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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-12-14 20:59:16 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 11:53:18 -0500
commit93d17715a5b960d34220f2edba3e6cee9b5b1c58 (patch)
tree9ab08ff4169464bf5b8d86c8082296fd6e3d069b
parent338fde90930eaa02f6f394daa23d35a410af5852 (diff)
ksm: three remove_rmap_item_from_tree cleanups
1. remove_rmap_item_from_tree() is called as a precaution from various places: don't dirty the rmap_item cacheline unnecessarily, just mask the flags out of the address when they have been set. 2. First get_next_rmap_item() removes an unstable rmap_item from its tree, then shortly afterwards cmp_and_merge_page() removes a stable rmap_item from its tree: it's easier just to do both at once (but definitely keep the BUG_ON(age > 1) which guards against a future omission). 3. When cmp_and_merge_page() moves an rmap_item from unstable to stable tree, it does its own rb_erase() and accounting: that's better expressed by remove_rmap_item_from_tree(). Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/ksm.c17
1 files changed, 6 insertions, 11 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index 5575f8628fef..133ea2ca8384 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -453,6 +453,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
453 } 453 }
454 454
455 rmap_item->next = NULL; 455 rmap_item->next = NULL;
456 rmap_item->address &= PAGE_MASK;
456 457
457 } else if (rmap_item->address & NODE_FLAG) { 458 } else if (rmap_item->address & NODE_FLAG) {
458 unsigned char age; 459 unsigned char age;
@@ -467,11 +468,11 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
467 BUG_ON(age > 1); 468 BUG_ON(age > 1);
468 if (!age) 469 if (!age)
469 rb_erase(&rmap_item->node, &root_unstable_tree); 470 rb_erase(&rmap_item->node, &root_unstable_tree);
471
470 ksm_pages_unshared--; 472 ksm_pages_unshared--;
473 rmap_item->address &= PAGE_MASK;
471 } 474 }
472 475
473 rmap_item->address &= PAGE_MASK;
474
475 cond_resched(); /* we're called from many long loops */ 476 cond_resched(); /* we're called from many long loops */
476} 477}
477 478
@@ -1086,8 +1087,7 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
1086 unsigned int checksum; 1087 unsigned int checksum;
1087 int err; 1088 int err;
1088 1089
1089 if (in_stable_tree(rmap_item)) 1090 remove_rmap_item_from_tree(rmap_item);
1090 remove_rmap_item_from_tree(rmap_item);
1091 1091
1092 /* We first start with searching the page inside the stable tree */ 1092 /* We first start with searching the page inside the stable tree */
1093 tree_rmap_item = stable_tree_search(page, page2, rmap_item); 1093 tree_rmap_item = stable_tree_search(page, page2, rmap_item);
@@ -1143,9 +1143,7 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
1143 * tree, and insert it instead as new node in the stable tree. 1143 * tree, and insert it instead as new node in the stable tree.
1144 */ 1144 */
1145 if (!err) { 1145 if (!err) {
1146 rb_erase(&tree_rmap_item->node, &root_unstable_tree); 1146 remove_rmap_item_from_tree(tree_rmap_item);
1147 tree_rmap_item->address &= ~NODE_FLAG;
1148 ksm_pages_unshared--;
1149 1147
1150 /* 1148 /*
1151 * If we fail to insert the page into the stable tree, 1149 * If we fail to insert the page into the stable tree,
@@ -1174,11 +1172,8 @@ static struct rmap_item *get_next_rmap_item(struct mm_slot *mm_slot,
1174 1172
1175 while (cur != &mm_slot->rmap_list) { 1173 while (cur != &mm_slot->rmap_list) {
1176 rmap_item = list_entry(cur, struct rmap_item, link); 1174 rmap_item = list_entry(cur, struct rmap_item, link);
1177 if ((rmap_item->address & PAGE_MASK) == addr) { 1175 if ((rmap_item->address & PAGE_MASK) == addr)
1178 if (!in_stable_tree(rmap_item))
1179 remove_rmap_item_from_tree(rmap_item);
1180 return rmap_item; 1176 return rmap_item;
1181 }
1182 if (rmap_item->address > addr) 1177 if (rmap_item->address > addr)
1183 break; 1178 break;
1184 cur = cur->next; 1179 cur = cur->next;