* [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range [not found] <20210126045404.2492588-1-npiggin@gmail.com> @ 2021-01-26 4:54 ` Nicholas Piggin 2021-01-26 6:38 ` Christoph Hellwig 2021-01-26 22:08 ` Konrad Rzeszutek Wilk 0 siblings, 2 replies; 5+ messages in thread From: Nicholas Piggin @ 2021-01-26 4:54 UTC (permalink / raw) To: linux-mm, Andrew Morton Cc: linux-kernel, Nicholas Piggin, iommu, Robin Murphy, Christoph Hellwig vunmap will remove ptes. Cc: Christoph Hellwig <hch@lst.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: iommu@lists.linux-foundation.org Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- kernel/dma/remap.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c index 905c3fa005f1..b4526668072e 100644 --- a/kernel/dma/remap.c +++ b/kernel/dma/remap.c @@ -66,6 +66,5 @@ void dma_common_free_remap(void *cpu_addr, size_t size) return; } - unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size)); vunmap(cpu_addr); } -- 2.23.0 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range 2021-01-26 4:54 ` [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range Nicholas Piggin @ 2021-01-26 6:38 ` Christoph Hellwig 2021-01-26 22:08 ` Konrad Rzeszutek Wilk 1 sibling, 0 replies; 5+ messages in thread From: Christoph Hellwig @ 2021-01-26 6:38 UTC (permalink / raw) To: Nicholas Piggin Cc: linux-kernel, linux-mm, iommu, Andrew Morton, Robin Murphy, Christoph Hellwig On Tue, Jan 26, 2021 at 02:54:01PM +1000, Nicholas Piggin wrote: > vunmap will remove ptes. Looks good, Reviewed-by: Christoph Hellwig <hch@lst.de> _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range 2021-01-26 4:54 ` [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range Nicholas Piggin 2021-01-26 6:38 ` Christoph Hellwig @ 2021-01-26 22:08 ` Konrad Rzeszutek Wilk 2021-01-27 7:10 ` Christoph Hellwig 1 sibling, 1 reply; 5+ messages in thread From: Konrad Rzeszutek Wilk @ 2021-01-26 22:08 UTC (permalink / raw) To: Nicholas Piggin Cc: linux-kernel, linux-mm, iommu, Andrew Morton, Robin Murphy, Christoph Hellwig On Tue, Jan 26, 2021 at 02:54:01PM +1000, Nicholas Piggin wrote: > vunmap will remove ptes. Should there be some ASSERT after the vunmap to make sure that is the case? > > Cc: Christoph Hellwig <hch@lst.de> > Cc: Marek Szyprowski <m.szyprowski@samsung.com> > Cc: Robin Murphy <robin.murphy@arm.com> > Cc: iommu@lists.linux-foundation.org > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > kernel/dma/remap.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c > index 905c3fa005f1..b4526668072e 100644 > --- a/kernel/dma/remap.c > +++ b/kernel/dma/remap.c > @@ -66,6 +66,5 @@ void dma_common_free_remap(void *cpu_addr, size_t size) > return; > } > > - unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size)); > vunmap(cpu_addr); > } > -- > 2.23.0 > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range 2021-01-26 22:08 ` Konrad Rzeszutek Wilk @ 2021-01-27 7:10 ` Christoph Hellwig 2021-01-27 23:44 ` Nicholas Piggin 0 siblings, 1 reply; 5+ messages in thread From: Christoph Hellwig @ 2021-01-27 7:10 UTC (permalink / raw) To: Konrad Rzeszutek Wilk Cc: linux-kernel, Nicholas Piggin, linux-mm, iommu, Andrew Morton, Robin Murphy, Christoph Hellwig On Tue, Jan 26, 2021 at 05:08:46PM -0500, Konrad Rzeszutek Wilk wrote: > On Tue, Jan 26, 2021 at 02:54:01PM +1000, Nicholas Piggin wrote: > > vunmap will remove ptes. > > Should there be some ASSERT after the vunmap to make sure that is the > case? Not really. removing the PTEs is the whole point of vunmap. Everything else is just house keeping. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range 2021-01-27 7:10 ` Christoph Hellwig @ 2021-01-27 23:44 ` Nicholas Piggin 0 siblings, 0 replies; 5+ messages in thread From: Nicholas Piggin @ 2021-01-27 23:44 UTC (permalink / raw) To: Christoph Hellwig, Konrad Rzeszutek Wilk Cc: linux-mm, Andrew Morton, Robin Murphy, iommu, linux-kernel Excerpts from Christoph Hellwig's message of January 27, 2021 5:10 pm: > On Tue, Jan 26, 2021 at 05:08:46PM -0500, Konrad Rzeszutek Wilk wrote: >> On Tue, Jan 26, 2021 at 02:54:01PM +1000, Nicholas Piggin wrote: >> > vunmap will remove ptes. >> >> Should there be some ASSERT after the vunmap to make sure that is the >> case? > > Not really. removing the PTEs is the whole point of vunmap. Everything > else is just house keeping. Agree. I did double check this and wrote a quick test to check ptes were there before the vunmap and cleared after, just to make sure I didn't make a silly mistake with the patch. But in general drivers should be able to trust code behind the API call will do the right thing. Such assertions should go in the vunmap() implementation as appropriate. Thanks, Nick _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 5+ messages in thread
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[not found] <20210126045404.2492588-1-npiggin@gmail.com>
2021-01-26 4:54 ` [PATCH 2/5] kernel/dma: remove unnecessary unmap_kernel_range Nicholas Piggin
2021-01-26 6:38 ` Christoph Hellwig
2021-01-26 22:08 ` Konrad Rzeszutek Wilk
2021-01-27 7:10 ` Christoph Hellwig
2021-01-27 23:44 ` Nicholas Piggin
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