The patch titled
Subject: ksm: trivial tidyups
has been added to the -mm tree. Its filename is
ksm-trivial-tidyups.patch
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: ksm: trivial tidyups
Add NUMA() and DO_NUMA() macros to minimize blight of #ifdef CONFIG_NUMAs
(but indeed we don't want to expand struct rmap_item by nid when not
NUMA). Add comment, remove "unsigned" from rmap_item->nid, as "int nid"
elsewhere. Define ksm_merge_across_nodes 1U when #ifndef NUMA to help
optimizing out. Use ?: in get_kpfn_nid(). Adjust a few comments noticed
in ongoing work.
Leave stable_tree_insert()'s rb_linkage until after the node has been set
up, as unstable_tree_search_insert() does: ksm_thread_mutex and page lock
make either way safe, but we're going to copy and I prefer this precedent.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Petr Holasek <pholasek@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Izik Eidus <izik.eidus@xxxxxxxxxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 48 ++++++++++++++++++++++--------------------------
1 file changed, 22 insertions(+), 26 deletions(-)
diff -puN mm/ksm.c~ksm-trivial-tidyups mm/ksm.c
--- a/mm/ksm.c~ksm-trivial-tidyups
+++ a/mm/ksm.c
@@ -41,6 +41,14 @@
#include <asm/tlbflush.h>
#include "internal.h"
+#ifdef CONFIG_NUMA
+#define NUMA(x) (x)
+#define DO_NUMA(x) (x)
+#else
+#define NUMA(x) (0)
+#define DO_NUMA(x) do { } while (0)
+#endif
+
/*
* A few notes about the KSM scanning process,
* to make it easier to understand the data structures below:
@@ -130,6 +138,7 @@ struct stable_node {
* @mm: the memory structure this rmap_item is pointing into
* @address: the virtual address this rmap_item tracks (+ flags in low bits)
* @oldchecksum: previous checksum of the page at that virtual address
+ * @nid: NUMA node id of unstable tree in which linked (may not match page)
* @node: rb node of this rmap_item in the unstable tree
* @head: pointer to stable_node heading this list in the stable tree
* @hlist: link into hlist of rmap_items hanging off that stable_node
@@ -141,7 +150,7 @@ struct rmap_item {
unsigned long address; /* + low bits used for flags below */
unsigned int oldchecksum; /* when unstable */
#ifdef CONFIG_NUMA
- unsigned int nid;
+ int nid;
#endif
union {
struct rb_node node; /* when node of unstable tree */
@@ -192,8 +201,12 @@ static unsigned int ksm_thread_pages_to_
/* Milliseconds ksmd should sleep between batches */
static unsigned int ksm_thread_sleep_millisecs = 20;
+#ifdef CONFIG_NUMA
/* Zeroed when merging across nodes is not allowed */
static unsigned int ksm_merge_across_nodes = 1;
+#else
+#define ksm_merge_across_nodes 1U
+#endif
#define KSM_RUN_STOP 0
#define KSM_RUN_MERGE 1
@@ -456,10 +469,7 @@ out: page = NULL;
*/
static inline int get_kpfn_nid(unsigned long kpfn)
{
- if (ksm_merge_across_nodes)
- return 0;
- else
- return pfn_to_nid(kpfn);
+ return ksm_merge_across_nodes ? 0 : pfn_to_nid(kpfn);
}
static void remove_node_from_stable_tree(struct stable_node *stable_node)
@@ -479,7 +489,6 @@ static void remove_node_from_stable_tree
}
nid = get_kpfn_nid(stable_node->kpfn);
-
rb_erase(&stable_node->node, &root_stable_tree[nid]);
free_stable_node(stable_node);
}
@@ -578,13 +587,8 @@ static void remove_rmap_item_from_tree(s
age = (unsigned char)(ksm_scan.seqnr - rmap_item->address);
BUG_ON(age > 1);
if (!age)
-#ifdef CONFIG_NUMA
rb_erase(&rmap_item->node,
- &root_unstable_tree[rmap_item->nid]);
-#else
- rb_erase(&rmap_item->node, &root_unstable_tree[0]);
-#endif
-
+ &root_unstable_tree[NUMA(rmap_item->nid)]);
ksm_pages_unshared--;
rmap_item->address &= PAGE_MASK;
}
@@ -604,7 +608,7 @@ static void remove_trailing_rmap_items(s
}
/*
- * Though it's very tempting to unmerge in_stable_tree(rmap_item)s rather
+ * Though it's very tempting to unmerge rmap_items from stable tree rather
* than check every pte of a given vma, the locking doesn't quite work for
* that - an rmap_item is assigned to the stable tree after inserting ksm
* page and upping mmap_sem. Nor does it fit with the way we skip dup'ing
@@ -1058,7 +1062,7 @@ static struct page *stable_tree_search(s
}
/*
- * stable_tree_insert - insert rmap_item pointing to new ksm page
+ * stable_tree_insert - insert stable tree node pointing to new ksm page
* into the stable tree.
*
* This function returns the stable tree node just allocated on success,
@@ -1108,13 +1112,11 @@ static struct stable_node *stable_tree_i
if (!stable_node)
return NULL;
- rb_link_node(&stable_node->node, parent, new);
- rb_insert_color(&stable_node->node, &root_stable_tree[nid]);
-
INIT_HLIST_HEAD(&stable_node->hlist);
-
stable_node->kpfn = kpfn;
set_page_stable_node(kpage, stable_node);
+ rb_link_node(&stable_node->node, parent, new);
+ rb_insert_color(&stable_node->node, &root_stable_tree[nid]);
return stable_node;
}
@@ -1170,8 +1172,6 @@ struct rmap_item *unstable_tree_search_i
* If tree_page has been migrated to another NUMA node, it
* will be flushed out and put into the right unstable tree
* next time: only merge with it if merge_across_nodes.
- * Just notice, we don't have similar problem for PageKsm
- * because their migration is disabled now. (62b61f611e)
*/
if (!ksm_merge_across_nodes && page_to_nid(tree_page) != nid) {
put_page(tree_page);
@@ -1195,9 +1195,7 @@ struct rmap_item *unstable_tree_search_i
rmap_item->address |= UNSTABLE_FLAG;
rmap_item->address |= (ksm_scan.seqnr & SEQNR_MASK);
-#ifdef CONFIG_NUMA
- rmap_item->nid = nid;
-#endif
+ DO_NUMA(rmap_item->nid = nid);
rb_link_node(&rmap_item->node, parent, new);
rb_insert_color(&rmap_item->node, root);
@@ -1213,13 +1211,11 @@ struct rmap_item *unstable_tree_search_i
static void stable_tree_append(struct rmap_item *rmap_item,
struct stable_node *stable_node)
{
-#ifdef CONFIG_NUMA
/*
* Usually rmap_item->nid is already set correctly,
* but it may be wrong after switching merge_across_nodes.
*/
- rmap_item->nid = get_kpfn_nid(stable_node->kpfn);
-#endif
+ DO_NUMA(rmap_item->nid = get_kpfn_nid(stable_node->kpfn));
rmap_item->head = stable_node;
rmap_item->address |= STABLE_FLAG;
hlist_add_head(&rmap_item->hlist, &stable_node->hlist);
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
linux-next.patch
revert-x86-mm-make-spurious_fault-check-explicitly-check-the-present-bit.patch
pageattr-prevent-pse-and-gloabl-leftovers-to-confuse-pmd-pte_present-and-pmd_huge.patch
mm-memcg-only-evict-file-pages-when-we-have-plenty.patch
mm-vmscan-save-work-scanning-almost-empty-lru-lists.patch
mm-vmscan-clarify-how-swappiness-highest-priority-memcg-interact.patch
mm-vmscan-improve-comment-on-low-page-cache-handling.patch
mm-vmscan-clean-up-get_scan_count.patch
mm-vmscan-clean-up-get_scan_count-fix.patch
mm-vmscan-compaction-works-against-zones-not-lruvecs.patch
mm-vmscan-compaction-works-against-zones-not-lruvecs-fix.patch
mm-reduce-rmap-overhead-for-ex-ksm-page-copies-created-on-swap-faults.patch
mm-page_allocc-__setup_per_zone_wmarks-make-min_pages-unsigned-long.patch
mm-vmscanc-__zone_reclaim-replace-max_t-with-max.patch
mmksm-use-new-hashtable-implementation.patch
mm-make-madvisemadv_willneed-support-swap-file-prefetch.patch
mm-make-madvisemadv_willneed-support-swap-file-prefetch-fix.patch
mm-make-madvisemadv_willneed-support-swap-file-prefetch-fix-fix.patch
mm-avoid-calling-pgdat_balanced-needlessly.patch
mm-numa-fix-minor-typo-in-numa_next_scan.patch
mm-numa-take-thp-into-account-when-migrating-pages-for-numa-balancing.patch
mm-numa-handle-side-effects-in-count_vm_numa_events-for-config_numa_balancing.patch
mm-move-page-flags-layout-to-separate-header.patch
mm-fold-page-_last_nid-into-page-flags-where-possible.patch
mm-numa-cleanup-flow-of-transhuge-page-migration.patch
mm-dont-inline-page_mapping.patch
swap-make-each-swap-partition-have-one-address_space.patch
swap-make-each-swap-partition-have-one-address_space-fix.patch
swap-add-per-partition-lock-for-swapfile.patch
memcg-reduce-the-size-of-struct-memcg-244-fold.patch
memcg-reduce-the-size-of-struct-memcg-244-fold-fix.patch
ksm-allow-trees-per-numa-node.patch
ksm-add-sysfs-abi-documentation.patch
ksm-trivial-tidyups.patch
ksm-reorganize-ksm_check_stable_tree.patch
ksm-get_ksm_page-locked.patch
ksm-remove-old-stable-nodes-more-thoroughly.patch
ksm-make-ksm-page-migration-possible.patch
ksm-make-merge_across_nodes-migration-safe.patch
ksm-enable-ksm-page-migration.patch
mm-remove-offlining-arg-to-migrate_pages.patch
ksm-stop-hotremove-lockdep-warning.patch
mm-prevent-addition-of-pages-to-swap-if-may_writepage-is-unset.patch
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