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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,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 23FC9C388F9 for ; Sat, 31 Oct 2020 02:55:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8015022249 for ; Sat, 31 Oct 2020 02:55:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="AtOxaAfN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8015022249 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ADC1D6B0036; Fri, 30 Oct 2020 22:55:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A8B1C6B005C; Fri, 30 Oct 2020 22:55:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 952BA6B005D; Fri, 30 Oct 2020 22:55:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0114.hostedemail.com [216.40.44.114]) by kanga.kvack.org (Postfix) with ESMTP id 663F26B0036 for ; Fri, 30 Oct 2020 22:55:31 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 069A3180AD806 for ; Sat, 31 Oct 2020 02:55:31 +0000 (UTC) X-FDA: 77430704862.18.pen74_2f13d2d2729b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id DA71F100EC664 for ; Sat, 31 Oct 2020 02:55:30 +0000 (UTC) X-HE-Tag: pen74_2f13d2d2729b X-Filterd-Recvd-Size: 9646 Received: from hqnvemgate25.nvidia.com (hqnvemgate25.nvidia.com [216.228.121.64]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Sat, 31 Oct 2020 02:55:29 +0000 (UTC) Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Fri, 30 Oct 2020 19:55:30 -0700 Received: from [10.2.58.85] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sat, 31 Oct 2020 02:55:18 +0000 Subject: Re: [PATCH v5 05/15] mm/frame-vector: Use FOLL_LONGTERM To: Daniel Vetter , DRI Development , LKML CC: , , , , , Daniel Vetter , "Jason Gunthorpe" , Pawel Osciak , Marek Szyprowski , Kyungmin Park , "Tomasz Figa" , Mauro Carvalho Chehab , Andrew Morton , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Dan Williams References: <20201030100815.2269-1-daniel.vetter@ffwll.ch> <20201030100815.2269-6-daniel.vetter@ffwll.ch> From: John Hubbard Message-ID: <446b2d5b-a1a1-a408-f884-f17a04b72c18@nvidia.com> Date: Fri, 30 Oct 2020 19:55:17 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201030100815.2269-6-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1604112930; bh=kIbuOrZMF2YQAWfUPs6gkqYbyNybPPlpG1DHBddVTeI=; h=Subject:To:CC:References:From:Message-ID:Date:User-Agent: MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=AtOxaAfNPVF2Y8gZFgz8BlJTCY2WnS/ll/uZOpZY6ZM3sYeZDX0wsWzg9kbJTYbtL uIT7SI94Nu0DAKox4tjTnJcLN8XQH4afRazJUVETQXmRDSkforw/ZyajpCSjQdhakD V5TkHQG1hyUHjxO5/EziqQ5QU5HsvmsdLhy0c2pJ17Ik4sdOeRb9MDZW7AgVbI6HUp khbiVPlvAQBqPZreVxuJwdPBCd0dFyD9l044fmdbRBxITLNtDeDmPV0I8qXzaQGtcL 05gwU5zD1T2KQ11VFOtz4tXHAh7iSeMGU/Zo8kgIrMlYShlD2P3PVWKbYJ1hjOt5Cc x4G0lu6VoJy1w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/30/20 3:08 AM, Daniel Vetter wrote: > This is used by media/videbuf2 for persistent dma mappings, not just > for a single dma operation and then freed again, so needs > FOLL_LONGTERM. >=20 > Unfortunately current pup_locked doesn't support FOLL_LONGTERM due to > locking issues. Rework the code to pull the pup path out from the > mmap_sem critical section as suggested by Jason. >=20 > By relying entirely on the vma checks in pin_user_pages and follow_pfn There are vma checks in pin_user_pages(), but this patch changes things to call pin_user_pages_fast(). And that does not have the vma checks. More below about this: > (for vm_flags and vma_is_fsdax) we can also streamline the code a lot. >=20 > Signed-off-by: Daniel Vetter > Cc: Jason Gunthorpe > Cc: Pawel Osciak > Cc: Marek Szyprowski > Cc: Kyungmin Park > Cc: Tomasz Figa > Cc: Mauro Carvalho Chehab > Cc: Andrew Morton > Cc: John Hubbard > Cc: J=C3=A9r=C3=B4me Glisse > Cc: Jan Kara > Cc: Dan Williams > Cc: linux-mm@kvack.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-samsung-soc@vger.kernel.org > Cc: linux-media@vger.kernel.org > Signed-off-by: Daniel Vetter > -- > v2: Streamline the code and further simplify the loop checks (Jason) >=20 > v5: Review from Tomasz: > - fix page counting for the follow_pfn case by resetting ret > - drop gup_flags paramater, now unused > --- > .../media/common/videobuf2/videobuf2-memops.c | 3 +- > include/linux/mm.h | 2 +- > mm/frame_vector.c | 53 ++++++------------- > 3 files changed, 19 insertions(+), 39 deletions(-) >=20 > diff --git a/drivers/media/common/videobuf2/videobuf2-memops.c b/drivers/= media/common/videobuf2/videobuf2-memops.c > index 6e9e05153f4e..9dd6c27162f4 100644 > --- a/drivers/media/common/videobuf2/videobuf2-memops.c > +++ b/drivers/media/common/videobuf2/videobuf2-memops.c > @@ -40,7 +40,6 @@ struct frame_vector *vb2_create_framevec(unsigned long = start, > unsigned long first, last; > unsigned long nr; > struct frame_vector *vec; > - unsigned int flags =3D FOLL_FORCE | FOLL_WRITE; > =20 > first =3D start >> PAGE_SHIFT; > last =3D (start + length - 1) >> PAGE_SHIFT; > @@ -48,7 +47,7 @@ struct frame_vector *vb2_create_framevec(unsigned long = start, > vec =3D frame_vector_create(nr); > if (!vec) > return ERR_PTR(-ENOMEM); > - ret =3D get_vaddr_frames(start & PAGE_MASK, nr, flags, vec); > + ret =3D get_vaddr_frames(start & PAGE_MASK, nr, vec); > if (ret < 0) > goto out_destroy; > /* We accept only complete set of PFNs */ > diff --git a/include/linux/mm.h b/include/linux/mm.h > index ef360fe70aaf..d6b8e30dce2e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1765,7 +1765,7 @@ struct frame_vector { > struct frame_vector *frame_vector_create(unsigned int nr_frames); > void frame_vector_destroy(struct frame_vector *vec); > int get_vaddr_frames(unsigned long start, unsigned int nr_pfns, > - unsigned int gup_flags, struct frame_vector *vec); > + struct frame_vector *vec); > void put_vaddr_frames(struct frame_vector *vec); > int frame_vector_to_pages(struct frame_vector *vec); > void frame_vector_to_pfns(struct frame_vector *vec); > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > index 10f82d5643b6..f8c34b895c76 100644 > --- a/mm/frame_vector.c > +++ b/mm/frame_vector.c > @@ -32,13 +32,12 @@ > * This function takes care of grabbing mmap_lock as necessary. > */ > int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > - unsigned int gup_flags, struct frame_vector *vec) > + struct frame_vector *vec) > { > struct mm_struct *mm =3D current->mm; > struct vm_area_struct *vma; > int ret =3D 0; > int err; > - int locked; > =20 > if (nr_frames =3D=3D 0) > return 0; > @@ -48,40 +47,26 @@ int get_vaddr_frames(unsigned long start, unsigned in= t nr_frames, > =20 > start =3D untagged_addr(start); > =20 > - mmap_read_lock(mm); > - locked =3D 1; > - vma =3D find_vma_intersection(mm, start, start + 1); > - if (!vma) { > - ret =3D -EFAULT; > - goto out; > - } > - > - /* > - * While get_vaddr_frames() could be used for transient (kernel > - * controlled lifetime) pinning of memory pages all current > - * users establish long term (userspace controlled lifetime) > - * page pinning. Treat get_vaddr_frames() like > - * get_user_pages_longterm() and disallow it for filesystem-dax > - * mappings. > - */ > - if (vma_is_fsdax(vma)) { > - ret =3D -EOPNOTSUPP; > - goto out; > - } > - > - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { By removing this check from this location, and changing from pin_user_pages_locked() to pin_user_pages_fast(), I *think* we end up losing the check entirely. Is that intended? If so it could use a comment somewhere to explain why. thanks, --=20 John Hubbard NVIDIA > + ret =3D pin_user_pages_fast(start, nr_frames, > + FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, > + (struct page **)(vec->ptrs)); > + if (ret > 0) { > vec->got_ref =3D true; > vec->is_pfns =3D false; > - ret =3D pin_user_pages_locked(start, nr_frames, > - gup_flags, (struct page **)(vec->ptrs), &locked); > - goto out; > + goto out_unlocked; > } > =20 > + mmap_read_lock(mm); > vec->got_ref =3D false; > vec->is_pfns =3D true; > + ret =3D 0; > do { > unsigned long *nums =3D frame_vector_pfns(vec); > =20 > + vma =3D find_vma_intersection(mm, start, start + 1); > + if (!vma) > + break; > + > while (ret < nr_frames && start + PAGE_SIZE <=3D vma->vm_end) { > err =3D follow_pfn(vma, start, &nums[ret]); > if (err) { > @@ -92,17 +77,13 @@ int get_vaddr_frames(unsigned long start, unsigned in= t nr_frames, > start +=3D PAGE_SIZE; > ret++; > } > - /* > - * We stop if we have enough pages or if VMA doesn't completely > - * cover the tail page. > - */ > - if (ret >=3D nr_frames || start < vma->vm_end) > + /* Bail out if VMA doesn't completely cover the tail page. */ > + if (start < vma->vm_end) > break; > - vma =3D find_vma_intersection(mm, start, start + 1); > - } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP)); > + } while (ret < nr_frames); > out: > - if (locked) > - mmap_read_unlock(mm); > + mmap_read_unlock(mm); > +out_unlocked: > if (!ret) > ret =3D -EFAULT; > if (ret > 0) >=20