The patch titled
Subject: s390/uv: convert gmap_destroy_page() from follow_page() to folio_walk
has been added to the -mm mm-unstable branch. Its filename is
s390-uv-convert-gmap_destroy_page-from-follow_page-to-folio_walk.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/s390-uv-convert-gmap_destroy_page-from-follow_page-to-folio_walk.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: s390/uv: convert gmap_destroy_page() from follow_page() to folio_walk
Date: Fri, 2 Aug 2024 17:55:21 +0200
Let's get rid of another follow_page() user and perform the UV calls under
PTL -- which likely should be fine.
No need for an additional reference while holding the PTL:
uv_destroy_folio() and uv_convert_from_secure_folio() raise the refcount,
so any concurrent make_folio_secure() would see an unexpted reference and
cannot set PG_arch_1 concurrently.
Do we really need a writable PTE? Likely yes, because the "destroy" part
is, in comparison to the export, a destructive operation. So we'll keep
the writability check for now.
We'll lose the secretmem check from follow_page(). Likely we don't care
about that here.
Link: https://lkml.kernel.org/r/20240802155524.517137-9-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/uv.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
--- a/arch/s390/kernel/uv.c~s390-uv-convert-gmap_destroy_page-from-follow_page-to-folio_walk
+++ a/arch/s390/kernel/uv.c
@@ -14,6 +14,7 @@
#include <linux/memblock.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
+#include <linux/pagewalk.h>
#include <asm/facility.h>
#include <asm/sections.h>
#include <asm/uv.h>
@@ -462,9 +463,9 @@ EXPORT_SYMBOL_GPL(gmap_convert_to_secure
int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr)
{
struct vm_area_struct *vma;
+ struct folio_walk fw;
unsigned long uaddr;
struct folio *folio;
- struct page *page;
int rc;
rc = -EFAULT;
@@ -483,11 +484,15 @@ int gmap_destroy_page(struct gmap *gmap,
goto out;
rc = 0;
- /* we take an extra reference here */
- page = follow_page(vma, uaddr, FOLL_WRITE | FOLL_GET);
- if (IS_ERR_OR_NULL(page))
+ folio = folio_walk_start(&fw, vma, uaddr, 0);
+ if (!folio)
goto out;
- folio = page_folio(page);
+ /*
+ * See gmap_make_secure(): large folios cannot be secure. Small
+ * folio implies FW_LEVEL_PTE.
+ */
+ if (folio_test_large(folio) || !pte_write(fw.pte))
+ goto out_walk_end;
rc = uv_destroy_folio(folio);
/*
* Fault handlers can race; it is possible that two CPUs will fault
@@ -500,7 +505,8 @@ int gmap_destroy_page(struct gmap *gmap,
*/
if (rc)
rc = uv_convert_from_secure_folio(folio);
- folio_put(folio);
+out_walk_end:
+ folio_walk_end(&fw, vma);
out:
mmap_read_unlock(gmap->mm);
return rc;
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-turn-use_split_pte_ptlocks-use_split_pte_ptlocks-into-kconfig-options.patch
mm-hugetlb-enforce-that-pmd-pt-sharing-has-split-pmd-pt-locks.patch
powerpc-8xx-document-and-enforce-that-split-pt-locks-are-not-used.patch
mm-simplify-arch_make_folio_accessible.patch
mm-gup-convert-to-arch_make_folio_accessible.patch
s390-uv-drop-arch_make_page_accessible.patch
mm-hugetlb-remove-hugetlb_follow_page_mask-leftover.patch
mm-rmap-cleanup-partially-mapped-handling-in-__folio_remove_rmap.patch
mm-clarify-folio_likely_mapped_shared-documentation-for-ksm-folios.patch
mm-provide-vm_normal_pagefolio_pmd-with-config_pgtable_has_huge_leaves.patch
mm-pagewalk-introduce-folio_walk_start-folio_walk_end.patch
mm-migrate-convert-do_pages_stat_array-from-follow_page-to-folio_walk.patch
mm-migrate-convert-add_page_for_migration-from-follow_page-to-folio_walk.patch
mm-ksm-convert-get_mergeable_page-from-follow_page-to-folio_walk.patch
mm-ksm-convert-scan_get_next_rmap_item-from-follow_page-to-folio_walk.patch
mm-huge_memory-convert-split_huge_pages_pid-from-follow_page-to-folio_walk.patch
s390-uv-convert-gmap_destroy_page-from-follow_page-to-folio_walk.patch
s390-mm-fault-convert-do_secure_storage_access-from-follow_page-to-folio_walk.patch
mm-remove-follow_page.patch
mm-ksm-convert-break_ksm-from-walk_page_range_vma-to-folio_walk.patch
