Hi Linus,

Please pull this single arm64 fix for 5.14. We received a report this week
that the generic version of pfn_valid(), which we switched to this merge
window in 16c9afc77660 ("arm64/mm: drop HAVE_ARCH_PFN_VALID"), interacts
badly with dma_map_resource() due to the following check:

        /* Don't allow RAM to be mapped */
        if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr))))
                return DMA_MAPPING_ERROR;

Since the ongoing saga to determine the semantics of pfn_valid() is
unlikely to be resolved this week (does it indicate valid memory, or
just the presence of a struct page, or whether that struct page has been
initialised?), just revert back to our old version of pfn_valid() for
5.14.

Thanks,

Will

--->8

The following changes since commit bde8fff82e4a4b0f000dbf4d5eadab2079be0b56:

  arm64: initialize all of CNTHCTL_EL2 (2021-08-19 10:02:10 +0100)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git tags/arm64-fixes

for you to fetch changes up to 3eb9cdffb39701743973382860f214026f4d7825:

  Partially revert "arm64/mm: drop HAVE_ARCH_PFN_VALID" (2021-08-25 11:33:24 +0100)

----------------------------------------------------------------
arm64 fix for 5.14

- Fix dma_map_resource() by reverting back to old pfn_valid() code

----------------------------------------------------------------
Will Deacon (1):
      Partially revert "arm64/mm: drop HAVE_ARCH_PFN_VALID"

 arch/arm64/Kconfig            |  1 +
 arch/arm64/include/asm/page.h |  1 +
 arch/arm64/mm/init.c          | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)

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