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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id g3si11853825pgq.61.2019.02.26.06.29.42 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 26 Feb 2019 06:29:42 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of batv+8115932e98e9c93b5750+5665+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=EOrWHMUq; spf=pass (google.com: best guess record for domain of batv+8115932e98e9c93b5750+5665+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+8115932e98e9c93b5750+5665+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=CukDaErtMT3ikoFe8SH8nKAbqlqTD7bFhtP2OfeZy5Y=; b=EOrWHMUqtP0ikAezL07GksK/z uhJsfyQ/I7noAxqyEJCtwMtHojouj/a5xYxxapv0v16KZ9KZWH6kqVfxRSNuSJyzo/MrwYLQb/H5a Ia+9jJjPx/y07Zv+3bW18J2s+w0Crl17iyBYuWI0ujqtSN4erGLTSm666kINEgvBaKYdf2Wo2fY/f WfNbgaozOX/GeX+5FKR0NaiUkj4GzT8xeditPVzSsJnSkhb+FBa2sAUTqq00fSLymZKdtAQHE8Dwa XGnvLnvbUvqXetgFyxc6JMQmNGB06MYUpsdga5XGdtvnIjRf/eA6KWzNKQKcIYUfmUpXFf1+/gUkf 4TZp9Q8Jg==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gydjp-0004PI-Q5; Tue, 26 Feb 2019 14:29:41 +0000 Date: Tue, 26 Feb 2019 06:29:41 -0800 From: Christoph Hellwig To: Gabriel Krisman Bertazi Cc: linux-mm@kvack.org, labbott@redhat.com, kernel@collabora.com, gael.portay@collabora.com, mike.kravetz@oracle.com, m.szyprowski@samsung.com Subject: Re: [PATCH 0/6] Improve handling of GFP flags in the CMA allocator Message-ID: <20190226142941.GA13684@infradead.org> References: <20190218210715.1066-1-krisman@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190218210715.1066-1-krisman@collabora.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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: I don't think this is a good idea. The whole concept of just passing random GFP_ flags to dma_alloc_attrs / dma_alloc_coherent can't work, given that on many architectures we need to set up new page tables to remap the allocated memory, and we can't use arbitrary gfp flags for pte allocations. So instead of trying to pass them further down again we need to instead work to fix all callers of dma_alloc_attrs / dma_alloc_coherent that don't just pass GFP_KERNEL.