This is a helper macro to loop through all the usable page sizes for a
high-granularity-enabled HugeTLB VMA. Given the VMA's hstate, it will
loop, in descending order, through the page sizes that HugeTLB supports
for this architecture. It always includes PAGE_SIZE.
This is done by looping through the hstates; however, there is no
hstate for PAGE_SIZE. To handle this case, the loop intentionally goes
out of bounds, and the out-of-bounds pointer is mapped to PAGE_SIZE.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e20df8f6216e..667e82b7a0ff 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -7941,6 +7941,24 @@ bool hugetlb_hgm_enabled(struct vm_area_struct *vma)
{
return vma && (vma->vm_flags & VM_HUGETLB_HGM);
}
+/* Should only be used by the for_each_hgm_shift macro. */
+static unsigned int __shift_for_hstate(struct hstate *h)
+{
+ /* If h is out of bounds, we have reached the end, so give PAGE_SIZE */
+ if (h >= &hstates[hugetlb_max_hstate])
+ return PAGE_SHIFT;
+ return huge_page_shift(h);
+}
+
+/*
+ * Intentionally go out of bounds. An out-of-bounds hstate will be converted to
+ * PAGE_SIZE.
+ */
+#define for_each_hgm_shift(hstate, tmp_h, shift) \
+ for ((tmp_h) = hstate; (shift) = __shift_for_hstate(tmp_h), \
+ (tmp_h) <= &hstates[hugetlb_max_hstate]; \
+ (tmp_h)++)
+
#endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */
/*
--
2.39.2.637.g21b0678d19-goog
