The semantics of pfn_valid() is to check presence of the memory map for a
PFN and not whether a PFN is in RAM. The memory map may be present for a
hole in the physical memory and if such hole corresponds to an MMIO range,
__arm_ioremap_pfn_caller() will produce a WARN() and fail:
Use memblock_is_map_memory() instead of pfn_valid() to check if a PFN is in
RAM or not.
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Merge tag 'fixes-2021-07-09' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock
Pull memblock fix from Mike Rapoport:
"This is a fix for the rework of ARM's pfn_valid() implementation
merged during this merge window.
Don't abuse pfn_valid() to check if pfn is in RAM
The semantics of pfn_valid() is to check presence of the memory map
for a PFN and not whether a PFN is in RAM. The memory map may be
present for a hole in the physical memory and if such hole corresponds
to an MMIO range, __arm_ioremap_pfn_caller() will produce a WARN() and
fail.
Use memblock_is_map_memory() instead of pfn_valid() to check if a PFN
is in RAM or not"
* tag 'fixes-2021-07-09' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
arm: ioremap: don't abuse pfn_valid() to check if pfn is in RAM
b6fd9e2594