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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD647C43217 for ; Tue, 8 Nov 2022 04:46:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3EC796B0071; Mon, 7 Nov 2022 23:46:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 375158E0002; Mon, 7 Nov 2022 23:46:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 215368E0001; Mon, 7 Nov 2022 23:46:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0F73C6B0071 for ; Mon, 7 Nov 2022 23:46:15 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id D4BBCA0FB8 for ; Tue, 8 Nov 2022 04:46:14 +0000 (UTC) X-FDA: 80109038268.19.B9EE1C9 Received: from mail-ej1-f43.google.com (mail-ej1-f43.google.com [209.85.218.43]) by imf05.hostedemail.com (Postfix) with ESMTP id 69561100004 for ; Tue, 8 Nov 2022 04:46:13 +0000 (UTC) Received: by mail-ej1-f43.google.com with SMTP id y14so35517101ejd.9 for ; Mon, 07 Nov 2022 20:46:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=Fra4yIWv6TZGqY5e50Ht4t7fKg9qXIteCxj5r9JD6vc=; b=k5nrvygDjfG84Jq8usw3TAeubZw8DjisC8BDW/Nl99poBxOVm3b4Emj6HmmfjmpRDg 6UqJx+Zje8uwbw0492FSt+SP9nPZpSClhlI2a7jkV8gf4dZ+NQhHw/+vcVeKfiMshCy8 l5vHZxgwLrsSFmUFQ9k9AqBdcglrJDMAIuZNg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Fra4yIWv6TZGqY5e50Ht4t7fKg9qXIteCxj5r9JD6vc=; b=1or8vZMJgjoVrRaeYFQfkSBx1sLZ4JANC8UBwm9OJ0Z+02yFG7ASu7kXhXfFZXJPJk rBseJb6S5zN+EyE7ucvRn8elzJBdDwTciBnTLPTq0rVNmhDrw3+aRqJRj1SxjTOdaeZm rp44qnA9Dmuki9RVxHTvgsMThKe3QogdYBkufTvA3U5YUgKriJ7vjpEoSf8ojPy0ztzj ZPt/FRxuG92WbfpwJh3eX9UEnWdRMNK7Zf63uCjIiJKmv0G39SEfqpm1bXqG4GDLMFaa PcUClZNTvalqiamXhBHkPwvIxwbr/YLOIJD4BCX6WOzI3f5e9t08IqBjOLXW3+FoAgtj 4Hgw== X-Gm-Message-State: ACrzQf37wzuWcXFDIyYyNZHaO+4kwTemh/AOgDHLBVpi/xRu6+SZxMxf nTnsDahw1FcKhTx+RDcrrJ1fTShzEMThuA== X-Google-Smtp-Source: AMsMyM48mV0zojQZbAhrNT56vr4uJeTaxrScZ1T7/yZs0eiqFkGKhgK3RuX05aFnd7Blqinxp4rBnw== X-Received: by 2002:a17:907:168e:b0:7a1:6786:f16 with SMTP id hc14-20020a170907168e00b007a167860f16mr51442164ejc.590.1667882771766; Mon, 07 Nov 2022 20:46:11 -0800 (PST) Received: from mail-ej1-f41.google.com (mail-ej1-f41.google.com. [209.85.218.41]) by smtp.gmail.com with ESMTPSA id pv28-20020a170907209c00b0079e11b8e891sm4138692ejb.125.2022.11.07.20.46.09 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Nov 2022 20:46:10 -0800 (PST) Received: by mail-ej1-f41.google.com with SMTP id t25so35507946ejb.8 for ; Mon, 07 Nov 2022 20:46:09 -0800 (PST) X-Received: by 2002:a17:906:ee8e:b0:730:3646:d178 with SMTP id wt14-20020a170906ee8e00b007303646d178mr51989213ejb.426.1667882769115; Mon, 07 Nov 2022 20:46:09 -0800 (PST) MIME-Version: 1.0 References: <20221107161740.144456-1-david@redhat.com> <20221107161740.144456-17-david@redhat.com> In-Reply-To: <20221107161740.144456-17-david@redhat.com> From: Tomasz Figa Date: Tue, 8 Nov 2022 13:45:57 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH RFC 16/19] mm/frame-vector: remove FOLL_FORCE usage To: David Hildenbrand , Hans Verkuil , Marek Szyprowski Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-kselftest@vger.kernel.org, Linus Torvalds , Andrew Morton , Jason Gunthorpe , John Hubbard , Peter Xu , Greg Kroah-Hartman , Andrea Arcangeli , Hugh Dickins , Nadav Amit , Vlastimil Babka , Matthew Wilcox , Mike Kravetz , Muchun Song , Lucas Stach , David Airlie , Oded Gabbay , Arnd Bergmann , Mauro Carvalho Chehab Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667882773; a=rsa-sha256; cv=none; b=3cka4KDCZUpVl64v/yEXL78gkE5e3V/d+m5xmrCsor2aVYvsc2x0ljl3fsOAGhXzxhz6mt yIV0LZsiC5otZiYISrMhdDKtKddMgO0gvVugKj8WDXuhOLo+0TG20kuTEqjQPkuyoqG8Pc 1Yx0M1hAbIdwDcVSVK0CkF6gLECFVbk= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=k5nrvygD; spf=pass (imf05.hostedemail.com: domain of tfiga@chromium.org designates 209.85.218.43 as permitted sender) smtp.mailfrom=tfiga@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667882773; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Fra4yIWv6TZGqY5e50Ht4t7fKg9qXIteCxj5r9JD6vc=; b=EECC3UxxTvzcWFFDJTm5KEtBUUnwMmBbooOib+Hbb0K/yxEpFeuq+G6kOJIniJ0PwDQalB 55EPZTJD7lPg+Fx7uQNSwCw5kF5tKbyEUPx+IEtJ0RPplBn2ARL3RXLw4/+xfi1XUGbIRd K7Ve4amRMx0aTxGvSasgo9SiZsK2Svg= Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=k5nrvygD; spf=pass (imf05.hostedemail.com: domain of tfiga@chromium.org designates 209.85.218.43 as permitted sender) smtp.mailfrom=tfiga@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: q8pdjfowjtschda1ftcok83hacb1d6a5 X-Rspamd-Queue-Id: 69561100004 X-HE-Tag: 1667882773-734550 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: Hi David, On Tue, Nov 8, 2022 at 1:19 AM David Hildenbrand wrote: > > FOLL_FORCE is really only for debugger access. According to commit > 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are always > writable"), the pinned pages are always writable. Actually that patch is only a workaround to temporarily disable support for read-only pages as they seemed to suffer from some corruption issues in the retrieved user pages. We expect to support read-only pages as hardware input after. That said, FOLL_FORCE doesn't sound like the right thing even in that case, but I don't know the background behind it being added here in the first place. +Hans Verkuil +Marek Szyprowski do you happen to remember anything about it? Best regards, Tomasz > > FOLL_FORCE in this case seems to be a legacy leftover. Let's just remove > it. > > Cc: Tomasz Figa > Cc: Marek Szyprowski > Cc: Mauro Carvalho Chehab > Signed-off-by: David Hildenbrand > --- > drivers/media/common/videobuf2/frame_vector.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/media/common/videobuf2/frame_vector.c > index 542dde9d2609..062e98148c53 100644 > --- a/drivers/media/common/videobuf2/frame_vector.c > +++ b/drivers/media/common/videobuf2/frame_vector.c > @@ -50,7 +50,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > start = untagged_addr(start); > > ret = pin_user_pages_fast(start, nr_frames, > - FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, > + FOLL_WRITE | FOLL_LONGTERM, > (struct page **)(vec->ptrs)); > if (ret > 0) { > vec->got_ref = true; > -- > 2.38.1 >