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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id o188si8782059pgo.489.2019.05.10.10.35.30 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 10 May 2019 10:35:31 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@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=WnkWtS2C; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@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=H5lczeQR8T5im5nV/9sUhsnPFlc2c+myFo/mTa3LOKU=; b=WnkWtS2CsC+hpRDe5xAbSM/mG g4nTR835iYsDU702mbLsKjHu50iincTcRK28E2pRxEGbtloA2jSjanRQ83QXjjCAWxGwNJPFV1ZSH 3RK89oHRcPwBKRcWMA58Xl0h+Ksjd2DMRR7DfESpEM8Cug9fdc90MHzOS/IJj5nnFuAEeflO82O3m EzZnbWaYauZ0lG+2g24WXNpMc+qm+b9VJO1siUOxh+WQF2IMdPsulQ6BNKwt1csNUlkm65Ahr0XYX 3HXpFOIlUhKyig7/b+1qoDCoA2oKx29FmpVoUB7VDr60Bqutaqj7FJhhCs+cAwoiDA3GSupXNH0l4 dZIIZql2A==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hP9Qf-0001w4-MO; Fri, 10 May 2019 17:35:29 +0000 Date: Fri, 10 May 2019 10:35:29 -0700 From: Matthew Wilcox To: Christoph Hellwig Cc: David Howells , Jesper Dangaard Brouer , Christoph Lameter , Andrew Morton , linux-mm Subject: Re: Bulk kmalloc Message-ID: <20190510173529.GA24921@bombadil.infradead.org> References: <20190510135031.1e8908fd@carbon> <14647.1557415738@warthog.procyon.org.uk> <3261.1557505403@warthog.procyon.org.uk> <20190510165001.GA3162@bombadil.infradead.org> <20190510171110.GA3449@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190510171110.GA3449@infradead.org> User-Agent: Mutt/1.9.2 (2017-12-15) 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 Fri, May 10, 2019 at 10:11:10AM -0700, Christoph Hellwig wrote: > On Fri, May 10, 2019 at 09:50:01AM -0700, Matthew Wilcox wrote: > > kvmalloc() is the normal solution here. Usual reasons for not being > > able to do that would be that you do DMA to the memory or that you need > > to be able to free each of these objects individually. > > Note that you absolutely can do DMA to vmalloced buffers. It just is > very painful due to the manual coherency management.. ... and we don't have proper APIs for it. The last time we discussed it was January, I think. https://lore.kernel.org/patchwork/patch/1033921/ I haven't made any effort to try to come up with decent APIs for this.