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Groups > linux.kernel > #1286373 > unrolled thread
| Started by | Qais Yousef <qais.yousef@imgtec.com> |
|---|---|
| First post | 2015-12-08 11:20 +0100 |
| Last post | 2015-12-09 15:40 +0100 |
| Articles | 5 — 4 participants |
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[PATCH] MIPS: Fix DMA contiguous allocation Qais Yousef <qais.yousef@imgtec.com> - 2015-12-08 11:20 +0100
Re: [PATCH] MIPS: Fix DMA contiguous allocation Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-12-08 13:20 +0100
Re: [PATCH] MIPS: Fix DMA contiguous allocation Andrew Morton <akpm@linux-foundation.org> - 2015-12-08 23:20 +0100
Re: [PATCH] MIPS: Fix DMA contiguous allocation Mel Gorman <mgorman@techsingularity.net> - 2015-12-09 12:40 +0100
Re: [PATCH] MIPS: Fix DMA contiguous allocation Qais Yousef <qais.yousef@imgtec.com> - 2015-12-09 15:40 +0100
| From | Qais Yousef <qais.yousef@imgtec.com> |
|---|---|
| Date | 2015-12-08 11:20 +0100 |
| Subject | [PATCH] MIPS: Fix DMA contiguous allocation |
| Message-ID | <qDnxg-Xg-5@gated-at.bofh.it> |
Recent changes to how GFP_ATOMIC is defined seems to have broken the condition to use mips_alloc_from_contiguous() in mips_dma_alloc_coherent(). I couldn't bottom out the exact change but I think it's this one d0164adc89f6 (mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd) From what I see GFP_ATOMIC has multiple bits set and the check for !(gfp & GFP_ATOMIC) isn't enough. To verify if the flag is atomic we need to make sure that (gfp & GFP_ATOMIC) == GFP_ATOMIC to verify that all bits rquired to satisfy GFP_ATOMIC condition are set. Signed-off-by: Qais Yousef <qais.yousef@imgtec.com> --- arch/mips/mm/dma-default.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c index d8117be729a2..d6b8a1445a3a 100644 --- a/arch/mips/mm/dma-default.c +++ b/arch/mips/mm/dma-default.c @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size, gfp = massage_gfp_flags(dev, gfp); - if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC)) + if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC)) page = dma_alloc_from_contiguous(dev, count, get_order(size)); if (!page) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> |
|---|---|
| Date | 2015-12-08 13:20 +0100 |
| Message-ID | <qDppn-2eU-1@gated-at.bofh.it> |
| In reply to | #1286373 |
On 12/8/2015 1:18 PM, Qais Yousef wrote:
> Recent changes to how GFP_ATOMIC is defined seems to have broken the condition
> to use mips_alloc_from_contiguous() in mips_dma_alloc_coherent().
>
> I couldn't bottom out the exact change but I think it's this one
>
> d0164adc89f6 (mm, page_alloc: distinguish between being unable to sleep,
> unwilling to sleep and avoiding waking kswapd)
>
> From what I see GFP_ATOMIC has multiple bits set and the check for !(gfp
> & GFP_ATOMIC) isn't enough. To verify if the flag is atomic we need to make
> sure that (gfp & GFP_ATOMIC) == GFP_ATOMIC to verify that all bits rquired to
Required.
> satisfy GFP_ATOMIC condition are set.
>
> Signed-off-by: Qais Yousef <qais.yousef@imgtec.com>
> ---
> arch/mips/mm/dma-default.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index d8117be729a2..d6b8a1445a3a 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
> @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size,
>
> gfp = massage_gfp_flags(dev, gfp);
>
> - if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC))
> + if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC))
() around != not necessary.
[...]
MBR, Sergei
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2015-12-08 23:20 +0100 |
| Message-ID | <qDyM2-89u-9@gated-at.bofh.it> |
| In reply to | #1286373 |
On Tue, 8 Dec 2015 10:18:50 +0000 Qais Yousef <qais.yousef@imgtec.com> wrote: > Recent changes to how GFP_ATOMIC is defined seems to have broken the condition > to use mips_alloc_from_contiguous() in mips_dma_alloc_coherent(). > > I couldn't bottom out the exact change but I think it's this one > > d0164adc89f6 (mm, page_alloc: distinguish between being unable to sleep, > unwilling to sleep and avoiding waking kswapd) > > >From what I see GFP_ATOMIC has multiple bits set and the check for !(gfp > & GFP_ATOMIC) isn't enough. To verify if the flag is atomic we need to make > sure that (gfp & GFP_ATOMIC) == GFP_ATOMIC to verify that all bits rquired to > satisfy GFP_ATOMIC condition are set. > > ... > > --- a/arch/mips/mm/dma-default.c > +++ b/arch/mips/mm/dma-default.c > @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size, > > gfp = massage_gfp_flags(dev, gfp); > > - if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC)) > + if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC)) > page = dma_alloc_from_contiguous(dev, > count, get_order(size)); > if (!page) hm. It seems that the code is asking "can I do a potentially-sleeping memory allocation"? The way to do that under the new regime is if (IS_ENABLED(CONFIG_DMA_CMA) && gfpflags_allow_blocking(gfp)) Mel, can you please confirm? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Mel Gorman <mgorman@techsingularity.net> |
|---|---|
| Date | 2015-12-09 12:40 +0100 |
| Message-ID | <qDLge-7LW-5@gated-at.bofh.it> |
| In reply to | #1286894 |
On Tue, Dec 08, 2015 at 02:19:39PM -0800, Andrew Morton wrote: > On Tue, 8 Dec 2015 10:18:50 +0000 Qais Yousef <qais.yousef@imgtec.com> wrote: > > > Recent changes to how GFP_ATOMIC is defined seems to have broken the condition > > to use mips_alloc_from_contiguous() in mips_dma_alloc_coherent(). > > > > I couldn't bottom out the exact change but I think it's this one > > > > d0164adc89f6 (mm, page_alloc: distinguish between being unable to sleep, > > unwilling to sleep and avoiding waking kswapd) > > > > >From what I see GFP_ATOMIC has multiple bits set and the check for !(gfp > > & GFP_ATOMIC) isn't enough. To verify if the flag is atomic we need to make > > sure that (gfp & GFP_ATOMIC) == GFP_ATOMIC to verify that all bits rquired to > > satisfy GFP_ATOMIC condition are set. > > > > ... > > > > --- a/arch/mips/mm/dma-default.c > > +++ b/arch/mips/mm/dma-default.c > > @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size, > > > > gfp = massage_gfp_flags(dev, gfp); > > > > - if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC)) > > + if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC)) > > page = dma_alloc_from_contiguous(dev, > > count, get_order(size)); > > if (!page) > > hm. It seems that the code is asking "can I do a potentially-sleeping > memory allocation"? > > The way to do that under the new regime is > > if (IS_ENABLED(CONFIG_DMA_CMA) && gfpflags_allow_blocking(gfp)) > > Mel, can you please confirm? Yes, this is the correct way it should be checked. The full flags cover watermark and kswapd treatment which potentially could be altered by the caller. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Qais Yousef <qais.yousef@imgtec.com> |
|---|---|
| Date | 2015-12-09 15:40 +0100 |
| Message-ID | <qDO4p-1aj-9@gated-at.bofh.it> |
| In reply to | #1287431 |
On 12/09/2015 11:36 AM, Mel Gorman wrote: > On Tue, Dec 08, 2015 at 02:19:39PM -0800, Andrew Morton wrote: >> On Tue, 8 Dec 2015 10:18:50 +0000 Qais Yousef <qais.yousef@imgtec.com> wrote: >> >>> --- a/arch/mips/mm/dma-default.c >>> +++ b/arch/mips/mm/dma-default.c >>> @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size, >>> >>> gfp = massage_gfp_flags(dev, gfp); >>> >>> - if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC)) >>> + if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC)) >>> page = dma_alloc_from_contiguous(dev, >>> count, get_order(size)); >>> if (!page) >> hm. It seems that the code is asking "can I do a potentially-sleeping >> memory allocation"? >> >> The way to do that under the new regime is >> >> if (IS_ENABLED(CONFIG_DMA_CMA) && gfpflags_allow_blocking(gfp)) >> >> Mel, can you please confirm? > Yes, this is the correct way it should be checked. The full flags cover > watermark and kswapd treatment which potentially could be altered by > the caller. > OK thanks both. I'll send a revised version with this change. Thanks, Qais -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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