The patch titled
Subject: mm/mmap: change munmap to use vma_munmap_struct() for accounting and surrounding vmas
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-change-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas.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-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas.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/mmap: change munmap to use vma_munmap_struct() for accounting and surrounding vmas
Date: Tue, 11 Jun 2024 14:01:58 -0400
Clean up the code by changing the munmap operation to use a structure for
the accounting and munmap variables.
Since remove_mt() is only called in one location and the contents will be
reduce to almost nothing. The remains of the function can be added to
vms_complete_munmap_vmas().
Link: https://lkml.kernel.org/r/20240611180200.711239-7-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/internal.h | 6 +++
mm/mmap.c | 88 ++++++++++++++++++++++++++----------------------
2 files changed, 54 insertions(+), 40 deletions(-)
--- a/mm/internal.h~mm-mmap-change-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas
+++ a/mm/internal.h
@@ -1477,12 +1477,18 @@ struct vma_munmap_struct {
struct vma_iterator *vmi;
struct mm_struct *mm;
struct vm_area_struct *vma; /* The first vma to munmap */
+ struct vm_area_struct *next; /* vma after the munmap area */
+ struct vm_area_struct *prev; /* vma before the munmap area */
struct list_head *uf; /* Userfaultfd list_head */
unsigned long start; /* Aligned start addr */
unsigned long end; /* Aligned end addr */
int vma_count; /* Number of vmas that will be removed */
unsigned long nr_pages; /* Number of pages being removed */
unsigned long locked_vm; /* Number of locked pages */
+ unsigned long nr_accounted; /* Number of VM_ACCOUNT pages */
+ unsigned long exec_vm;
+ unsigned long stack_vm;
+ unsigned long data_vm;
bool unlock; /* Unlock after the munmap */
};
--- a/mm/mmap.c~mm-mmap-change-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas
+++ a/mm/mmap.c
@@ -523,7 +523,8 @@ static inline void init_vma_munmap(struc
vms->unlock = unlock;
vms->uf = uf;
vms->vma_count = 0;
- vms->nr_pages = vms->locked_vm = 0;
+ vms->nr_pages = vms->locked_vm = vms->nr_accounted = 0;
+ vms->exec_vm = vms->stack_vm = vms->data_vm = 0;
}
/*
@@ -2389,30 +2390,6 @@ success:
}
/*
- * Ok - we have the memory areas we should free on a maple tree so release them,
- * and do the vma updates.
- *
- * Called with the mm semaphore held.
- */
-static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
-{
- unsigned long nr_accounted = 0;
- struct vm_area_struct *vma;
-
- /* Update high watermark before we lower total_vm */
- update_hiwater_vm(mm);
- mas_for_each(mas, vma, ULONG_MAX) {
- long nrpages = vma_pages(vma);
-
- if (vma->vm_flags & VM_ACCOUNT)
- nr_accounted += nrpages;
- vm_stat_account(mm, vma->vm_flags, -nrpages);
- remove_vma(vma, false);
- }
- vm_unacct_memory(nr_accounted);
-}
-
-/*
* Get rid of page table information in the indicated region.
*
* Called with the mm semaphore held.
@@ -2630,16 +2607,20 @@ static inline void abort_munmap_vmas(str
__mt_destroy(mas_detach->tree);
}
+static inline void vms_vm_stat_account(struct vma_munmap_struct *vms);
/*
* vms_complete_munmap_vmas() - Finish the munmap() operation
* @vms: The vma munmap struct
* @mas_detach: The maple state of the detached vmas
+ *
+ * This function updates the mm_struct, unmaps the region, frees the resources
+ * used for the munmap() and may downgrade the lock - if requested. Everything
+ * needed to be done once the vma maple tree is updated.
*/
-
static void vms_complete_munmap_vmas(struct vma_munmap_struct *vms,
struct ma_state *mas_detach)
{
- struct vm_area_struct *prev, *next;
+ struct vm_area_struct *vma;
struct mm_struct *mm;
mm = vms->mm;
@@ -2648,21 +2629,21 @@ static void vms_complete_munmap_vmas(str
if (vms->unlock)
mmap_write_downgrade(mm);
- prev = vma_iter_prev_range(vms->vmi);
- next = vma_next(vms->vmi);
- if (next)
- vma_iter_prev_range(vms->vmi);
-
/*
* We can free page tables without write-locking mmap_lock because VMAs
* were isolated before we downgraded mmap_lock.
*/
mas_set(mas_detach, 1);
- unmap_region(mm, mas_detach, vms->vma, prev, next, vms->start, vms->end,
- vms->vma_count, !vms->unlock);
- /* Statistics and freeing VMAs */
+ unmap_region(mm, mas_detach, vms->vma, vms->prev, vms->next,
+ vms->start, vms->end, vms->vma_count, !vms->unlock);
+ /* Update high watermark before we lower total_vm */
+ update_hiwater_vm(mm);
+ vms_vm_stat_account(vms);
mas_set(mas_detach, 0);
- remove_mt(mm, mas_detach);
+ mas_for_each(mas_detach, vma, ULONG_MAX)
+ remove_vma(vma, false);
+
+ vm_unacct_memory(vms->nr_accounted);
validate_mm(mm);
if (vms->unlock)
mmap_read_unlock(mm);
@@ -2710,13 +2691,14 @@ static int vms_gather_munmap_vmas(struct
if (error)
goto start_split_failed;
}
+ vms->prev = vma_prev(vms->vmi);
/*
* Detach a range of VMAs from the mm. Using next as a temp variable as
* it is always overwritten.
*/
- next = vms->vma;
- do {
+ for_each_vma_range(*(vms->vmi), next, vms->end) {
+ long nrpages;
/* Does it split the end? */
if (next->vm_end > vms->end) {
error = __split_vma(vms->vmi, next, vms->end, 0);
@@ -2725,8 +2707,21 @@ static int vms_gather_munmap_vmas(struct
}
vma_start_write(next);
mas_set(mas_detach, vms->vma_count++);
+ nrpages = vma_pages(next);
+
+ vms->nr_pages += nrpages;
if (next->vm_flags & VM_LOCKED)
- vms->locked_vm += vma_pages(next);
+ vms->locked_vm += nrpages;
+
+ if (next->vm_flags & VM_ACCOUNT)
+ vms->nr_accounted += nrpages;
+
+ if (is_exec_mapping(next->vm_flags))
+ vms->exec_vm += nrpages;
+ else if (is_stack_mapping(next->vm_flags))
+ vms->stack_vm += nrpages;
+ else if (is_data_mapping(next->vm_flags))
+ vms->data_vm += nrpages;
error = mas_store_gfp(mas_detach, next, GFP_KERNEL);
if (error)
@@ -2752,7 +2747,9 @@ static int vms_gather_munmap_vmas(struct
BUG_ON(next->vm_start < vms->start);
BUG_ON(next->vm_start > vms->end);
#endif
- } for_each_vma_range(*(vms->vmi), next, vms->end);
+ }
+
+ vms->next = vma_next(vms->vmi);
#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
/* Make sure no VMAs are about to be lost. */
@@ -3673,6 +3670,17 @@ void vm_stat_account(struct mm_struct *m
mm->data_vm += npages;
}
+/* Accounting for munmap */
+static inline void vms_vm_stat_account(struct vma_munmap_struct *vms)
+{
+ struct mm_struct *mm = vms->mm;
+
+ WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm) - vms->nr_pages);
+ mm->exec_vm -= vms->exec_vm;
+ mm->stack_vm -= vms->stack_vm;
+ mm->data_vm -= vms->data_vm;
+}
+
static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
/*
_
Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are
mm-mmap-correctly-position-vma_iterator-in-__split_vma.patch
mm-mmap-introduce-abort_munmap_vmas.patch
mm-mmap-introduce-vmi_complete_munmap_vmas.patch
mm-mmap-extract-the-gathering-of-vmas-from-do_vmi_align_munmap.patch
mm-mmap-introduce-vma_munmap_struct-for-use-in-munmap-operations.patch
mm-mmap-change-munmap-to-use-vma_munmap_struct-for-accounting-and-surrounding-vmas.patch
mm-mmap-extract-validate_mm-from-vma_complete.patch
mm-mmap-use-split-munmap-calls-for-map_fixed.patch
