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mm: abstract vma_expand() to use vma_merge_struct

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The purpose of the vmg is to thread merge state through functions and
avoid egregious parameter lists.  We expand this to vma_expand(), which is
used for a number of merge cases.

Accordingly, adjust its callers, mmap_region() and relocate_vma_down(), to
use a vmg.

An added purpose of this change is the ability in a future commit to
perform all new VMA range merging using vma_expand().

Link: https://lkml.kernel.org/r/4bc8c9dbc9ca52452ef8e587b28fe555854ceb38.1725040657.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2024-08-30 19:10:17 +01:00 committed by Andrew Morton
parent 3e01310d29
commit fc21959f74
4 changed files with 27 additions and 35 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
mm/mmap.c
View file

@ -1371,7 +1371,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
struct ma_state mas_detach;
struct maple_tree mt_detach;
unsigned long end = addr + len;
unsigned long merge_start = addr, merge_end = end;
bool writable_file_mapping = false;
int error = -ENOMEM;
VMA_ITERATOR(vmi, mm, addr);
@ -1424,8 +1423,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
/* Attempt to expand an old mapping */
/* Check next */
if (next && next->vm_start == end && can_vma_merge_before(&vmg)) {
merge_end = next->vm_end;
vma = next;
vmg.end = next->vm_end;
vma = vmg.vma = next;
vmg.pgoff = next->vm_pgoff - pglen;
/*
* We set this here so if we will merge with the previous VMA in
@ -1438,15 +1437,15 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
/* Check prev */
if (prev && prev->vm_end == addr && can_vma_merge_after(&vmg)) {
merge_start = prev->vm_start;
vma = prev;
vmg.start = prev->vm_start;
vma = vmg.vma = prev;
vmg.pgoff = prev->vm_pgoff;
vma_prev(&vmi); /* Equivalent to going to the previous range */
}
if (vma) {
/* Actually expand, if possible */
if (!vma_expand(&vmi, vma, merge_start, merge_end, vmg.pgoff, next)) {
if (!vma_expand(&vmg)) {
khugepaged_enter_vma(vma, vm_flags);
goto expanded;
}
@ -2320,6 +2319,7 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift)
unsigned long new_start = old_start - shift;
unsigned long new_end = old_end - shift;
VMA_ITERATOR(vmi, mm, new_start);
VMG_STATE(vmg, mm, &vmi, new_start, old_end, 0, vma->vm_pgoff);
struct vm_area_struct *next;
struct mmu_gather tlb;
@ -2336,7 +2336,8 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift)
/*
* cover the whole range: [new_start, old_end)
*/
if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
vmg.vma = vma;
if (vma_expand(&vmg))
return -ENOMEM;
/*

39
mm/vma.c
View file

@ -467,30 +467,25 @@ void validate_mm(struct mm_struct *mm)
/*
* vma_expand - Expand an existing VMA
*
* @vmi: The vma iterator
* @vma: The vma to expand
* @start: The start of the vma
* @end: The exclusive end of the vma
* @pgoff: The page offset of vma
* @next: The current of next vma.
* @vmg: Describes a VMA expansion operation.
*
* Expand @vma to @start and @end. Can expand off the start and end. Will
* expand over @next if it's different from @vma and @end == @next->vm_end.
* Checking if the @vma can expand and merge with @next needs to be handled by
* the caller.
* Expand @vma to vmg->start and vmg->end. Can expand off the start and end.
* Will expand over vmg->next if it's different from vmg->vma and vmg->end ==
* vmg->next->vm_end. Checking if the vmg->vma can expand and merge with
* vmg->next needs to be handled by the caller.
*
* Returns: 0 on success
*/
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)
int vma_expand(struct vma_merge_struct *vmg)
{
struct vm_area_struct *anon_dup = NULL;
bool remove_next = false;
struct vm_area_struct *vma = vmg->vma;
struct vm_area_struct *next = vmg->next;
struct vma_prepare vp;
vma_start_write(vma);
if (next && (vma != next) && (end == next->vm_end)) {
if (next && (vma != next) && (vmg->end == next->vm_end)) {
int ret;
remove_next = true;
@ -503,21 +498,21 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
/* Not merging but overwriting any part of next is not handled. */
VM_WARN_ON(next && !vp.remove &&
next != vma && end > next->vm_start);
next != vma && vmg->end > next->vm_start);
/* Only handles expanding */
VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
VM_WARN_ON(vma->vm_start < vmg->start || vma->vm_end > vmg->end);
/* Note: vma iterator must be pointing to 'start' */
vma_iter_config(vmi, start, end);
if (vma_iter_prealloc(vmi, vma))
vma_iter_config(vmg->vmi, vmg->start, vmg->end);
if (vma_iter_prealloc(vmg->vmi, vma))
goto nomem;
vma_prepare(&vp);
vma_adjust_trans_huge(vma, start, end, 0);
vma_set_range(vma, start, end, pgoff);
vma_iter_store(vmi, vma);
vma_adjust_trans_huge(vma, vmg->start, vmg->end, 0);
vma_set_range(vma, vmg->start, vmg->end, vmg->pgoff);
vma_iter_store(vmg->vmi, vma);
vma_complete(&vp, vmi, vma->vm_mm);
vma_complete(&vp, vmg->vmi, vma->vm_mm);
return 0;
nomem:

5
mm/vma.h
View file

@ -128,10 +128,7 @@ void init_vma_prep(struct vma_prepare *vp,
void vma_complete(struct vma_prepare *vp,
struct vma_iterator *vmi, struct mm_struct *mm);
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);
int vma_expand(struct vma_merge_struct *vmg);
int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
unsigned long start, unsigned long end, pgoff_t pgoff);

3
tools/testing/vma/vma.c
View file

@ -121,8 +121,7 @@ static struct vm_area_struct *merge_existing(struct vma_merge_struct *vmg)
*/
static int expand_existing(struct vma_merge_struct *vmg)
{
return vma_expand(vmg->vmi, vmg->vma, vmg->start, vmg->end, vmg->pgoff,
vmg->next);
return vma_expand(vmg);
}
/*