The patch titled
Subject: mm/mmap: don't use __vma_adjust() in shift_arg_pages()
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Subject: mm/mmap: don't use __vma_adjust() in shift_arg_pages()
Date: Fri, 20 Jan 2023 11:26:46 -0500
Introduce shrink_vma() which uses the vma_prepare() and vma_complete()
functions to reduce the vma coverage.
Convert shift_arg_pages() to use expand_vma() and the new shrink_vma()
function. Remove support from __vma_adjust() to reduce a vma size since
shift_arg_pages() is the only user that shrinks a VMA in this way.
Link: https://lkml.kernel.org/r/20230120162650.984577-46-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/fs/exec.c~mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages
+++ a/fs/exec.c
@@ -699,7 +699,7 @@ static int shift_arg_pages(struct vm_are
/*
* cover the whole range: [new_start, old_end)
*/
- if (vma_adjust(&vmi, vma, new_start, old_end, vma->vm_pgoff))
+ if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
return -ENOMEM;
/*
@@ -733,7 +733,7 @@ static int shift_arg_pages(struct vm_are
vma_prev(&vmi);
/* Shrink the vma to just the new range */
- return vma_adjust(&vmi, vma, new_start, new_end, vma->vm_pgoff);
+ return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
}
/*
--- a/include/linux/mm.h~mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages
+++ a/include/linux/mm.h
@@ -2831,17 +2831,11 @@ void anon_vma_interval_tree_verify(struc
/* mmap.c */
extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
-extern int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, unsigned long start,
- unsigned long end, pgoff_t pgoff, struct vm_area_struct *expand);
-static inline int vma_adjust(struct vma_iterator *vmi,
- struct vm_area_struct *vma, unsigned long start, unsigned long end,
- pgoff_t pgoff)
-{
- return __vma_adjust(vmi, vma, start, end, pgoff, NULL);
-}
extern int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long start, unsigned long end, pgoff_t pgoff,
struct vm_area_struct *next);
+extern int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, pgoff_t pgoff);
extern struct vm_area_struct *vma_merge(struct vma_iterator *vmi,
struct mm_struct *, struct vm_area_struct *prev, unsigned long addr,
unsigned long end, unsigned long vm_flags, struct anon_vma *,
--- a/mm/mmap.c~mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages
+++ a/mm/mmap.c
@@ -685,6 +685,44 @@ int vma_expand(struct vma_iterator *vmi,
nomem:
return -ENOMEM;
}
+
+/*
+ * vma_shrink() - Reduce an existing VMAs memory area
+ * @vmi: The vma iterator
+ * @vma: The VMA to modify
+ * @start: The new start
+ * @end: The new end
+ *
+ * Returns: 0 on success, -ENOMEM otherwise
+ */
+int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, pgoff_t pgoff)
+{
+ struct vma_prepare vp;
+
+ WARN_ON((vma->vm_start != start) && (vma->vm_end != end));
+
+ if (vma_iter_prealloc(vmi))
+ return -ENOMEM;
+
+ init_vma_prep(&vp, vma);
+ vma_adjust_trans_huge(vma, start, end, 0);
+ vma_prepare(&vp);
+
+ if (vma->vm_start < start)
+ vma_iter_clear(vmi, vma->vm_start, start);
+
+ if (vma->vm_end > end)
+ vma_iter_clear(vmi, end, vma->vm_end);
+
+ vma->vm_start = start;
+ vma->vm_end = end;
+ vma->vm_pgoff = pgoff;
+ vma_complete(&vp, vmi, vma->vm_mm);
+ validate_mm(vma->vm_mm);
+ return 0;
+}
+
/*
* We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
* is already present in an i_mmap tree without adjusting the tree.
@@ -800,14 +838,7 @@ int __vma_adjust(struct vma_iterator *vm
vma_prepare(&vma_prep);
- if (vma->vm_start < start)
- vma_iter_clear(vmi, vma->vm_start, start);
- else if (start != vma->vm_start)
- vma_changed = true;
-
- if (vma->vm_end > end)
- vma_iter_clear(vmi, end, vma->vm_end);
- else if (end != vma->vm_end)
+ if (start < vma->vm_start || end > vma->vm_end)
vma_changed = true;
vma->vm_start = start;
@@ -820,7 +851,10 @@ int __vma_adjust(struct vma_iterator *vm
if (adjust_next) {
next->vm_start += adjust_next;
next->vm_pgoff += adjust_next >> PAGE_SHIFT;
- vma_iter_store(vmi, next);
+ if (adjust_next < 0) {
+ WARN_ON_ONCE(vma_changed);
+ vma_iter_store(vmi, next);
+ }
}
vma_complete(&vma_prep, vmi, mm);
_
Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are
maple_tree-add-mas_init-function.patch
maple_tree-fix-potential-rcu-issue.patch
maple_tree-reduce-user-error-potential.patch
test_maple_tree-test-modifications-while-iterating.patch
mm-expand-vma-iterator-interface.patch
mm-mmap-convert-brk-to-use-vma-iterator.patch
kernel-fork-convert-forking-to-using-the-vmi-iterator.patch
mmap-convert-vma_link-vma-iterator.patch
mm-mmap-remove-preallocation-from-do_mas_align_munmap.patch
mmap-change-do_mas_munmap-and-do_mas_aligned_munmap-to-use-vma-iterator.patch
mmap-convert-vma_expand-to-use-vma-iterator.patch
mm-add-temporary-vma-iterator-versions-of-vma_merge-split_vma-and-__split_vma.patch
ipc-shm-use-the-vma-iterator-for-munmap-calls.patch
userfaultfd-use-vma-iterator.patch
mm-change-mprotect_fixup-to-vma-iterator.patch
mlock-convert-mlock-to-vma-iterator.patch
coredump-convert-to-vma-iterator.patch
mempolicy-convert-to-vma-iterator.patch
task_mmu-convert-to-vma-iterator.patch
sched-convert-to-vma-iterator.patch
madvise-use-vmi-iterator-for-__split_vma-and-vma_merge.patch
mmap-pass-through-vmi-iterator-to-__split_vma.patch
mmap-use-vmi-version-of-vma_merge.patch
mm-mremap-use-vmi-version-of-vma_merge.patch
nommu-convert-nommu-to-using-the-vma-iterator.patch
mm-switch-vma_merge-split_vma-and-__split_vma-to-vma-iterator.patch
mmap-convert-__vma_adjust-to-use-vma-iterator.patch
mm-pass-through-vma-iterator-to-__vma_adjust.patch
madvise-use-split_vma-instead-of-__split_vma.patch
mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust.patch
mm-pass-vma-iterator-through-to-__vma_adjust.patch
mm-add-vma-iterator-to-vma_adjust-arguments.patch
mmap-clean-up-mmap_region-unrolling.patch
mm-change-munmap-splitting-order-and-move_vma.patch
mm-mmap-move-anon_vma-setting-in-__vma_adjust.patch
mm-mmap-refactor-locking-out-of-__vma_adjust.patch
mm-mmap-use-vma_prepare-and-vma_complete-in-vma_expand.patch
mm-mmap-introduce-init_vma_prep-and-init_multi_vma_prep.patch
mm-dont-use-__vma_adjust-in-__split_vma.patch
mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages.patch
mm-mmap-introduce-dup_vma_anon-helper.patch
mm-mmap-convert-do_brk_flags-to-use-vma_prepare-and-vma_complete.patch
mm-mmap-remove-__vma_adjust.patch
vma_merge-set-vma-iterator-to-correct-position.patch
