The patch titled
Subject: mm: always lock new vma before inserting into vma tree
has been added to the -mm mm-unstable branch. Its filename is
mm-always-lock-new-vma-before-inserting-into-vma-tree.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-always-lock-new-vma-before-inserting-into-vma-tree.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: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: mm: always lock new vma before inserting into vma tree
Date: Fri, 4 Aug 2023 08:27:23 -0700
While it's not strictly necessary to lock a newly created vma before
adding it into the vma tree (as long as no further changes are performed
to it), it seems like a good policy to lock it and prevent accidental
changes after it becomes visible to the page faults. Lock the vma before
adding it into the vma tree.
Link: https://lkml.kernel.org/r/20230804152724.3090321-6-surenb@xxxxxxxxxx
Suggested-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/mm/mmap.c~mm-always-lock-new-vma-before-inserting-into-vma-tree
+++ a/mm/mmap.c
@@ -403,6 +403,8 @@ static int vma_link(struct mm_struct *mm
vma_iter_store(&vmi, vma);
+ vma_start_write(vma);
+
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
i_mmap_lock_write(mapping);
@@ -463,7 +465,8 @@ static inline void vma_prepare(struct vm
vma_start_write(vp->vma);
if (vp->adj_next)
vma_start_write(vp->adj_next);
- /* vp->insert is always a newly created VMA, no need for locking */
+ if (vp->insert)
+ vma_start_write(vp->insert);
if (vp->remove)
vma_start_write(vp->remove);
if (vp->remove2)
@@ -3093,6 +3096,7 @@ static int do_brk_flags(struct vma_itera
vma->vm_pgoff = addr >> PAGE_SHIFT;
vm_flags_init(vma, flags);
vma->vm_page_prot = vm_get_page_prot(flags);
+ vma_start_write(vma);
if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
goto mas_store_fail;
@@ -3341,7 +3345,6 @@ struct vm_area_struct *copy_vma(struct v
get_file(new_vma->vm_file);
if (new_vma->vm_ops && new_vma->vm_ops->open)
new_vma->vm_ops->open(new_vma);
- vma_start_write(new_vma);
if (vma_link(mm, new_vma))
goto out_vma_link;
*need_rmap_locks = false;
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
mm-enable-page-walking-api-to-lock-vmas-during-the-walk.patch
swap-remove-remnants-of-polling-from-read_swap_cache_async.patch
mm-add-missing-vm_fault_result_trace-name-for-vm_fault_completed.patch
mm-drop-per-vma-lock-when-returning-vm_fault_retry-or-vm_fault_completed.patch
mm-change-folio_lock_or_retry-to-use-vm_fault-directly.patch
mm-handle-swap-page-faults-under-per-vma-lock.patch
mm-handle-userfaults-under-vma-lock.patch
mm-handle-userfaults-under-vma-lock-fix.patch
mm-for-config_per_vma_lock-equate-write-lock-assertion-for-vma-and-mmap.patch
mm-replace-mmap-with-vma-write-lock-assertions-when-operating-on-a-vma.patch
mm-lock-vma-explicitly-before-doing-vm_flags_reset-and-vm_flags_reset_once.patch
mm-always-lock-new-vma-before-inserting-into-vma-tree.patch
mm-move-vma-locking-out-of-vma_prepare-and-dup_anon_vma.patch
