Messages in this thread | | | Date | Wed, 21 Nov 2012 10:20:07 +0100 | From | Marek Szyprowski <> | Subject | Re: [PATCH v2] mm: dmapool: use provided gfp flags for all dma_alloc_coherent() calls |
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Hello,
On 11/21/2012 9:36 AM, Andrew Morton wrote: > On Wed, 21 Nov 2012 09:08:52 +0100 Marek Szyprowski <m.szyprowski@samsung.com> wrote: > > > Hello, > > > > On 11/20/2012 8:33 PM, Andrew Morton wrote: > > > On Tue, 20 Nov 2012 15:31:45 +0100 > > > Marek Szyprowski <m.szyprowski@samsung.com> wrote: > > > > > > > dmapool always calls dma_alloc_coherent() with GFP_ATOMIC flag, > > > > regardless the flags provided by the caller. This causes excessive > > > > pruning of emergency memory pools without any good reason. Additionaly, > > > > on ARM architecture any driver which is using dmapools will sooner or > > > > later trigger the following error: > > > > "ERROR: 256 KiB atomic DMA coherent pool is too small! > > > > Please increase it with coherent_pool= kernel parameter!". > > > > Increasing the coherent pool size usually doesn't help much and only > > > > delays such error, because all GFP_ATOMIC DMA allocations are always > > > > served from the special, very limited memory pool. > > > > > > > > > > Is this problem serious enough to justify merging the patch into 3.7? > > > And into -stable kernels? > > > > I wonder if it is a good idea to merge such change at the end of current > > -rc period. > > I'm not sure what you mean by this. > > But what we do sometimes if we think a patch needs a bit more > real-world testing before backporting is to merge it into -rc1 in the > normal merge window, and tag it for -stable backporting. That way it > gets a few weeks(?) testing in mainline before getting backported.
I just wondered that if it gets merged to v3.7-rc7 there won't be much time for real-world testing before final v3.7 release. This patch is in linux-next for over a week and I'm not aware of any issues, but -rc releases gets much more attention and testing than linux-next tree.
If You think it's fine to put such change to v3.7-rc7 I will send a pull request and tag it for stable asap.
Best regards -- Marek Szyprowski Samsung Poland R&D Center
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