The patch titled
Subject: mm: fix some minor per-VMA lock issues in userfaultfd
has been added to the -mm mm-unstable branch. Its filename is
mm-fix-some-minor-per-vma-lock-issues-in-userfaultfd.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-some-minor-per-vma-lock-issues-in-userfaultfd.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: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: fix some minor per-VMA lock issues in userfaultfd
Date: Fri, 26 Apr 2024 15:45:02 +0100
Rename lock_vma() to uffd_lock_vma() because it really is uffd specific.
Remove comment referencing unlock_vma() which doesn't exist. Fix the
comment about lock_vma_under_rcu() which I just made incorrect.
Link: https://lkml.kernel.org/r/20240426144506.1290619-4-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/userfaultfd.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
--- a/mm/userfaultfd.c~mm-fix-some-minor-per-vma-lock-issues-in-userfaultfd
+++ a/mm/userfaultfd.c
@@ -56,17 +56,16 @@ struct vm_area_struct *find_vma_and_prep
#ifdef CONFIG_PER_VMA_LOCK
/*
- * lock_vma() - Lookup and lock vma corresponding to @address.
+ * uffd_lock_vma() - Lookup and lock vma corresponding to @address.
* @mm: mm to search vma in.
* @address: address that the vma should contain.
*
- * Should be called without holding mmap_lock. vma should be unlocked after use
- * with unlock_vma().
+ * Should be called without holding mmap_lock.
*
* Return: A locked vma containing @address, -ENOENT if no vma is found, or
* -ENOMEM if anon_vma couldn't be allocated.
*/
-static struct vm_area_struct *lock_vma(struct mm_struct *mm,
+static struct vm_area_struct *uffd_lock_vma(struct mm_struct *mm,
unsigned long address)
{
struct vm_area_struct *vma;
@@ -74,9 +73,8 @@ static struct vm_area_struct *lock_vma(s
vma = lock_vma_under_rcu(mm, address);
if (vma) {
/*
- * lock_vma_under_rcu() only checks anon_vma for private
- * anonymous mappings. But we need to ensure it is assigned in
- * private file-backed vmas as well.
+ * We know we're going to need to use anon_vma, so check
+ * that early.
*/
if (!(vma->vm_flags & VM_SHARED) && unlikely(!vma->anon_vma))
vma_end_read(vma);
@@ -107,7 +105,7 @@ static struct vm_area_struct *uffd_mfill
{
struct vm_area_struct *dst_vma;
- dst_vma = lock_vma(dst_mm, dst_start);
+ dst_vma = uffd_lock_vma(dst_mm, dst_start);
if (IS_ERR(dst_vma) || validate_dst_vma(dst_vma, dst_start + len))
return dst_vma;
@@ -1401,7 +1399,7 @@ static int uffd_move_lock(struct mm_stru
struct vm_area_struct *vma;
int err;
- vma = lock_vma(mm, dst_start);
+ vma = uffd_lock_vma(mm, dst_start);
if (IS_ERR(vma))
return PTR_ERR(vma);
@@ -1416,7 +1414,7 @@ static int uffd_move_lock(struct mm_stru
}
/*
- * Using lock_vma() to get src_vma can lead to following deadlock:
+ * Using uffd_lock_vma() to get src_vma can lead to following deadlock:
*
* Thread1 Thread2
* ------- -------
@@ -1438,7 +1436,7 @@ static int uffd_move_lock(struct mm_stru
err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap);
if (!err) {
/*
- * See comment in lock_vma() as to why not using
+ * See comment in uffd_lock_vma() as to why not using
* vma_start_read() here.
*/
down_read(&(*dst_vmap)->vm_lock->lock);
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
doc-improve-the-description-of-__folio_mark_dirty.patch
buffer-add-kernel-doc-for-block_dirty_folio.patch
buffer-add-kernel-doc-for-try_to_free_buffers.patch
buffer-fix-__bread-and-__bread_gfp-kernel-doc.patch
buffer-add-kernel-doc-for-brelse-and-__brelse.patch
buffer-add-kernel-doc-for-bforget-and-__bforget.patch
buffer-improve-bdev_getblk-documentation.patch
doc-split-bufferrst-out-of-api-summaryrst.patch
doc-split-bufferrst-out-of-api-summaryrst-fix.patch
mm-memory-failure-remove-fsdax_pgoff-argument-from-__add_to_kill.patch
mm-memory-failure-pass-addr-to-__add_to_kill.patch
mm-return-the-address-from-page_mapped_in_vma.patch
mm-make-page_mapped_in_vma-conditional-on-config_memory_failure.patch
mm-memory-failure-convert-shake_page-to-shake_folio.patch
mm-convert-hugetlb_page_mapping_lock_write-to-folio.patch
mm-memory-failure-convert-memory_failure-to-use-a-folio.patch
mm-memory-failure-convert-hwpoison_user_mappings-to-take-a-folio.patch
mm-memory-failure-add-some-folio-conversions-to-unpoison_memory.patch
mm-memory-failure-use-folio-functions-throughout-collect_procs.patch
mm-memory-failure-pass-the-folio-to-collect_procs_ksm.patch
fscrypt-convert-bh_get_inode_and_lblk_num-to-use-a-folio.patch
f2fs-convert-f2fs_clear_page_cache_dirty_tag-to-use-a-folio.patch
memory-failure-remove-calls-to-page_mapping.patch
migrate-expand-the-use-of-folio-in-__migrate_device_pages.patch
userfault-expand-folio-use-in-mfill_atomic_install_pte.patch
mm-remove-page_mapping.patch
mm-remove-page_cache_alloc.patch
mm-remove-put_devmap_managed_page.patch
mm-convert-put_devmap_managed_page_refs-to-put_devmap_managed_folio_refs.patch
mm-remove-page_ref_sub_return.patch
gup-use-folios-for-gup_devmap.patch
mm-add-kernel-doc-for-folio_mark_accessed.patch
mm-remove-pagereferenced.patch
mm-simplify-thp_vma_allowable_order.patch
mm-assert-the-mmap_lock-is-held-in-__anon_vma_prepare.patch
mm-delay-the-check-for-a-null-anon_vma.patch
mm-fix-some-minor-per-vma-lock-issues-in-userfaultfd.patch
mm-optimise-vmf_anon_prepare-for-vmas-without-an-anon_vma.patch
