On 21.04.22 9:43, Greg KH wrote:
On Wed, Apr 20, 2022 at 05:43:40AM -0700, Georgi Djakov wrote:
From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
[ Upstream commit a9c38c5d267cb94871dfa2de5539c92025c855d7 ]
dma_map_resource() uses pfn_valid() to ensure the range is not RAM.
However, pfn_valid() only checks for availability of the memory map for a
PFN but it does not ensure that the PFN is actually backed by RAM.
As dma_map_resource() is the only method in DMA mapping APIs that has this
check, simply drop the pfn_valid() test from dma_map_resource().
Link: https://lore.kernel.org/all/20210824173741.GC623@xxxxxxx/
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210930013039.11260-2-rppt@xxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Fixes: 859a85ddf90e ("mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE")
Link: https://lore.kernel.org/r/Yl0IZWT2nsiYtqBT@xxxxxxxxxxxxx
Signed-off-by: Georgi Djakov <quic_c_gdjako@xxxxxxxxxxx>
---
kernel/dma/mapping.c | 4 ----
1 file changed, 4 deletions(-)
I took this, but I do not understand why patch 2/2 in this series is
needed, as Sasha points out. Cleanups are nice, but is it necessary
here?
It's needed as it removes the "select HAVE_ARCH_PFN_VALID" from the arm64/Kconfig.
This will make us use the generic pfn_valid() function in mmzone.h, instead of the
arch-specific one, that we are dropping.
Thanks,
Georgi
