On 6/30/26 2:18 PM, Gregory Price wrote: > Memory hotplug operations require ranges aligned to memory block > boundaries. This is a generic operation for hotplug. > > Add memory_block_aligned_range() as a common helper in <linux/memory.h> > that aligns the start address up and end address down to memory block > boundaries. Guard against end underflow when the range falls below the > first memory block boundary, returning an empty range instead. > > Update dax/kmem to use this helper. > > Signed-off-by: Gregory Price <[email protected]> > Acked-by: David Hildenbrand (Arm) <[email protected]> Reviewed-by: Dave Jiang <[email protected]> > --- > drivers/dax/kmem.c | 4 +--- > include/linux/memory.h | 27 +++++++++++++++++++++++++++ > 2 files changed, 28 insertions(+), 3 deletions(-) > > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c > index a18e2b968e4d..592171ec10f4 100644 > --- a/drivers/dax/kmem.c > +++ b/drivers/dax/kmem.c > @@ -33,9 +33,7 @@ static int dax_kmem_range(struct dev_dax *dev_dax, int i, > struct range *r) > struct dev_dax_range *dax_range = &dev_dax->ranges[i]; > struct range *range = &dax_range->range; > > - /* memory-block align the hotplug range */ > - r->start = ALIGN(range->start, memory_block_size_bytes()); > - r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1; > + *r = memory_block_aligned_range(range); > if (r->start >= r->end) { > r->start = range->start; > r->end = range->end; > diff --git a/include/linux/memory.h b/include/linux/memory.h > index 463dc02f6cff..1783299073e4 100644 > --- a/include/linux/memory.h > +++ b/include/linux/memory.h > @@ -20,6 +20,7 @@ > #include <linux/compiler.h> > #include <linux/mutex.h> > #include <linux/memory_hotplug.h> > +#include <linux/range.h> > > #define MIN_MEMORY_BLOCK_SIZE (1UL << SECTION_SIZE_BITS) > > @@ -100,6 +101,32 @@ int arch_get_memory_phys_device(unsigned long start_pfn); > unsigned long memory_block_size_bytes(void); > int set_memory_block_size_order(unsigned int order); > > +/** > + * memory_block_aligned_range - align a physical address range to memory > blocks > + * @range: the input range to align > + * > + * Aligns the start address up and the end address down to memory block > + * boundaries. This is required for memory hotplug operations which must > + * operate on memory-block aligned ranges. > + * > + * Returns the aligned range. Callers should check that the returned > + * range is valid (aligned.start < aligned.end) before using it. > + */ > +static inline struct range memory_block_aligned_range(const struct range > *range) > +{ > + struct range aligned; > + > + aligned.start = ALIGN(range->start, memory_block_size_bytes()); > + aligned.end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()); > + /* No whole block fits (e.g. range below the first boundary): empty. */ > + if (aligned.end <= aligned.start) > + aligned.start = aligned.end; > + else > + aligned.end -= 1; > + > + return aligned; > +} > + > struct memory_notify { > unsigned long start_pfn; > unsigned long nr_pages;
