The quilt patch titled
Subject: mm/huge_memory: convert split_huge_pages_pid() from follow_page() to folio_walk
has been removed from the -mm tree. Its filename was
mm-huge_memory-convert-split_huge_pages_pid-from-follow_page-to-folio_walk.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/huge_memory: convert split_huge_pages_pid() from follow_page() to folio_walk
Date: Fri, 2 Aug 2024 17:55:20 +0200
Let's remove yet another follow_page() user. Note that we have to do the
split without holding the PTL, after folio_walk_end(). We don't care
about losing the secretmem check in follow_page().
[david@xxxxxxxxxx: teach can_split_folio() that we are not holding an additional reference]
Link: https://lkml.kernel.org/r/c75d1c6c-8ea6-424f-853c-1ccda6c77ba2@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20240802155524.517137-8-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Janosch Frank <frankja@xxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/huge_mm.h | 4 ++--
mm/huge_memory.c | 27 ++++++++++++++++-----------
mm/vmscan.c | 2 +-
3 files changed, 19 insertions(+), 14 deletions(-)
--- a/include/linux/huge_mm.h~mm-huge_memory-convert-split_huge_pages_pid-from-follow_page-to-folio_walk
+++ a/include/linux/huge_mm.h
@@ -314,7 +314,7 @@ unsigned long thp_get_unmapped_area_vmfl
unsigned long len, unsigned long pgoff, unsigned long flags,
vm_flags_t vm_flags);
-bool can_split_folio(struct folio *folio, int *pextra_pins);
+bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins);
int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
unsigned int new_order);
static inline int split_huge_page(struct page *page)
@@ -470,7 +470,7 @@ thp_get_unmapped_area_vmflags(struct fil
}
static inline bool
-can_split_folio(struct folio *folio, int *pextra_pins)
+can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins)
{
return false;
}
--- a/mm/huge_memory.c~mm-huge_memory-convert-split_huge_pages_pid-from-follow_page-to-folio_walk
+++ a/mm/huge_memory.c
@@ -40,6 +40,7 @@
#include <linux/memory-tiers.h>
#include <linux/compat.h>
#include <linux/pgalloc_tag.h>
+#include <linux/pagewalk.h>
#include <asm/tlb.h>
#include <asm/pgalloc.h>
@@ -3017,7 +3018,7 @@ static void __split_huge_page(struct pag
}
/* Racy check whether the huge page can be split */
-bool can_split_folio(struct folio *folio, int *pextra_pins)
+bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins)
{
int extra_pins;
@@ -3029,7 +3030,8 @@ bool can_split_folio(struct folio *folio
extra_pins = folio_nr_pages(folio);
if (pextra_pins)
*pextra_pins = extra_pins;
- return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1;
+ return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins -
+ caller_pins;
}
/*
@@ -3197,7 +3199,7 @@ int split_huge_page_to_list_to_order(str
* Racy check if we can split the page, before unmap_folio() will
* split PMDs
*/
- if (!can_split_folio(folio, &extra_pins)) {
+ if (!can_split_folio(folio, 1, &extra_pins)) {
ret = -EAGAIN;
goto out_unlock;
}
@@ -3504,7 +3506,7 @@ static int split_huge_pages_pid(int pid,
*/
for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
struct vm_area_struct *vma = vma_lookup(mm, addr);
- struct page *page;
+ struct folio_walk fw;
struct folio *folio;
if (!vma)
@@ -3516,13 +3518,10 @@ static int split_huge_pages_pid(int pid,
continue;
}
- /* FOLL_DUMP to ignore special (like zero) pages */
- page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
-
- if (IS_ERR_OR_NULL(page))
+ folio = folio_walk_start(&fw, vma, addr, 0);
+ if (!folio)
continue;
- folio = page_folio(page);
if (!is_transparent_hugepage(folio))
goto next;
@@ -3536,18 +3535,24 @@ static int split_huge_pages_pid(int pid,
* can be split or not. So skip the check here.
*/
if (!folio_test_private(folio) &&
- !can_split_folio(folio, NULL))
+ !can_split_folio(folio, 0, NULL))
goto next;
if (!folio_trylock(folio))
goto next;
+ folio_get(folio);
+ folio_walk_end(&fw, vma);
if (!split_folio_to_order(folio, new_order))
split++;
folio_unlock(folio);
-next:
folio_put(folio);
+
+ cond_resched();
+ continue;
+next:
+ folio_walk_end(&fw, vma);
cond_resched();
}
mmap_read_unlock(mm);
--- a/mm/vmscan.c~mm-huge_memory-convert-split_huge_pages_pid-from-follow_page-to-folio_walk
+++ a/mm/vmscan.c
@@ -1227,7 +1227,7 @@ retry:
goto keep_locked;
if (folio_test_large(folio)) {
/* cannot split folio, skip it */
- if (!can_split_folio(folio, NULL))
+ if (!can_split_folio(folio, 1, NULL))
goto activate_locked;
/*
* Split partially mapped folios right away.
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-rmap-use-folio-_mapcount-for-small-folios.patch
mm-always-inline-_compound_head-with-config_hugetlb_page_optimize_vmemmap=y.patch
selftests-mm-fix-charge_reserved_hugetlbsh-test.patch
