On 4/7/21 10:56 PM, Mike Rapoport wrote: > From: Mike Rapoport <rppt@xxxxxxxxxxxxx> > > The arm64's version of pfn_valid() differs from the generic because of two > reasons: > > * Parts of the memory map are freed during boot. This makes it necessary to > verify that there is actual physical memory that corresponds to a pfn > which is done by querying memblock. > > * There are NOMAP memory regions. These regions are not mapped in the > linear map and until the previous commit the struct pages representing > these areas had default values. > > As the consequence of absence of the special treatment of NOMAP regions in > the memory map it was necessary to use memblock_is_map_memory() in > pfn_valid() and to have pfn_valid_within() aliased to pfn_valid() so that > generic mm functionality would not treat a NOMAP page as a normal page. > > Since the NOMAP regions are now marked as PageReserved(), pfn walkers and > the rest of core mm will treat them as unusable memory and thus > pfn_valid_within() is no longer required at all and can be disabled by > removing CONFIG_HOLES_IN_ZONE on arm64. But what about the memory map that are freed during boot (mentioned above). Would not they still cause CONFIG_HOLES_IN_ZONE to be applicable and hence pfn_valid_within() ? > > pfn_valid() can be slightly simplified by replacing > memblock_is_map_memory() with memblock_is_memory(). Just to understand this better, pfn_valid() will now return true for all MEMBLOCK_NOMAP based memory but that is okay as core MM would still ignore them as unusable memory for being PageReserved(). > > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > arch/arm64/Kconfig | 3 --- > arch/arm64/mm/init.c | 4 ++-- > 2 files changed, 2 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index e4e1b6550115..58e439046d05 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -1040,9 +1040,6 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK > def_bool y > depends on NUMA > > -config HOLES_IN_ZONE > - def_bool y > - > source "kernel/Kconfig.hz" > > config ARCH_SPARSEMEM_ENABLE > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 258b1905ed4a..bb6dd406b1f0 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -243,7 +243,7 @@ int pfn_valid(unsigned long pfn) > > /* > * ZONE_DEVICE memory does not have the memblock entries. > - * memblock_is_map_memory() check for ZONE_DEVICE based > + * memblock_is_memory() check for ZONE_DEVICE based > * addresses will always fail. Even the normal hotplugged > * memory will never have MEMBLOCK_NOMAP flag set in their > * memblock entries. Skip memblock search for all non early > @@ -254,7 +254,7 @@ int pfn_valid(unsigned long pfn) > return pfn_section_valid(ms, pfn); > } > #endif > - return memblock_is_map_memory(addr); > + return memblock_is_memory(addr); > } > EXPORT_SYMBOL(pfn_valid); > > _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
