[PATCH 01/38] mm: drop support of non-linear mapping from unmap/zap codepath

Kirill A. Shutemov
2014-12-24T12:33:58Z

We don't create non-linear mappings anymore. Let's drop code which
handles them on unmap/zap.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/mm.h | 1 -
mm/madvise.c | 9 +-----
mm/memory.c | 82 ++++++++++++++----------------------------------------
3 files changed, 22 insertions(+), 70 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f80d0194c9bc..07574d8072f4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1119,7 +1119,6 @@ extern void user_shm_unlock(size_t, struct user_struct *);
* Parameter block passed down to zap_pte_range in exceptional cases.
*/
struct zap_details {
- struct vm_area_struct *nonlinear_vma; /* Check page->index if set */
struct address_space *check_mapping; /* Check page->mapping if set */
pgoff_t first_index; /* Lowest page->index to unmap */
pgoff_t last_index; /* Highest page->index to unmap */
diff --git a/mm/madvise.c b/mm/madvise.c
index 6fc9b8298da1..8d74d7617598 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -419,14 +419,7 @@ static long madvise_dontneed(struct vm_area_struct *vma,
if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
return -EINVAL;

- if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
- struct zap_details details = {
- .nonlinear_vma = vma,
- .last_index = ULONG_MAX,
- };
- zap_page_range(vma, start, end - start, &details);
- } else
- zap_page_range(vma, start, end - start, NULL);
+ zap_page_range(vma, start, end - start, NULL);
return 0;
}

diff --git a/mm/memory.c b/mm/memory.c
index 33f7370cc092..5216b91a714a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1082,6 +1082,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
spinlock_t *ptl;
pte_t *start_pte;
pte_t *pte;
+ swp_entry_t entry;

again:
init_rss_vec(rss);
@@ -1107,28 +1108,12 @@ again:
if (details->check_mapping &&
details->check_mapping != page->mapping)
continue;
- /*
- * Each page->index must be checked when
- * invalidating or truncating nonlinear.
- */
- if (details->nonlinear_vma &&
- (page->index < details->first_index ||
- page->index > details->last_index))
- continue;
}
ptent = ptep_get_and_clear_full(mm, addr, pte,
tlb->fullmm);
tlb_remove_tlb_entry(tlb, pte, addr);
if (unlikely(!page))
continue;
- if (unlikely(details) && details->nonlinear_vma
- && linear_page_index(details->nonlinear_vma,
- addr) != page->index) {
- pte_t ptfile = pgoff_to_pte(page->index);
- if (pte_soft_dirty(ptent))
- ptfile = pte_file_mksoft_dirty(ptfile);
- set_pte_at(mm, addr, pte, ptfile);
- }
if (PageAnon(page))
rss[MM_ANONPAGES]--;
else {
@@ -1151,33 +1136,25 @@ again:
}
continue;
}
- /*
- * If details->check_mapping, we leave swap entries;
- * if details->nonlinear_vma, we leave file entries.
- */
+ /* If details->check_mapping, we leave swap entries. */
if (unlikely(details))
continue;
- if (pte_file(ptent)) {
- if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
- print_bad_pte(vma, addr, ptent, NULL);
- } else {
- swp_entry_t entry = pte_to_swp_entry(ptent);

- if (!non_swap_entry(entry))
- rss[MM_SWAPENTS]--;
- else if (is_migration_entry(entry)) {
- struct page *page;
+ entry = pte_to_swp_entry(ptent);
+ if (!non_swap_entry(entry))
+ rss[MM_SWAPENTS]--;
+ else if (is_migration_entry(entry)) {
+ struct page *page;

- page = migration_entry_to_page(entry);
+ page = migration_entry_to_page(entry);

- if (PageAnon(page))
- rss[MM_ANONPAGES]--;
- else
- rss[MM_FILEPAGES]--;
- }
- if (unlikely(!free_swap_and_cache(entry)))
- print_bad_pte(vma, addr, ptent, NULL);
+ if (PageAnon(page))
+ rss[MM_ANONPAGES]--;
+ else
+ rss[MM_FILEPAGES]--;
}
+ if (unlikely(!free_swap_and_cache(entry)))
+ print_bad_pte(vma, addr, ptent, NULL);
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
} while (pte++, addr += PAGE_SIZE, addr != end);

@@ -1277,7 +1254,7 @@ static void unmap_page_range(struct mmu_gather *tlb,
pgd_t *pgd;
unsigned long next;

- if (details && !details->check_mapping && !details->nonlinear_vma)
+ if (details && !details->check_mapping)
details = NULL;

BUG_ON(addr >= end);
@@ -1371,7 +1348,7 @@ void unmap_vmas(struct mmu_gather *tlb,
* @vma: vm_area_struct holding the applicable pages
* @start: starting address of pages to zap
* @size: number of bytes to zap
- * @details: details of nonlinear truncation or shared cache invalidation
+ * @details: details of shared cache invalidation
*
* Caller must protect the VMA list
*/
@@ -1397,7 +1374,7 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start,
* @vma: vm_area_struct holding the applicable pages
* @address: starting address of pages to zap
* @size: number of bytes to zap
- * @details: details of nonlinear truncation or shared cache invalidation
+ * @details: details of shared cache invalidation
*
* The range must fit into one VMA.
*/
@@ -2324,25 +2301,11 @@ static inline void unmap_mapping_range_tree(struct rb_root *root,
}
}

-static inline void unmap_mapping_range_list(struct list_head *head,
- struct zap_details *details)
-{
- struct vm_area_struct *vma;
-
- /*
- * In nonlinear VMAs there is no correspondence between virtual address
- * offset and file offset. So we must perform an exhaustive search
- * across *all* the pages in each nonlinear VMA, not just the pages
- * whose virtual address lies outside the file truncation point.
- */
- list_for_each_entry(vma, head, shared.nonlinear) {
- details->nonlinear_vma = vma;
- unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
- }
-}
-
/**
- * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
+ * unmap_mapping_range - unmap the portion of all mmaps in the specified
+ * address_space corresponding to the specified page range in the underlying
+ * file.
+ *
* @mapping: the address space containing mmaps to be unmapped.
* @holebegin: byte in first page to unmap, relative to the start of
* the underlying file. This will be rounded down to a PAGE_SIZE
@@ -2371,7 +2334,6 @@ void unmap_mapping_range(struct address_space *mapping,
}

details.check_mapping = even_cows? NULL: mapping;
- details.nonlinear_vma = NULL;
details.first_index = hba;
details.last_index = hba + hlen - 1;
if (details.last_index < details.first_index)
@@ -2381,8 +2343,6 @@ void unmap_mapping_range(struct address_space *mapping,
i_mmap_lock_read(mapping);
if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
unmap_mapping_range_tree(&mapping->i_mmap, &details);
- if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
- unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
i_mmap_unlock_read(mapping);
}
EXPORT_SYMBOL(unmap_mapping_range);
--
2.1.3