Nobody creates nonlinear VMAs. No need to support them.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
include/linux/rmap.h | 2 -
mm/migrate.c | 32 --------
mm/rmap.c | 216 ---------------------------------------------------
3 files changed, 250 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 9be55c7617da..812774417407 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -237,7 +237,6 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
* arg: passed to rmap_one() and invalid_vma()
* rmap_one: executed on each vma where page is mapped
* done: for checking traversing termination condition
- * file_nonlinear: for handling file nonlinear mapping
* anon_lock: for getting anon_lock by optimized way rather than default
* invalid_vma: for skipping uninterested vma
*/
@@ -246,7 +245,6 @@ struct rmap_walk_control {
int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
unsigned long addr, void *arg);
int (*done)(struct page *page);
- int (*file_nonlinear)(struct page *, struct address_space *, void *arg);
struct anon_vma *(*anon_lock)(struct page *page);
bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
};
diff --git a/mm/migrate.c b/mm/migrate.c
index bed48809e5d0..b494fdb9a636 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -178,37 +178,6 @@ out:
}
/*
- * Congratulations to trinity for discovering this bug.
- * mm/fremap.c's remap_file_pages() accepts any range within a single vma to
- * convert that vma to VM_NONLINEAR; and generic_file_remap_pages() will then
- * replace the specified range by file ptes throughout (maybe populated after).
- * If page migration finds a page within that range, while it's still located
- * by vma_interval_tree rather than lost to i_mmap_nonlinear list, no problem:
- * zap_pte() clears the temporary migration entry before mmap_sem is dropped.
- * But if the migrating page is in a part of the vma outside the range to be
- * remapped, then it will not be cleared, and remove_migration_ptes() needs to
- * deal with it. Fortunately, this part of the vma is of course still linear,
- * so we just need to use linear location on the nonlinear list.
- */
-static int remove_linear_migration_ptes_from_nonlinear(struct page *page,
- struct address_space *mapping, void *arg)
-{
- struct vm_area_struct *vma;
- /* hugetlbfs does not support remap_pages, so no huge pgoff worries */
- pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- unsigned long addr;
-
- list_for_each_entry(vma,
- &mapping->i_mmap_nonlinear, shared.nonlinear) {
-
- addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
- if (addr >= vma->vm_start && addr < vma->vm_end)
- remove_migration_pte(page, vma, addr, arg);
- }
- return SWAP_AGAIN;
-}
-
-/*
* Get rid of all migration entries and replace them by
* references to the indicated page.
*/
@@ -217,7 +186,6 @@ static void remove_migration_ptes(struct page *old, struct page *new)
struct rmap_walk_control rwc = {
.rmap_one = remove_migration_pte,
.arg = old,
- .file_nonlinear = remove_linear_migration_ptes_from_nonlinear,
};
rmap_walk(new, &rwc);
diff --git a/mm/rmap.c b/mm/rmap.c
index d8e1a7e7fbe8..e031d4ad0a4b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1252,207 +1252,6 @@ out_mlock:
return ret;
}
-/*
- * objrmap doesn't work for nonlinear VMAs because the assumption that
- * offset-into-file correlates with offset-into-virtual-addresses does not hold.
- * Consequently, given a particular page and its ->index, we cannot locate the
- * ptes which are mapping that page without an exhaustive linear search.
- *
- * So what this code does is a mini "virtual scan" of each nonlinear VMA which
- * maps the file to which the target page belongs. The ->vm_private_data field
- * holds the current cursor into that scan. Successive searches will circulate
- * around the vma's virtual address space.
- *
- * So as more replacement pressure is applied to the pages in a nonlinear VMA,
- * more scanning pressure is placed against them as well. Eventually pages
- * will become fully unmapped and are eligible for eviction.
- *
- * For very sparsely populated VMAs this is a little inefficient - chances are
- * there there won't be many ptes located within the scan cluster. In this case
- * maybe we could scan further - to the end of the pte page, perhaps.
- *
- * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
- * acquire it without blocking. If vma locked, mlock the pages in the cluster,
- * rather than unmapping them. If we encounter the "check_page" that vmscan is
- * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
- */
-#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
-#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
-
-static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
- struct vm_area_struct *vma, struct page *check_page)
-{
- struct mm_struct *mm = vma->vm_mm;
- pmd_t *pmd;
- pte_t *pte;
- pte_t pteval;
- spinlock_t *ptl;
- struct page *page;
- unsigned long address;
- unsigned long mmun_start; /* For mmu_notifiers */
- unsigned long mmun_end; /* For mmu_notifiers */
- unsigned long end;
- int ret = SWAP_AGAIN;
- int locked_vma = 0;
-
- address = (vma->vm_start + cursor) & CLUSTER_MASK;
- end = address + CLUSTER_SIZE;
- if (address < vma->vm_start)
- address = vma->vm_start;
- if (end > vma->vm_end)
- end = vma->vm_end;
-
- pmd = mm_find_pmd(mm, address);
- if (!pmd)
- return ret;
-
- mmun_start = address;
- mmun_end = end;
- mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
-
- /*
- * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
- * keep the sem while scanning the cluster for mlocking pages.
- */
- if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
- locked_vma = (vma->vm_flags & VM_LOCKED);
- if (!locked_vma)
- up_read(&vma->vm_mm->mmap_sem); /* don't need it */
- }
-
- pte = pte_offset_map_lock(mm, pmd, address, &ptl);
-
- /* Update high watermark before we lower rss */
- update_hiwater_rss(mm);
-
- for (; address < end; pte++, address += PAGE_SIZE) {
- if (!pte_present(*pte))
- continue;
- page = vm_normal_page(vma, address, *pte);
- BUG_ON(!page || PageAnon(page));
-
- if (locked_vma) {
- if (page == check_page) {
- /* we know we have check_page locked */
- mlock_vma_page(page);
- ret = SWAP_MLOCK;
- } else if (trylock_page(page)) {
- /*
- * If we can lock the page, perform mlock.
- * Otherwise leave the page alone, it will be
- * eventually encountered again later.
- */
- mlock_vma_page(page);
- unlock_page(page);
- }
- continue; /* don't unmap */
- }
-
- if (ptep_clear_flush_young_notify(vma, address, pte))
- continue;
-
- /* Nuke the page table entry. */
- flush_cache_page(vma, address, pte_pfn(*pte));
- pteval = ptep_clear_flush(vma, address, pte);
-
- /* If nonlinear, store the file page offset in the pte. */
- if (page->index != linear_page_index(vma, address)) {
- pte_t ptfile = pgoff_to_pte(page->index);
- if (pte_soft_dirty(pteval))
- pte_file_mksoft_dirty(ptfile);
- set_pte_at(mm, address, pte, ptfile);
- }
-
- /* Move the dirty bit to the physical page now the pte is gone. */
- if (pte_dirty(pteval))
- set_page_dirty(page);
-
- page_remove_rmap(page);
- page_cache_release(page);
- dec_mm_counter(mm, MM_FILEPAGES);
- (*mapcount)--;
- }
- pte_unmap_unlock(pte - 1, ptl);
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
- if (locked_vma)
- up_read(&vma->vm_mm->mmap_sem);
- return ret;
-}
-
-static int try_to_unmap_nonlinear(struct page *page,
- struct address_space *mapping, void *arg)
-{
- struct vm_area_struct *vma;
- int ret = SWAP_AGAIN;
- unsigned long cursor;
- unsigned long max_nl_cursor = 0;
- unsigned long max_nl_size = 0;
- unsigned int mapcount;
-
- list_for_each_entry(vma,
- &mapping->i_mmap_nonlinear, shared.nonlinear) {
-
- cursor = (unsigned long) vma->vm_private_data;
- if (cursor > max_nl_cursor)
- max_nl_cursor = cursor;
- cursor = vma->vm_end - vma->vm_start;
- if (cursor > max_nl_size)
- max_nl_size = cursor;
- }
-
- if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */
- return SWAP_FAIL;
- }
-
- /*
- * We don't try to search for this page in the nonlinear vmas,
- * and page_referenced wouldn't have found it anyway. Instead
- * just walk the nonlinear vmas trying to age and unmap some.
- * The mapcount of the page we came in with is irrelevant,
- * but even so use it as a guide to how hard we should try?
- */
- mapcount = page_mapcount(page);
- if (!mapcount)
- return ret;
-
- cond_resched();
-
- max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
- if (max_nl_cursor == 0)
- max_nl_cursor = CLUSTER_SIZE;
-
- do {
- list_for_each_entry(vma,
- &mapping->i_mmap_nonlinear, shared.nonlinear) {
-
- cursor = (unsigned long) vma->vm_private_data;
- while (cursor < max_nl_cursor &&
- cursor < vma->vm_end - vma->vm_start) {
- if (try_to_unmap_cluster(cursor, &mapcount,
- vma, page) == SWAP_MLOCK)
- ret = SWAP_MLOCK;
- cursor += CLUSTER_SIZE;
- vma->vm_private_data = (void *) cursor;
- if ((int)mapcount <= 0)
- return ret;
- }
- vma->vm_private_data = (void *) max_nl_cursor;
- }
- cond_resched();
- max_nl_cursor += CLUSTER_SIZE;
- } while (max_nl_cursor <= max_nl_size);
-
- /*
- * Don't loop forever (perhaps all the remaining pages are
- * in locked vmas). Reset cursor on all unreserved nonlinear
- * vmas, now forgetting on which ones it had fallen behind.
- */
- list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear)
- vma->vm_private_data = NULL;
-
- return ret;
-}
-
bool is_vma_temporary_stack(struct vm_area_struct *vma)
{
int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
@@ -1498,7 +1297,6 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
.rmap_one = try_to_unmap_one,
.arg = (void *)flags,
.done = page_not_mapped,
- .file_nonlinear = try_to_unmap_nonlinear,
.anon_lock = page_lock_anon_vma_read,
};
@@ -1544,12 +1342,6 @@ int try_to_munlock(struct page *page)
.rmap_one = try_to_unmap_one,
.arg = (void *)TTU_MUNLOCK,
.done = page_not_mapped,
- /*
- * We don't bother to try to find the munlocked page in
- * nonlinears. It's costly. Instead, later, page reclaim logic
- * may call try_to_unmap() and recover PG_mlocked lazily.
- */
- .file_nonlinear = NULL,
.anon_lock = page_lock_anon_vma_read,
};
@@ -1678,14 +1470,6 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
goto done;
}
- if (!rwc->file_nonlinear)
- goto done;
-
- if (list_empty(&mapping->i_mmap_nonlinear))
- goto done;
-
- ret = rwc->file_nonlinear(page, mapping, rwc->arg);
-
done:
mutex_unlock(&mapping->i_mmap_mutex);
return ret;
--
2.0.0.rc0
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