| Message ID | 20210421065108.1987-2-rppt@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: drop pfn_valid_within() and simplify pfn_valid() | expand |
On 4/21/21 12:21 PM, Mike Rapoport wrote: > From: Mike Rapoport <rppt@linux.ibm.com> > > Add comment describing the semantics of pfn_valid() that clarifies that > pfn_valid() only checks for availability of a memory map entry (i.e. struct > page) for a PFN rather than availability of usable memory backing that PFN. > > The most "generic" version of pfn_valid() used by the configurations with > SPARSEMEM enabled resides in include/linux/mmzone.h so this is the most > suitable place for documentation about semantics of pfn_valid(). > > Suggested-by: Anshuman Khandual <anshuman.khandual@arm.com> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > include/linux/mmzone.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 47946cec7584..961f0eeefb62 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1410,6 +1410,17 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) > #endif > > #ifndef CONFIG_HAVE_ARCH_PFN_VALID > +/** > + * pfn_valid - check if there is a valid memory map entry for a PFN > + * @pfn: the page frame number to check > + * > + * Check if there is a valid memory map entry aka struct page for the @pfn. > + * Note, that availability of the memory map entry does not imply that > + * there is actual usable memory at that @pfn. The struct page may > + * represent a hole or an unusable page frame. > + * > + * Return: 1 for PFNs that have memory map entries and 0 otherwise > + */ > static inline int pfn_valid(unsigned long pfn) > { > struct mem_section *ms; >
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 47946cec7584..961f0eeefb62 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1410,6 +1410,17 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) #endif #ifndef CONFIG_HAVE_ARCH_PFN_VALID +/** + * pfn_valid - check if there is a valid memory map entry for a PFN + * @pfn: the page frame number to check + * + * Check if there is a valid memory map entry aka struct page for the @pfn. + * Note, that availability of the memory map entry does not imply that + * there is actual usable memory at that @pfn. The struct page may + * represent a hole or an unusable page frame. + * + * Return: 1 for PFNs that have memory map entries and 0 otherwise + */ static inline int pfn_valid(unsigned long pfn) { struct mem_section *ms;