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[212.51.149.33]) by smtp.gmail.com with ESMTPSA id jw17-20020a17090776b100b0078b1ff41f05sm6758790ejc.43.2022.11.16.02.50.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Nov 2022 02:50:33 -0800 (PST) Date: Wed, 16 Nov 2022 11:50:31 +0100 From: Daniel Vetter To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, Greg Kroah-Hartman , dri-devel@lists.freedesktop.org, Hans Verkuil , linux-mm@kvack.org, Nadav Amit , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , Marek Szyprowski , Andrea Arcangeli , linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, x86@kernel.org, Hugh Dickins , Matthew Wilcox , Christoph Hellwig , Jason Gunthorpe , Vlastimil Babka , linux-media@vger.kernel.org, Arnd Bergmann , John Hubbard , linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, Alex Williamson , Peter Xu , Muchun Song , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, Oded Gabbay , linux-mips@vger.kernel.org, Tomasz Figa , linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , Mike Kravetz Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage Message-ID: Mail-Followup-To: David Hildenbrand , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, Greg Kroah-Hartman , dri-devel@lists.freedesktop.org, Hans Verkuil , linux-mm@kvack.org, Nadav Amit , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , Marek Szyprowski , Andrea Arcangeli , linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, x86@kernel.org, Hugh Dickins , Matthew Wilcox , Christoph Hellwig , Jason Gunthorpe , Vlastimil Babka , linux-media@vger.kernel.org, Arnd Bergmann , John Hubbard , linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, Alex Williamson , Peter Xu , Muchun Song , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, Oded Gabbay , linux-mips@vger.kernel.org, Tomasz Figa , linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , Mike Kravetz References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-17-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221116102659.70287-17-david@redhat.com> X-Operating-System: Linux phenom 5.19.0-2-amd64 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668595835; a=rsa-sha256; cv=none; b=l7ngJC6w0jyPe4Jpx5Vt7g27GQYMUuyGtpGFkzntKhcZOwYHlGpurxesKsw1bcyqtJ3NJY 0j+NdJdfW8qYo+nL2u8nCLg4qdgC9evDJk4DxX7lHjGM1MD2oMHSOGUfYzSnGkyJm6ArDx mz6EAuPIcxxFAv5bFtPRNDUnNDOkkzE= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=ffwll.ch header.s=google header.b=f2SpOZdE; dmarc=none; spf=none (imf22.hostedemail.com: domain of daniel@ffwll.ch has no SPF policy when checking 209.85.218.47) smtp.mailfrom=daniel@ffwll.ch ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668595835; 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=mdwJ/650wADnRoR72oyZkQ8DiIzSWQSpq6IdxtCR+gY=; b=P8wLRTJytY5STLKmLCPR3w3ThH/ysrrJWMfDPJ512cJ0Ji5y/qg6K1Yj2Bm4ztTSOSuMQL PpLV67XBD71x8iq6xwUyA2DcFn1AIQu4+MrTuABL9ieoyRw7jxx53RZkR9epZXzPgdljx1 gFUq0hcHAEfi0VvX9YoLnLmrINw1cuA= X-Stat-Signature: 816h3b9csw1j6yjfw9c46ng5wqouqi86 X-Rspamd-Queue-Id: 52010C000C Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=ffwll.ch header.s=google header.b=f2SpOZdE; dmarc=none; spf=none (imf22.hostedemail.com: domain of daniel@ffwll.ch has no SPF policy when checking 209.85.218.47) smtp.mailfrom=daniel@ffwll.ch X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1668595835-159420 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 Wed, Nov 16, 2022 at 11:26:55AM +0100, David Hildenbrand wrote: > FOLL_FORCE is really only for ptrace access. According to commit > 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are always > writable"), get_vaddr_frames() currently pins all pages writable as a > workaround for issues with read-only buffers. > > FOLL_FORCE, however, seems to be a legacy leftover as it predates > commit 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are > always writable"). Let's just remove it. > > Once the read-only buffer issue has been resolved, FOLL_WRITE could > again be set depending on the DMA direction. > > Cc: Hans Verkuil > Cc: Marek Szyprowski > Cc: Tomasz Figa > Cc: Marek Szyprowski > Cc: Mauro Carvalho Chehab > Signed-off-by: David Hildenbrand Also code I looked at while looking at follow_pfn stuff Reviewed-by: Daniel Vetter > --- > 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 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch