The patch titled
Subject: mm: move may_expand_vm() check in mmap_region()
has been added to the -mm mm-unstable branch. Its filename is
mm-move-may_expand_vm-check-in-mmap_region.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-move-may_expand_vm-check-in-mmap_region.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 R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Subject: mm: move may_expand_vm() check in mmap_region()
Date: Thu, 22 Aug 2024 15:25:41 -0400
The may_expand_vm() check requires the count of the pages within the
munmap range. Since this is needed for accounting and obtained later, the
reodering of ma_expand_vm() to later in the call stack, after the vma
munmap struct (vms) is initialised and the gather stage is potentially
run, will allow for a single loop over the vmas. The gather sage does not
commit any work and so everything can be undone in the case of a failure.
The MAP_FIXED page count is available after the vms_gather_munmap_vmas()
call, so use it instead of looping over the vmas twice.
Link: https://lkml.kernel.org/r/20240822192543.3359552-20-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Bert Karwatzki <spasswolf@xxxxxx>
Cc: Jiri Olsa <olsajiri@xxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 15 ++++-----------
mm/vma.c | 21 ---------------------
mm/vma.h | 3 ---
3 files changed, 4 insertions(+), 35 deletions(-)
--- a/mm/mmap.c~mm-move-may_expand_vm-check-in-mmap_region
+++ a/mm/mmap.c
@@ -1376,17 +1376,6 @@ unsigned long mmap_region(struct file *f
pgoff_t vm_pgoff;
int error = -ENOMEM;
VMA_ITERATOR(vmi, mm, addr);
- unsigned long nr_pages, nr_accounted;
-
- nr_pages = count_vma_pages_range(mm, addr, end, &nr_accounted);
-
- /*
- * Check against address space limit.
- * MAP_FIXED may remove pages of mappings that intersects with requested
- * mapping. Account for the pages it would unmap.
- */
- if (!may_expand_vm(mm, vm_flags, pglen - nr_pages))
- return -ENOMEM;
/* Find the first overlapping VMA */
vma = vma_find(&vmi, end);
@@ -1409,6 +1398,10 @@ unsigned long mmap_region(struct file *f
vma_iter_next_range(&vmi);
}
+ /* Check against address space limit. */
+ if (!may_expand_vm(mm, vm_flags, pglen - vms.nr_pages))
+ goto abort_munmap;
+
/*
* Private writable mapping: check memory availability
*/
--- a/mm/vma.c~mm-move-may_expand_vm-check-in-mmap_region
+++ a/mm/vma.c
@@ -1645,27 +1645,6 @@ bool vma_wants_writenotify(struct vm_are
return vma_fs_can_writeback(vma);
}
-unsigned long count_vma_pages_range(struct mm_struct *mm,
- unsigned long addr, unsigned long end,
- unsigned long *nr_accounted)
-{
- VMA_ITERATOR(vmi, mm, addr);
- struct vm_area_struct *vma;
- unsigned long nr_pages = 0;
-
- *nr_accounted = 0;
- for_each_vma_range(vmi, vma, end) {
- unsigned long vm_start = max(addr, vma->vm_start);
- unsigned long vm_end = min(end, vma->vm_end);
-
- nr_pages += PHYS_PFN(vm_end - vm_start);
- if (vma->vm_flags & VM_ACCOUNT)
- *nr_accounted += PHYS_PFN(vm_end - vm_start);
- }
-
- return nr_pages;
-}
-
static DEFINE_MUTEX(mm_all_locks_mutex);
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
--- a/mm/vma.h~mm-move-may_expand_vm-check-in-mmap_region
+++ a/mm/vma.h
@@ -315,9 +315,6 @@ bool vma_wants_writenotify(struct vm_are
int mm_take_all_locks(struct mm_struct *mm);
void mm_drop_all_locks(struct mm_struct *mm);
-unsigned long count_vma_pages_range(struct mm_struct *mm,
- unsigned long addr, unsigned long end,
- unsigned long *nr_accounted);
static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma)
{
_
Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are
maple_tree-remove-rcu_read_lock-from-mt_validate.patch
mm-vma-correctly-position-vma_iterator-in-__split_vma.patch
mm-vma-introduce-abort_munmap_vmas.patch
mm-vma-introduce-vmi_complete_munmap_vmas.patch
mm-vma-extract-the-gathering-of-vmas-from-do_vmi_align_munmap.patch
mm-vma-introduce-vma_munmap_struct-for-use-in-munmap-operations.patch
mm-vma-change-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas.patch
mm-vma-change-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas-fix.patch
mm-vma-extract-validate_mm-from-vma_complete.patch
mm-vma-inline-munmap-operation-in-mmap_region.patch
mm-vma-expand-mmap_region-munmap-call.patch
mm-vma-support-vma-==-null-in-init_vma_munmap.patch
mm-mmap-reposition-vma-iterator-in-mmap_region.patch
mm-vma-track-start-and-end-for-munmap-in-vma_munmap_struct.patch
mm-clean-up-unmap_region-argument-list.patch
mm-mmap-avoid-zeroing-vma-tree-in-mmap_region.patch
mm-change-failure-of-map_fixed-to-restoring-the-gap-on-failure.patch
mm-mmap-use-phys_pfn-in-mmap_region.patch
mm-mmap-use-vms-accounted-pages-in-mmap_region.patch
ipc-shm-mm-drop-do_vma_munmap.patch
mm-move-may_expand_vm-check-in-mmap_region.patch
mm-vma-drop-incorrect-comment-from-vms_gather_munmap_vmas.patch
mm-vmah-optimise-vma_munmap_struct.patch
