| Message ID | 20210126045404.2492588-3-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/vmalloc: cleanup after hugepage series | expand |
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>
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
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.
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
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); }
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(-)