.org List-ID: To: Blake Caldwell Cc: 'Pavel Emelyanov' , 'linux-mm' , 'Andrea Arcangeli' Hi, On Fri, Aug 11, 2017 at 09:46:29AM -0400, Blake Caldwell wrote: > > On Tue, May 16, 2017 at 01:35:57PM +0300, Mike Rapoport wrote: > > > Hi, > > > > Any comments on this? > > Shall I repost without the "RFC" prefix? > > > I have a use case for this feature exactly like what you have described. The > process should be suspended until the event has been handled. I would like > to test this if there is a rebased patchset out there somewhere? I'm using > 4.13.0_rc3 from > https://kernel.googlesource.com/pub/scm/linux/kernel/git/andrea/aa.git > > I wasn't able to apply the patches without heavy modification (mostly patch > 3/5). I don't have a version rebased on Andrea's tree, sorry. > Thanks for the work on this. > > > These patches add ability to generate userfaultfd events so that thier > > > processing will be synchronized with the non-cooperative thread that > > > caused the event. > > > > > > In the non-cooperative case userfaultfd resumes execution of the > > > thread that caused an event when the notification is read() by the uffd > > monitor. > > > In some cases, like, for example, madvise(MADV_REMOVE), it might be > > > desirable to keep the thread that caused the event suspended until the > > > uffd monitor had the event handled. > > > > > > The first two patches just shuffle the code a bit to make subsequent > > > changes easier. > > > The patches 3 and 4 create some unification in the way the threads are > > > queued into waitqueues either after page fault or after a > > > non-cooperative event. > > > The fifth patch extends the userfaultfd API with an implementation of > > > UFFD_EVENT_REMOVE_SYNC that allows to keep the thread that triggered > > > UFFD_EVENT_REMOVE until the uffd monitor would not wake it explicitly. > > > > > > Mike Rapoport (5): > > > userfaultfd: introduce userfault_init_waitqueue helper > > > userfaultfd: introduce userfaultfd_should_wait helper > > > userfaultfd: non-cooperative: generalize wake key structure > > > userfaultfd: non-cooperative: use fault_pending_wqh for all events > > > userfaultfd: non-cooperative: allow synchronous EVENT_REMOVE > > > > > > fs/userfaultfd.c | 205 > ++++++++++++++++++++++++--------------- > > > include/uapi/linux/userfaultfd.h | 11 +++ > > > 2 files changed, 136 insertions(+), 80 deletions(-) > > > > > > -- > > > 2.7.4 > > > > > > > -- > > To unsubscribe, send a message with 'unsubscribe linux-mm' in > > the body to majordomo@kvack.org. For more info on Linux MM, > > see: http://www.linux-mm.org/ . > > Don't email: email@kvack.org > -- Sincerely yours, Mike. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org