From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Date: Thu, 14 Feb 2019 06:00:06 +0000 Subject: Re: [PATCH 0/5] use pinned_vm instead of locked_vm to account pinned pages Message-Id: <20190214060006.GE24692@ziepe.ca> List-Id: References: <20190211224437.25267-1-daniel.m.jordan@oracle.com> <20190211225447.GN24692@ziepe.ca> <20190214015314.GB1151@iweiny-DESK2.sc.intel.com> In-Reply-To: <20190214015314.GB1151@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ira Weiny Cc: Daniel Jordan , akpm@linux-foundation.org, dave@stgolabs.net, jack@suse.cz, cl@linux.com, linux-mm@kvack.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, alex.williamson@redhat.com, paulus@ozlabs.org, benh@kernel.crashing.org, mpe@ellerman.id.au, hao.wu@intel.com, atull@kernel.org, mdf@kernel.org, aik@ozlabs.ru On Wed, Feb 13, 2019 at 05:53:14PM -0800, Ira Weiny wrote: > On Mon, Feb 11, 2019 at 03:54:47PM -0700, Jason Gunthorpe wrote: > > On Mon, Feb 11, 2019 at 05:44:32PM -0500, Daniel Jordan wrote: > > > > > All five of these places, and probably some of Davidlohr's conversions, > > > probably want to be collapsed into a common helper in the core mm for > > > accounting pinned pages. I tried, and there are several details that > > > likely need discussion, so this can be done as a follow-on. > > > > I've wondered the same.. > > I'm really thinking this would be a nice way to ensure it gets cleaned up and > does not happen again. > > Also, by moving it to the core we could better manage any user visible changes. > > From a high level, pinned is a subset of locked so it seems like we need a 2 > sets of helpers. > > try_increment_locked_vm(...) > decrement_locked_vm(...) > > try_increment_pinned_vm(...) > decrement_pinned_vm(...) > > Where try_increment_pinned_vm() also increments locked_vm... Of course this > may end up reverting the improvement of Davidlohr Bueso's atomic work... :-( > > Furthermore it would seem better (although I don't know if at all possible) if > this were accounted for in core calls which tracked them based on how the pages > are being used so that drivers can't call try_increment_locked_vm() and then > pin the pages... Thus getting the account wrong vs what actually happened. > > And then in the end we can go back to locked_vm being the value checked against > RLIMIT_MEMLOCK. Someone would need to understand the bug that was fixed by splitting them. I think it had to do with double accounting pinned and mlocked pages and thus delivering a lower than expected limit to userspace. vfio has this bug, RDMA does not. RDMA has a bug where it can overallocate locked memory, vfio doesn't. Really unclear how to fix this. The pinned/locked split with two buckets may be the right way. Jason From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Wed, 13 Feb 2019 23:00:06 -0700 From: Jason Gunthorpe Subject: Re: [PATCH 0/5] use pinned_vm instead of locked_vm to account pinned pages Message-ID: <20190214060006.GE24692@ziepe.ca> References: <20190211224437.25267-1-daniel.m.jordan@oracle.com> <20190211225447.GN24692@ziepe.ca> <20190214015314.GB1151@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190214015314.GB1151@iweiny-DESK2.sc.intel.com> To: Ira Weiny Cc: Daniel Jordan , akpm@linux-foundation.org, dave@stgolabs.net, jack@suse.cz, cl@linux.com, linux-mm@kvack.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, alex.williamson@redhat.com, paulus@ozlabs.org, benh@kernel.crashing.org, mpe@ellerman.id.au, hao.wu@intel.com, atull@kernel.org, mdf@kernel.org, aik@ozlabs.ru List-ID: On Wed, Feb 13, 2019 at 05:53:14PM -0800, Ira Weiny wrote: > On Mon, Feb 11, 2019 at 03:54:47PM -0700, Jason Gunthorpe wrote: > > On Mon, Feb 11, 2019 at 05:44:32PM -0500, Daniel Jordan wrote: > > > > > All five of these places, and probably some of Davidlohr's conversions, > > > probably want to be collapsed into a common helper in the core mm for > > > accounting pinned pages. I tried, and there are several details that > > > likely need discussion, so this can be done as a follow-on. > > > > I've wondered the same.. > > I'm really thinking this would be a nice way to ensure it gets cleaned up and > does not happen again. > > Also, by moving it to the core we could better manage any user visible changes. > > From a high level, pinned is a subset of locked so it seems like we need a 2 > sets of helpers. > > try_increment_locked_vm(...) > decrement_locked_vm(...) > > try_increment_pinned_vm(...) > decrement_pinned_vm(...) > > Where try_increment_pinned_vm() also increments locked_vm... Of course this > may end up reverting the improvement of Davidlohr Bueso's atomic work... :-( > > Furthermore it would seem better (although I don't know if at all possible) if > this were accounted for in core calls which tracked them based on how the pages > are being used so that drivers can't call try_increment_locked_vm() and then > pin the pages... Thus getting the account wrong vs what actually happened. > > And then in the end we can go back to locked_vm being the value checked against > RLIMIT_MEMLOCK. Someone would need to understand the bug that was fixed by splitting them. I think it had to do with double accounting pinned and mlocked pages and thus delivering a lower than expected limit to userspace. vfio has this bug, RDMA does not. RDMA has a bug where it can overallocate locked memory, vfio doesn't. Really unclear how to fix this. The pinned/locked split with two buckets may be the right way. Jason 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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 9A7FBC43381 for ; Thu, 14 Feb 2019 06:02:03 +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 C04F921934 for ; Thu, 14 Feb 2019 06:02:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="AqFGGKQk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C04F921934 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca 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 440QlD26yrzDqW7 for ; Thu, 14 Feb 2019 17:02:00 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=ziepe.ca (client-ip=2607:f8b0:4864:20::543; helo=mail-pg1-x543.google.com; envelope-from=jgg@ziepe.ca; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ziepe.ca header.i=@ziepe.ca header.b="AqFGGKQk"; dkim-atps=neutral Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) (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 440Qj72yWfzDqTv for ; Thu, 14 Feb 2019 17:00:10 +1100 (AEDT) Received: by mail-pg1-x543.google.com with SMTP id y1so2458333pgk.11 for ; Wed, 13 Feb 2019 22:00:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=EyhZ0LXI8S6DO+1lKPJ+3xCo7Hi2M9DApl/OXP8GRG0=; b=AqFGGKQkWIE4m9oWUPQKPfYDWffEV3DD3kw2gte/hIVc+ZOI2ALww287MyZktoOcDi CbpDfqNDDxjQTYKo+HSL1jPCcxgIu0tlHCqsVDa+M5KY9ZBsLFTmv/t2wqc5kisOEAq3 Ey9IsWcwZPCXnG/nVFmz7GUhhGKdm8IWeTP2Dk0HwbmuU3cqx7K5BZzuoEE5qUenFwFw FhXuEgKL+2MrnrRuMG0A1nR+NYB/69dpYPvc7V/phtqqydIA5J2EkPID7AxDk9lsLjAP NbaOeXfbMwnJ+uPtI2ATX/eErFA+0vBz71ipAT/cQzRY+HNlZcQmNhta5uk0wuPGbr4p 3GKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=EyhZ0LXI8S6DO+1lKPJ+3xCo7Hi2M9DApl/OXP8GRG0=; b=rqN9ZUxhcCyXhYnlw/jKdcjMttov6hlfTfsWNUFhMTm19FZeDmmEHiszYKOERHSq08 +5YjL7zIBwD+gj8h/a2KRAL2j+YJbpDacR26gpJvD0V/zVKL39nCE9Wi581KUXCtV+bX mMWUfxWHXigc4Hgpa1goytjH7gzH2Su2+xbQ26Gf59Fk+gjrcyPd6nbfOd1RIAdUJKJB xdo5OmODVRvG6dL4A+X6IMcMEQsA7nqDf0o+ijPzXEPgaVG3v/jkvEKcP1oCbWWRinlT VJiS+mOhD6JwdVZY1m4tyFCkLvvja5xUfafiZIIU4fNvYBku1beRMQHqc5B2WC/WBow8 9p4g== X-Gm-Message-State: AHQUAubyeooaM1fH+SZNOjgfZ0indYsOIOMyMmDyfjz7NQp5AXvErBOR +i34AeL9bK2naODLjUlz9TyGeA== X-Google-Smtp-Source: AHgI3IZsTuAr/2agKNUI6fHNmik1DYYjhaWBR5rn+7baCxky03ZS5RyeSxDZdNqDP/QzwRlb2m6TAA== X-Received: by 2002:a62:9f1a:: with SMTP id g26mr2297647pfe.123.1550124008008; Wed, 13 Feb 2019 22:00:08 -0800 (PST) Received: from ziepe.ca (S010614cc2056d97f.ed.shawcable.net. [174.3.196.123]) by smtp.gmail.com with ESMTPSA id z127sm2288820pfb.80.2019.02.13.22.00.07 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 13 Feb 2019 22:00:07 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1guA46-00040P-Jk; Wed, 13 Feb 2019 23:00:06 -0700 Date: Wed, 13 Feb 2019 23:00:06 -0700 From: Jason Gunthorpe To: Ira Weiny Subject: Re: [PATCH 0/5] use pinned_vm instead of locked_vm to account pinned pages Message-ID: <20190214060006.GE24692@ziepe.ca> References: <20190211224437.25267-1-daniel.m.jordan@oracle.com> <20190211225447.GN24692@ziepe.ca> <20190214015314.GB1151@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190214015314.GB1151@iweiny-DESK2.sc.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) 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: dave@stgolabs.net, jack@suse.cz, kvm@vger.kernel.org, atull@kernel.org, aik@ozlabs.ru, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, Daniel Jordan , linux-mm@kvack.org, alex.williamson@redhat.com, mdf@kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, cl@linux.com, hao.wu@intel.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Feb 13, 2019 at 05:53:14PM -0800, Ira Weiny wrote: > On Mon, Feb 11, 2019 at 03:54:47PM -0700, Jason Gunthorpe wrote: > > On Mon, Feb 11, 2019 at 05:44:32PM -0500, Daniel Jordan wrote: > > > > > All five of these places, and probably some of Davidlohr's conversions, > > > probably want to be collapsed into a common helper in the core mm for > > > accounting pinned pages. I tried, and there are several details that > > > likely need discussion, so this can be done as a follow-on. > > > > I've wondered the same.. > > I'm really thinking this would be a nice way to ensure it gets cleaned up and > does not happen again. > > Also, by moving it to the core we could better manage any user visible changes. > > From a high level, pinned is a subset of locked so it seems like we need a 2 > sets of helpers. > > try_increment_locked_vm(...) > decrement_locked_vm(...) > > try_increment_pinned_vm(...) > decrement_pinned_vm(...) > > Where try_increment_pinned_vm() also increments locked_vm... Of course this > may end up reverting the improvement of Davidlohr Bueso's atomic work... :-( > > Furthermore it would seem better (although I don't know if at all possible) if > this were accounted for in core calls which tracked them based on how the pages > are being used so that drivers can't call try_increment_locked_vm() and then > pin the pages... Thus getting the account wrong vs what actually happened. > > And then in the end we can go back to locked_vm being the value checked against > RLIMIT_MEMLOCK. Someone would need to understand the bug that was fixed by splitting them. I think it had to do with double accounting pinned and mlocked pages and thus delivering a lower than expected limit to userspace. vfio has this bug, RDMA does not. RDMA has a bug where it can overallocate locked memory, vfio doesn't. Really unclear how to fix this. The pinned/locked split with two buckets may be the right way. Jason