[PATCH v2 03/14] mm/gup: Check p4d presence before going on
From: peterx@redhat.com
Date: 2024-03-18 20:04:14
Also in:
linux-arm-kernel, linux-mm, lkml, sparclinux
Subsystem:
memory management, memory management - gup (get user pages), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
From: Peter Xu <peterx@redhat.com> Currently there should have no p4d swap entries so it may not matter much, however this may help us to rule out swap entries in pXd_huge() API, which will include p4d_huge(). The p4d_present() checks make it 100% clear that we won't rely on p4d_huge() for swap entries. Signed-off-by: Peter Xu <peterx@redhat.com> --- mm/gup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 69a777f4fc5c..802987281b2f 100644
--- a/mm/gup.c
+++ b/mm/gup.c@@ -776,7 +776,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma, p4dp = p4d_offset(pgdp, address); p4d = READ_ONCE(*p4dp); - if (p4d_none(p4d)) + if (!p4d_present(p4d)) return no_page_table(vma, flags); BUILD_BUG_ON(p4d_huge(p4d)); if (unlikely(p4d_bad(p4d)))
@@ -3069,7 +3069,7 @@ static int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, unsigned lo p4d_t p4d = READ_ONCE(*p4dp); next = p4d_addr_end(addr, end); - if (p4d_none(p4d)) + if (!p4d_present(p4d)) return 0; BUILD_BUG_ON(p4d_huge(p4d)); if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) {
--
2.44.0