hugetlb rmap handling differs quite a lot from "ordinary" rmap code.
For example, hugetlb currently only supports entire mappings, and treats
any mapping as mapped using a single "logical PTE". Let's move it out
of the way so we can overhaul our "ordinary" rmap.
implementation/interface.
Right now we're using page_dup_file_rmap() in some cases where "ordinary"
rmap code would have used page_add_file_rmap(). So let's introduce and
use hugetlb_add_file_rmap() instead. We won't be adding a
"hugetlb_dup_file_rmap()" functon for the fork() case, as it would be
doing the same: "dup" is just an optimization for "add".
What remains is a single page_dup_file_rmap() call in fork() code.
Add sanity checks that we end up with the right folios in the right
functions.
Reviewed-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
include/linux/rmap.h | 8 ++++++++
mm/hugetlb.c | 6 +++---
mm/migrate.c | 2 +-
mm/rmap.c | 1 +
4 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 64ae6c4d72720..56900a16f41a6 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -211,6 +211,14 @@ void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *,
void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
unsigned long address);
+static inline void hugetlb_add_file_rmap(struct folio *folio)
+{
+ VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
+ VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
+
+ atomic_inc(&folio->_entire_mapcount);
+}
+
static inline void hugetlb_remove_rmap(struct folio *folio)
{
VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ef48ae6738909..57e8981879314 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5408,7 +5408,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
* sleep during the process.
*/
if (!folio_test_anon(pte_folio)) {
- page_dup_file_rmap(&pte_folio->page, true);
+ hugetlb_add_file_rmap(pte_folio);
} else if (page_try_dup_anon_rmap(&pte_folio->page,
true, src_vma)) {
pte_t src_pte_old = entry;
@@ -6279,7 +6279,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
if (anon_rmap)
hugetlb_add_new_anon_rmap(folio, vma, haddr);
else
- page_dup_file_rmap(&folio->page, true);
+ hugetlb_add_file_rmap(folio);
new_pte = make_huge_pte(vma, &folio->page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
/*
@@ -6730,7 +6730,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
goto out_release_unlock;
if (folio_in_pagecache)
- page_dup_file_rmap(&folio->page, true);
+ hugetlb_add_file_rmap(folio);
else
hugetlb_add_new_anon_rmap(folio, dst_vma, dst_addr);
diff --git a/mm/migrate.c b/mm/migrate.c
index 7d1c3f292d24d..0e912443a18c3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -252,7 +252,7 @@ static bool remove_migration_pte(struct folio *folio,
hugetlb_add_anon_rmap(folio, vma, pvmw.address,
rmap_flags);
else
- page_dup_file_rmap(new, true);
+ hugetlb_add_file_rmap(folio);
set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte,
psize);
} else
diff --git a/mm/rmap.c b/mm/rmap.c
index 261e1af0d254f..a57ec926daf0c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1395,6 +1395,7 @@ void folio_add_file_rmap_range(struct folio *folio, struct page *page,
unsigned int nr_pmdmapped = 0, first;
int nr = 0;
+ VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
/* Is page being mapped by PTE? Is this its first map to be added? */
--
2.43.0
