[RFC PATCH 1/8] mm/mmap: Teach generic_get_unmapped_area{_topdown} to handle hugetlb mappings

Oscar Salvador
2024-07-10T10:51:28Z

through generic channels, so teach generic_get_unmapped_area{_topdown}
to handle those.
The main difference is that we set info.align_mask for huge mappings.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
include/linux/hugetlb.h | 10 ++++++++++
mm/mmap.c | 4 ++++
2 files changed, 14 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 2b3c3a404769..1c7b0b32ff7e 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -1029,9 +1029,19 @@ void hugetlb_unregister_node(struct node *node);
*/
bool is_raw_hwpoison_page_in_hugepage(struct page *page);

+static inline unsigned long huge_page_mask_align(struct file *file)
+{
+ return PAGE_MASK & ~huge_page_mask(hstate_file(file));
+}
+
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};

+static inline unsigned long huge_page_mask_align(struct file *file)
+{
+ return 0;
+}
+
static inline struct hugepage_subpool *hugetlb_folio_subpool(struct folio *folio)
{
return NULL;
diff --git a/mm/mmap.c b/mm/mmap.c
index 83b4682ec85c..09131b705e7b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1743,6 +1743,8 @@ generic_get_unmapped_area(struct file *filp, unsigned long addr,
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = mmap_end;
+ if (filp && is_file_hugepages(filp))
+ info.align_mask = huge_page_mask_align(filp);
return vm_unmapped_area(&info);
}

@@ -1791,6 +1793,8 @@ generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
info.length = len;
info.low_limit = PAGE_SIZE;
info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
+ if (filp && is_file_hugepages(filp))
+ info.align_mask = huge_page_mask_align(filp);
addr = vm_unmapped_area(&info);

/*
--
2.45.2