Now, we have an infrastructure in rmap_walk() to handle difference
from variants of rmap traversing functions.
So, just use it in try_to_munlock().
In this patch, I change following things.
1. remove some variants of rmap traversing functions.
cf> try_to_unmap_ksm, try_to_unmap_anon, try_to_unmap_file
2. mechanical change to use rmap_walk() in try_to_munlock().
3. copy and paste comments.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 0eef8cb..91b9719 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -75,7 +75,6 @@ struct page *ksm_might_need_to_copy(struct page *page,
int page_referenced_ksm(struct page *page,
struct mem_cgroup *memcg, unsigned long *vm_flags);
-int try_to_unmap_ksm(struct page *page, enum ttu_flags flags);
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
void ksm_migrate_page(struct page *newpage, struct page *oldpage);
@@ -114,11 +113,6 @@ static inline int page_referenced_ksm(struct page *page,
return 0;
}
-static inline int try_to_unmap_ksm(struct page *page, enum ttu_flags flags)
-{
- return 0;
-}
-
static inline int rmap_walk_ksm(struct page *page,
struct rmap_walk_control *rwc)
{
diff --git a/mm/ksm.c b/mm/ksm.c
index e1b0198..4f25cf7 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1946,56 +1946,6 @@ out:
return referenced;
}
-int try_to_unmap_ksm(struct page *page, enum ttu_flags flags)
-{
- struct stable_node *stable_node;
- struct rmap_item *rmap_item;
- int ret = SWAP_AGAIN;
- int search_new_forks = 0;
-
- VM_BUG_ON(!PageKsm(page));
- VM_BUG_ON(!PageLocked(page));
-
- stable_node = page_stable_node(page);
- if (!stable_node)
- return SWAP_FAIL;
-again:
- hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
- struct anon_vma *anon_vma = rmap_item->anon_vma;
- struct anon_vma_chain *vmac;
- struct vm_area_struct *vma;
-
- anon_vma_lock_read(anon_vma);
- anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
- 0, ULONG_MAX) {
- vma = vmac->vma;
- if (rmap_item->address < vma->vm_start ||
- rmap_item->address >= vma->vm_end)
- continue;
- /*
- * Initially we examine only the vma which covers this
- * rmap_item; but later, if there is still work to do,
- * we examine covering vmas in other mms: in case they
- * were forked from the original since ksmd passed.
- */
- if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
- continue;
-
- ret = try_to_unmap_one(page, vma,
- rmap_item->address, (void *)flags);
- if (ret != SWAP_AGAIN || !page_mapped(page)) {
- anon_vma_unlock_read(anon_vma);
- goto out;
- }
- }
- anon_vma_unlock_read(anon_vma);
- }
- if (!search_new_forks++)
- goto again;
-out:
- return ret;
-}
-
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
{
struct stable_node *stable_node;
diff --git a/mm/rmap.c b/mm/rmap.c
index 7407710..860a393 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1515,110 +1515,6 @@ static int skip_vma_temporary_stack(struct vm_area_struct *vma, void *arg)
return (int)is_vma_temporary_stack(vma);
}
-/**
- * try_to_unmap_anon - unmap or unlock anonymous page using the object-based
- * rmap method
- * @page: the page to unmap/unlock
- * @flags: action and flags
- *
- * Find all the mappings of a page using the mapping pointer and the vma chains
- * contained in the anon_vma struct it points to.
- *
- * This function is only called from try_to_unmap/try_to_munlock for
- * anonymous pages.
- * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
- * where the page was found will be held for write. So, we won't recheck
- * vm_flags for that VMA. That should be OK, because that vma shouldn't be
- * 'LOCKED.
- */
-static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
-{
- struct anon_vma *anon_vma;
- pgoff_t pgoff;
- struct anon_vma_chain *avc;
- int ret = SWAP_AGAIN;
-
- anon_vma = page_lock_anon_vma_read(page);
- if (!anon_vma)
- return ret;
-
- pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
- struct vm_area_struct *vma = avc->vma;
- unsigned long address;
-
- /*
- * During exec, a temporary VMA is setup and later moved.
- * The VMA is moved under the anon_vma lock but not the
- * page tables leading to a race where migration cannot
- * find the migration ptes. Rather than increasing the
- * locking requirements of exec(), migration skips
- * temporary VMAs until after exec() completes.
- */
- if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) &&
- is_vma_temporary_stack(vma))
- continue;
-
- address = vma_address(page, vma);
- ret = try_to_unmap_one(page, vma, address, (void *)flags);
- if (ret != SWAP_AGAIN || !page_mapped(page))
- break;
- }
-
- page_unlock_anon_vma_read(anon_vma);
- return ret;
-}
-
-/**
- * try_to_unmap_file - unmap/unlock file page using the object-based rmap method
- * @page: the page to unmap/unlock
- * @flags: action and flags
- *
- * Find all the mappings of a page using the mapping pointer and the vma chains
- * contained in the address_space struct it points to.
- *
- * This function is only called from try_to_unmap/try_to_munlock for
- * object-based pages.
- * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
- * where the page was found will be held for write. So, we won't recheck
- * vm_flags for that VMA. That should be OK, because that vma shouldn't be
- * 'LOCKED.
- */
-static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
-{
- struct address_space *mapping = page->mapping;
- pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- struct vm_area_struct *vma;
- int ret = SWAP_AGAIN;
-
- if (PageHuge(page))
- pgoff = page->index << compound_order(page);
-
- mutex_lock(&mapping->i_mmap_mutex);
- vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
- unsigned long address = vma_address(page, vma);
- ret = try_to_unmap_one(page, vma, address, (void *)flags);
- if (ret != SWAP_AGAIN || !page_mapped(page))
- goto out;
- }
-
- if (list_empty(&mapping->i_mmap_nonlinear))
- goto out;
-
- /*
- * 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(TTU_MUNLOCK) and recover PG_mlocked lazily.
- */
- if (TTU_ACTION(flags) == TTU_MUNLOCK)
- goto out;
-
- ret = try_to_unmap_nonlinear(page, mapping, vma);
-out:
- mutex_unlock(&mapping->i_mmap_mutex);
- return ret;
-}
-
static int page_not_mapped(struct page *page)
{
return !page_mapped(page);
@@ -1687,14 +1583,26 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
*/
int try_to_munlock(struct page *page)
{
+ int ret;
+ struct rmap_walk_control rwc;
+
VM_BUG_ON(!PageLocked(page) || PageLRU(page));
- if (unlikely(PageKsm(page)))
- return try_to_unmap_ksm(page, TTU_MUNLOCK);
- else if (PageAnon(page))
- return try_to_unmap_anon(page, TTU_MUNLOCK);
- else
- return try_to_unmap_file(page, TTU_MUNLOCK);
+ memset(&rwc, 0, sizeof(rwc));
+ rwc.main = try_to_unmap_one;
+ rwc.arg = (void *)TTU_MUNLOCK;
+ rwc.main_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(TTU_MUNLOCK) and recover PG_mlocked lazily.
+ */
+ rwc.file_nonlinear = NULL;
+ rwc.anon_lock = page_lock_anon_vma_read;
+
+ ret = rmap_walk(page, &rwc);
+ return ret;
}
void __put_anon_vma(struct anon_vma *anon_vma)
@@ -1730,8 +1638,18 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page,
}
/*
- * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
- * Called by migrate.c to remove migration ptes, but might be used more later.
+ * rmap_walk_anon - do something to anonymous page using the object-based
+ * rmap method
+ * @page: the page to be handled
+ * @rwc: control variable according to each walk type
+ *
+ * Find all the mappings of a page using the mapping pointer and the vma chains
+ * contained in the anon_vma struct it points to.
+ *
+ * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
+ * where the page was found will be held for write. So, we won't recheck
+ * vm_flags for that VMA. That should be OK, because that vma shouldn't be
+ * LOCKED.
*/
static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
{
@@ -1761,6 +1679,19 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
return ret;
}
+/*
+ * rmap_walk_file - do something to file page using the object-based rmap method
+ * @page: the page to be handled
+ * @rwc: control variable according to each walk type
+ *
+ * Find all the mappings of a page using the mapping pointer and the vma chains
+ * contained in the address_space struct it points to.
+ *
+ * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
+ * where the page was found will be held for write. So, we won't recheck
+ * vm_flags for that VMA. That should be OK, because that vma shouldn't be
+ * LOCKED.
+ */
static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
{
struct address_space *mapping = page->mapping;
--
1.7.9.5
--
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