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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 12C7DC43215 for ; Mon, 25 Nov 2019 00:05:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC251206E0 for ; Mon, 25 Nov 2019 00:05:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="m1Cur0PI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727104AbfKYAFV (ORCPT ); Sun, 24 Nov 2019 19:05:21 -0500 Received: from hqemgate14.nvidia.com ([216.228.121.143]:10959 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726803AbfKYAFU (ORCPT ); Sun, 24 Nov 2019 19:05:20 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Sun, 24 Nov 2019 16:05:21 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Sun, 24 Nov 2019 16:05:18 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Sun, 24 Nov 2019 16:05:18 -0800 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 25 Nov 2019 00:05:17 +0000 Subject: Re: [PATCH v7 07/24] IB/umem: use get_user_pages_fast() to pin DMA pages To: Leon Romanovsky , Jason Gunthorpe CC: Christoph Hellwig , Andrew Morton , Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jens Axboe , Jonathan Corbet , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML References: <20191121071354.456618-1-jhubbard@nvidia.com> <20191121071354.456618-8-jhubbard@nvidia.com> <20191121080746.GC30991@infradead.org> <20191121143643.GC7448@ziepe.ca> <20191124100724.GH136476@unreal> From: John Hubbard X-Nvconfidentiality: public Message-ID: Date: Sun, 24 Nov 2019 16:05:16 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191124100724.GH136476@unreal> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1574640321; bh=LD2/8CChGaLRqwmCQwChsDcrQNaYP+P0SNIyxfam1DE=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=m1Cur0PIy3/gI1zO5nV/8By6N43vWGtuN3DH4UA+V5btajIgmajkoqysSp76dAM7w IjD++zms/7U0GGOl8H1gvnNrWhHWhVeKks5+FnTeGfmeFzSgL9stvUxQHdGHcRSpYo R3DhHzHen8GFnhgTTJui8NWTHWe8ATpW8fDVP5C1LALRj6SKkngA39wPoPH2DIIK+J +UKod6U+vX3PK6ephcVmHTxq0zUWIVkMBfEaq7/xc7P3ltk2DNSjaGhY5cT49gyP2u jH1s4PE7IC41UINf5rjHYQtI6U45lVsEN7ZT+BkTbP2xn4k8PFfNWniDCzwNggU9zg iu5V3RFGAA2WA== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 11/24/19 2:07 AM, Leon Romanovsky wrote: > On Thu, Nov 21, 2019 at 10:36:43AM -0400, Jason Gunthorpe wrote: >> On Thu, Nov 21, 2019 at 12:07:46AM -0800, Christoph Hellwig wrote: >>> On Wed, Nov 20, 2019 at 11:13:37PM -0800, John Hubbard wrote: >>>> And get rid of the mmap_sem calls, as part of that. Note >>>> that get_user_pages_fast() will, if necessary, fall back to >>>> __gup_longterm_unlocked(), which takes the mmap_sem as needed. >>>> >>>> Reviewed-by: Jan Kara >>>> Reviewed-by: Jason Gunthorpe >>>> Reviewed-by: Ira Weiny >>>> Signed-off-by: John Hubbard >>> >>> Looks fine, >>> >>> Reviewed-by: Christoph Hellwig >>> >>> Jason, can you queue this up for 5.5 to reduce this patch stack a bit? >> >> Yes, I said I'd do this in an earlier revision. Now that it is clear this >> won't go through Andrew's tree, applied to rdma for-next > > Jason, > > This patch broke RDMA completely. > Change from get_user_pages() to get_user_pages_fast() causes to endless > amount of splats due to combination of the following code: > > 189 struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr, > 190 size_t size, int access) > ... > 263 if (!umem->writable) > 264 gup_flags |= FOLL_FORCE; > 265 > > and > > 2398 int get_user_pages_fast(unsigned long start, int nr_pages, > 2399 unsigned int gup_flags, struct page **pages) > 2400 { > 2401 unsigned long addr, len, end; > 2402 int nr = 0, ret = 0; > 2403 > 2404 if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM))) > 2405 return -EINVAL; > Hi Leon, I looked into this, and I believe that the problem is in gup.c. There appears to have been an oversight, in commit 817be129e6f2 ("mm: validate get_user_pages_fast flags"), in filtering out FOLL_FORCE. There is nothing in the _fast() implementation that requires that we avoid writing to the pages. So I intend, to post a two-patch series that includes this fix, first, but maybe this means that it should go in via -mm. I'm not sure what's the best tree. diff --git a/mm/gup.c b/mm/gup.c index 8f236a335ae9..745b4036cdfd 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2401,7 +2401,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, unsigned long addr, len, end; int nr = 0, ret = 0; - if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM))) + if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | + FOLL_FORCE))) return -EINVAL; start = untagged_addr(start) & PAGE_MASK; thanks, -- John Hubbard NVIDIA > > [ 72.623266] ------------[ cut here ]------------ > [ 72.624143] WARNING: CPU: 1 PID: 2557 at mm/gup.c:2404 get_user_pages_fast+0x115/0x180 > [ 72.625426] Modules linked in: xt_MASQUERADE iptable_nat nf_nat > br_netfilter overlay ib_srp scsi_transport_srp rpcrdma rdma_ucm > ib_iser libiscsi scsi_transport_iscsi rdma_cm ib_umad iw_cm ib_ipoib > ib_cm mlx5_ib ib_uverbs ib_core mlx5_core mlxfw ptp pps_core > [ 72.629024] CPU: 1 PID: 2557 Comm: python3 Not tainted 5.4.0-rc5-J6120-Geeb831ec5b80 #1 > [ 72.630435] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 > [ 72.631973] RIP: 0010:get_user_pages_fast+0x115/0x180 > [ 72.632873] Code: 8d 0c 10 85 c0 89 d0 0f 49 c1 eb 97 fa 4c 8d > 44 24 0c 4c 89 e9 44 89 e2 48 89 df e8 25 dd ff ff fb 8b 44 24 0c > e9 75 ff ff ff <0f> 0b b8 ea ff ff ff e9 6d ff ff ff 65 4c 8b 2c > 25 00 5d 01 00 49 > [ 72.635967] RSP: 0018:ffffc90000edf930 EFLAGS: 00010202 > [ 72.636896] RAX: 0000000000000000 RBX: 00007f931c392000 RCX: ffff8883f4909000 > [ 72.638117] RDX: 0000000000010011 RSI: 0000000000000001 RDI: 00007f931c392000 > [ 72.639353] RBP: 00007f931c392000 R08: 0000000000000020 R09: ffff8883f4909000 > [ 72.640602] R10: 0000000000000000 R11: ffff8884068d6760 R12: ffff888409e45ba0 > [ 72.641858] R13: ffff8884068d6760 R14: 0000160000000000 R15: ffff8883f4909000 > [ 72.643115] FS: 00007f9323754700(0000) GS:ffff88842fa80000(0000) knlGS:0000000000000000 > [ 72.644586] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 72.645628] CR2: 00007f931c3ca000 CR3: 00000003f83d6006 CR4: 00000000007606a0 > [ 72.646875] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 72.648120] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 72.649374] PKRU: 55555554 > [ 72.649935] Call Trace: > [ 72.650477] ib_umem_get+0x298/0x550 [ib_uverbs] > [ 72.651347] mlx5_ib_db_map_user+0xad/0x130 [mlx5_ib] > [ 72.652279] mlx5_ib_create_cq+0x1e8/0xaa0 [mlx5_ib] > [ 72.653207] create_cq+0x1c8/0x2d0 [ib_uverbs] > [ 72.654050] ib_uverbs_create_cq+0x70/0xa0 [ib_uverbs] > [ 72.654988] ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0xc2/0xf0 [ib_uverbs] > [ 72.656331] ib_uverbs_cmd_verbs.isra.6+0x5be/0xbe0 [ib_uverbs] > [ 72.657398] ? uverbs_disassociate_api+0xd0/0xd0 [ib_uverbs] > [ 72.658423] ? kvm_clock_get_cycles+0xd/0x10 > [ 72.659229] ? kmem_cache_alloc+0x176/0x1c0 > [ 72.660025] ? filemap_map_pages+0x18c/0x350 > [ 72.660838] ib_uverbs_ioctl+0xc0/0x120 [ib_uverbs] > [ 72.661756] do_vfs_ioctl+0xa1/0x610 > [ 72.662458] ksys_ioctl+0x70/0x80 > [ 72.663119] __x64_sys_ioctl+0x16/0x20 > [ 72.663850] do_syscall_64+0x42/0x110 > [ 72.664562] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 72.665492] RIP: 0033:0x7f9332958267 > [ 72.666185] Code: b3 66 90 48 > 8b 05 19 3c 2c 00 64 c7 00 26 00 > 00 00 48 c7 c0 ff ff ff ff c3 66 > 2e 0f 1f 84 00 00 00 00 00 b8 10 > 00 00 00 0f 05 <48> 3d 01 f0 ff > ff 73 01 c3 48 8b 0d e9 3b 2c 00 > f7 d8 64 89 01 48 > [ 72.669347] RSP: 002b:00007f9323751928 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > [ 72.670706] RAX: ffffffffffffffda RBX: 00007f93237519b8 RCX: 00007f9332958267 > [ 72.671937] RDX: 00007f93237519a0 RSI: 00000000c0181b01 RDI: 0000000000000008 > [ 72.673176] RBP: 00007f9323751980 R08: 0000000000000005 R09: 00007f931c3ffef0 > [ 72.674415] R10: 0000000000001000 R11: 0000000000000246 R12: 00007f931c400030 > [ 72.675653] R13: 00007f9323751980 R14: 00007f9323751ea8 R15: 00000000000000ff > [ 72.676885] ---[ end trace 033465440517865c ]--- > >> >> Thanks, >> Jason >>