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FROMLIST: BACKPORT: mm: Change do_vmi_align_munmap() side tree index

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The majority of the calls to munmap a VMA is for a single vma.  The
maple tree is able to store a single entry at 0, with a size of 1 as a
pointer and avoid any allocations.  Change do_vmi_align_munmap() to
store the VMAs being munmap()'ed into a tree indexed by the count.  This
will leverage the ability to store the first entry without a node
allocation.

Storing the entries into a tree by the count and not the vma start and
end means changing the functions which iterate over the entries.  Update
unmap_vmas() and free_pgtables() to take a maple state and a tree end
address to support this functionality.

Passing through the same maple state to unmap_vmas() and free_pgtables()
means the state needs to be reset between calls.  This happens in the
static unmap_region() and exit_mmap().

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>

Link: https://lore.kernel.org/lkml/20230601021605.2823123-5-Liam.Howlett@oracle.com/
[surenb: skip changes passing maple state to unmap_vmas() and
free_pgtables()]

Bug: 274059236
Change-Id: If38cfecd51da884bcfdbdfdfbf955a0b338d3d60
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Liam R. Howlett 2023-04-28 05:11:36 -04:00 • committed by Suren Baghdasaryan
parent 25bed2fdbc
commit e9fdabfc2a
4 changed files with 32 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

3
include/linux/mm.h
View file

@ -1904,7 +1904,8 @@ void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *details);
void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
struct vm_area_struct *start_vma, unsigned long start,
unsigned long end);
unsigned long end, unsigned long start_t,
unsigned long end_t);
struct mmu_notifier_range;

2
mm/internal.h
View file

@ -87,7 +87,7 @@ void folio_activate(struct folio *folio);
void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
struct vm_area_struct *start_vma, unsigned long floor,
unsigned long ceiling);
unsigned long ceiling, unsigned long start_t);
void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte);
struct zap_details;

11
mm/memory.c
View file

@ -397,9 +397,9 @@ void free_pgd_range(struct mmu_gather *tlb,
void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
struct vm_area_struct *vma, unsigned long floor,
unsigned long ceiling)
unsigned long ceiling, unsigned long start_t)
{
MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
MA_STATE(mas, mt, start_t, start_t);
do {
unsigned long addr = vma->vm_start;
@ -1704,7 +1704,8 @@ static void unmap_single_vma(struct mmu_gather *tlb,
*/
void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr)
unsigned long end_addr, unsigned long start_t,
unsigned long end_t)
{
struct mmu_notifier_range range;
struct zap_details details = {
@ -1712,14 +1713,14 @@ void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
/* Careful - we need to zap private pages too! */
.even_cows = true,
};
MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
MA_STATE(mas, mt, start_t, start_t);
mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
start_addr, end_addr);
mmu_notifier_invalidate_range_start(&range);
do {
unmap_single_vma(tlb, vma, start_addr, end_addr, &details);
} while ((vma = mas_find(&mas, end_addr - 1)) != NULL);
} while ((vma = mas_find(&mas, end_t - 1)) != NULL);
mmu_notifier_invalidate_range_end(&range);
}

40
mm/mmap.c
View file

@ -80,7 +80,7 @@ core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
struct vm_area_struct *vma, struct vm_area_struct *prev,
struct vm_area_struct *next, unsigned long start,
unsigned long end);
unsigned long end, unsigned long start_t, unsigned long end_t);
static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
{
@ -2180,17 +2180,17 @@ static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
*/
static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
struct vm_area_struct *vma, struct vm_area_struct *prev,
struct vm_area_struct *next,
unsigned long start, unsigned long end)
struct vm_area_struct *next, unsigned long start,
unsigned long end, unsigned long start_t, unsigned long end_t)
{
struct mmu_gather tlb;
lru_add_drain();
tlb_gather_mmu(&tlb, mm);
update_hiwater_rss(mm);
unmap_vmas(&tlb, mt, vma, start, end);
unmap_vmas(&tlb, mt, vma, start, end, start_t, end_t);
free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
next ? next->vm_start : USER_PGTABLES_CEILING);
next ? next->vm_start : USER_PGTABLES_CEILING, start_t);
tlb_finish_mmu(&tlb);
}
@ -2276,10 +2276,10 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
return __split_vma(mm, vma, addr, new_below);
}
static inline int munmap_sidetree(struct vm_area_struct *vma,
static inline int munmap_sidetree(struct vm_area_struct *vma, int count,
struct ma_state *mas_detach)
{
mas_set_range(mas_detach, vma->vm_start, vma->vm_end - 1);
mas_set(mas_detach, count);
if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
return -ENOMEM;
@ -2365,7 +2365,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
mas_set(mas, end);
split = mas_prev(mas, 0);
error = munmap_sidetree(split, &mas_detach);
error = munmap_sidetree(split, count, &mas_detach);
if (error)
goto munmap_sidetree_failed;
@ -2374,7 +2374,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
vma = split;
break;
}
error = munmap_sidetree(next, &mas_detach);
error = munmap_sidetree(next, count, &mas_detach);
if (error)
goto munmap_sidetree_failed;
@ -2407,17 +2407,22 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
/* Make sure no VMAs are about to be lost. */
{
MA_STATE(test, &mt_detach, start, end - 1);
MA_STATE(test, &mt_detach, 0, 0);
struct vm_area_struct *vma_mas, *vma_test;
int test_count = 0;
unsigned long s, e;
mas_set_range(mas, start, end - 1);
rcu_read_lock();
vma_test = mas_find(&test, end - 1);
vma_test = mas_find(&test, count - 1);
mas_for_each(mas, vma_mas, end - 1) {
if (!test_count)
s = vma_mas->vm_start;
BUG_ON(vma_mas != vma_test);
test_count++;
vma_test = mas_next(&test, end - 1);
if (test_count == count)
e = vma_mas->vm_end;
vma_test = mas_next(&test, count - 1);
}
rcu_read_unlock();
BUG_ON(count != test_count);
@ -2443,9 +2448,9 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
mmap_write_downgrade(mm);
}
unmap_region(mm, &mt_detach, vma, prev, next, start, end);
unmap_region(mm, &mt_detach, vma, prev, next, start, end, 1, count);
/* Statistics and freeing VMAs */
mas_set(&mas_detach, start);
mas_set(&mas_detach, 0);
remove_mt(mm, &mas_detach);
__mt_destroy(&mt_detach);
@ -2757,7 +2762,8 @@ unmap_and_free_vma:
vma->vm_file = NULL;
/* Undo any partial mapping done by a device driver. */
unmap_region(mm, mas.tree, vma, prev, next, vma->vm_start, vma->vm_end);
unmap_region(mm, mas.tree, vma, prev, next, vma->vm_start, vma->vm_end,
vma->vm_end, vma->vm_end);
if (file && (vm_flags & VM_SHARED))
mapping_unmap_writable(file->f_mapping);
free_vma:
@ -3090,7 +3096,7 @@ void exit_mmap(struct mm_struct *mm)
tlb_gather_mmu_fullmm(&tlb, mm);
/* update_hiwater_rss(mm) here? but nobody should be looking */
/* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX);
unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX, vma->vm_end, ULONG_MAX);
mmap_read_unlock(mm);
/*
@ -3101,7 +3107,7 @@ void exit_mmap(struct mm_struct *mm)
mmap_write_lock(mm);
mt_clear_in_rcu(&mm->mm_mt);
free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS,
USER_PGTABLES_CEILING);
USER_PGTABLES_CEILING, vma->vm_end);
tlb_finish_mmu(&tlb);
/*