From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Zhao Subject: Re: [PATCH] ARM: dma: Drop __GFP_COMP for iommu dma memory allocations Date: Fri, 21 Jun 2013 12:52:40 +0800 Message-ID: <20130621045240.GH17331@rizhao-lap> References: <1371731460-15316-1-git-send-email-rizhao@nvidia.com> <51C2FDE0.4060206@cogentembedded.com> <20130620.173511.831032817734076793.hdoyu@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: In-Reply-To: <20130620.173511.831032817734076793.hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Content-Disposition: inline Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Hiroshi Doyu Cc: "linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org" , "linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org" , "m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org" , Stephen Warren , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On Thu, Jun 20, 2013 at 10:35:11PM +0800, Hiroshi Doyu wrote: > Richard Zhao wrote @ Thu, 20 Jun 2013 15:40:50 +0200: > > > >> + /* > > >> + * Following is a work-around (a.k.a. hack) to prevent pages > > >> + * with __GFP_COMP being passed to split_page() which cannot > > >> + * handle them. The real problem is that this flag probably > > >> + * should be 0 on ARM as it is not supported on this > > >> + * platform; see CONFIG_HUGETLBFS. > > >> + */ > > >> + gfp &= ~(__GFP_COMP); > > > > > > > > > Hm, what exactly is the sense you meant in using ()? > > > > It's copy/paste from elsewhere in this file. At least it's consistent? :) > > I almost sent the exact same one, actually it was under internal reivew;) Ah, sorry I didn't search internal mails but only arm mail list for related fix, since I thought it's not specific to tegra. Why not give it a Reviewed-by or Tested-by? > > This patch is similar but is the iommu version of: Exactly. Thanks Richard > > > commit ea2e7057c0234cfb8b09467d8f137760d371fc72 > Author: Sumit Bhattacharya > Date: Thu Nov 24 00:47:12 2011 +0100 > > ARM: 7172/1: dma: Drop GFP_COMP for DMA memory allocations > > dma_alloc_coherent wants to split pages after allocation in order to > reduce the memory footprint. This does not work well with GFP_COMP > pages, so drop this flag before allocation. > > This patch is ported from arch/avr32 > (commit 3611553ef985ef7c5863c8a94641738addd04cff). > > [swarren: s/HUGETLB_PAGE/HUGETLBFS/ in comment, minor comment cleanup] > > Signed-off-by: Sumit Bhattacharya > Tested-by: Varun Colbert > Signed-off-by: Stephen Warren > Signed-off-by: Russell King > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index ab58456..1aa664a 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -332,6 +332,15 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, > struct page *page; > void *addr; > > + /* > + * Following is a work-around (a.k.a. hack) to prevent pages > + * with __GFP_COMP being passed to split_page() which cannot > + * handle them. The real problem is that this flag probably > + * should be 0 on ARM as it is not supported on this > + * platform; see CONFIG_HUGETLBFS. > + */ > + gfp &= ~(__GFP_COMP); > + > *handle = ~0; > size = PAGE_ALIGN(size);