The patch titled
Subject: mmap: remove do_brk_munmap() optimization
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-change-do_brk_flags-to-expand-existing-vma-and-add-do_brk_munmap-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-change-do_brk_flags-to-expand-existing-vma-and-add-do_brk_munmap-fix.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: Liam Howlett <liam.howlett@xxxxxxxxxx>
Subject: mmap: remove do_brk_munmap() optimization
Date: Tue, 19 Jul 2022 19:14:01 +0000
This optimization does not work with the locking.
Link: https://lkml.kernel.org/r/20220719191352.3366482-2-Liam.Howlett@xxxxxxxxxx
Fixes: f12fee814843 (mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap())
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 61 +---------------------------------------------------
1 file changed, 2 insertions(+), 59 deletions(-)
--- a/mm/mmap.c~mm-mmap-change-do_brk_flags-to-expand-existing-vma-and-add-do_brk_munmap-fix
+++ a/mm/mmap.c
@@ -2809,67 +2809,10 @@ static int do_brk_munmap(struct ma_state
struct list_head *uf)
{
struct mm_struct *mm = vma->vm_mm;
- struct vm_area_struct unmap;
- unsigned long unmap_pages;
- int ret = 1;
+ int ret;
arch_unmap(mm, newbrk, oldbrk);
-
- if (likely((vma->vm_end < oldbrk) ||
- ((vma->vm_start == newbrk) && (vma->vm_end == oldbrk)))) {
- /* remove entire mapping(s) */
- mas_set(mas, newbrk);
- if (vma->vm_start != newbrk)
- mas_reset(mas); /* cause a re-walk for the first overlap. */
- ret = __do_munmap(mm, newbrk, oldbrk - newbrk, uf, true);
- goto munmap_full_vma;
- }
-
- vma_init(&unmap, mm);
- unmap.vm_start = newbrk;
- unmap.vm_end = oldbrk;
- ret = userfaultfd_unmap_prep(&unmap, newbrk, oldbrk, uf);
- if (ret)
- return ret;
- ret = 1;
-
- /* Change the oldbrk of vma to the newbrk of the munmap area */
- vma_adjust_trans_huge(vma, vma->vm_start, newbrk, 0);
- if (mas_preallocate(mas, vma, GFP_KERNEL))
- return -ENOMEM;
-
- if (vma->anon_vma) {
- anon_vma_lock_write(vma->anon_vma);
- anon_vma_interval_tree_pre_update_vma(vma);
- }
-
- vma->vm_end = newbrk;
- vma_init(&unmap, mm);
- unmap.vm_start = newbrk;
- unmap.vm_end = oldbrk;
- if (vma->anon_vma)
- vma_set_anonymous(&unmap);
-
- vma_mas_remove(&unmap, mas);
-
- vmacache_invalidate(vma->vm_mm);
- if (vma->anon_vma) {
- anon_vma_interval_tree_post_update_vma(vma);
- anon_vma_unlock_write(vma->anon_vma);
- }
-
- unmap_pages = vma_pages(&unmap);
- if (vma->vm_flags & VM_LOCKED)
- mm->locked_vm -= unmap_pages;
-
- mmap_write_downgrade(mm);
- unmap_region(mm, &unmap, vma, newbrk, oldbrk);
- /* Statistics */
- vm_stat_account(mm, vma->vm_flags, -unmap_pages);
- if (vma->vm_flags & VM_ACCOUNT)
- vm_unacct_memory(unmap_pages);
-
-munmap_full_vma:
+ ret = __do_munmap(mm, newbrk, oldbrk - newbrk, uf, true);
validate_mm_mt(mm);
return ret;
}
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
android-binder-fix-lockdep-check-on-clearing-vma.patch
maple-tree-add-new-data-structure-fix.patch
maple-tree-add-new-data-structure-fix-2.patch
mm-start-tracking-vmas-with-maple-tree-fix.patch
mm-mmap-use-maple-tree-for-unmapped_area_topdown-fix.patch
mm-mmap-change-do_brk_flags-to-expand-existing-vma-and-add-do_brk_munmap-fix.patch
mm-mmap-use-advanced-maple-tree-api-for-mmap_region-fix.patch
mm-mlock-drop-dead-code-in-count_mm_mlocked_page_nr.patch
