On 6/29/26 14:23, Lorenzo Stoakes wrote: > Describe what vma_start_pgoff() and vma_last_pgoff() actually provide in > detail. > > This is in order that we can differentiate this between functions that will > be added in a subsequent patch which provide a different page offset. > > No functional change intended. > > Signed-off-by: Lorenzo Stoakes <[email protected]> > --- > include/linux/mm.h | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 059144435729..2f00c75e66bd 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -4278,11 +4278,37 @@ static inline unsigned long vma_pages(const struct > vm_area_struct *vma) > return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; > } > > +/** > + * vma_start_pgoff() - Get the page offset of the start of @vma > + * @vma: The VMA whose page offset is required. > + * > + * If the VMA is file-backed, this is the page offset into the file. > + * > + * If the VMA is anonymous, this is the virtual page offset of the start of > the > + * VMA - if unfaulted, then vma->vm_start >> PAGE_SHIFT, if faulted then the > + * virtual page offset at the time of first fault. > + * > + * Note that if @vma is a MAP_PRIVATE file-backed mapping, then this returns > the > + * file offset.
There is the ugly case of @vma being a MAP_PRIVATE PFNMAP mapping, where it returns something different. (remap_pfn_range_prepare_vma() -> vma->vm_pgoff set to PFN) -- Cheers, David
