The patch titled
Subject: mm: memcg: remove optimization of keeping the root_mem_cgroup LRU lists empty
has been added to the -mm tree. Its filename is
mm-memcg-remove-optimization-of-keeping-the-root_mem_cgroup-lru-lists-empty.patch
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------------------------------------------------------
From: Johannes Weiner <jweiner@xxxxxxxxxx>
Subject: mm: memcg: remove optimization of keeping the root_mem_cgroup LRU lists empty
root_mem_cgroup, lacking a configurable limit, was never subject to limit
reclaim, so the pages charged to it could be kept off its LRU lists. They
would be found on the global per-zone LRU lists upon physical memory
pressure and it made sense to avoid uselessly linking them to both lists.
The global per-zone LRU lists are about to go away on memcg-enabled
kernels, with all pages being exclusively linked to their respective
per-memcg LRU lists. As a result, pages of the root_mem_cgroup must also
be linked to its LRU lists again. This is purely about the LRU list,
root_mem_cgroup is still not charged.
The overhead is temporary until the double-LRU scheme is going away
completely.
Signed-off-by: Johannes Weiner <jweiner@xxxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)
diff -puN mm/memcontrol.c~mm-memcg-remove-optimization-of-keeping-the-root_mem_cgroup-lru-lists-empty mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcg-remove-optimization-of-keeping-the-root_mem_cgroup-lru-lists-empty
+++ a/mm/memcontrol.c
@@ -965,8 +965,6 @@ void mem_cgroup_del_lru_list(struct page
mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
/* huge page split is done under lru_lock. so, we have no races. */
MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
VM_BUG_ON(list_empty(&pc->lru));
list_del_init(&pc->lru);
}
@@ -991,13 +989,11 @@ void mem_cgroup_rotate_reclaimable_page(
return;
pc = lookup_page_cgroup(page);
- /* unused or root page is not rotated. */
+ /* unused page is not rotated. */
if (!PageCgroupUsed(pc))
return;
/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
smp_rmb();
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
list_move_tail(&pc->lru, &mz->lists[lru]);
}
@@ -1011,13 +1007,11 @@ void mem_cgroup_rotate_lru_list(struct p
return;
pc = lookup_page_cgroup(page);
- /* unused or root page is not rotated. */
+ /* unused page is not rotated. */
if (!PageCgroupUsed(pc))
return;
/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
smp_rmb();
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
list_move(&pc->lru, &mz->lists[lru]);
}
@@ -1049,8 +1043,6 @@ void mem_cgroup_add_lru_list(struct page
/* huge page split is done under lru_lock. so, we have no races. */
MEM_CGROUP_ZSTAT(mz, lru) += 1 << compound_order(page);
SetPageCgroupAcctLRU(pc);
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
list_add(&pc->lru, &mz->lists[lru]);
}
_
Subject: Subject: mm: memcg: remove optimization of keeping the root_mem_cgroup LRU lists empty
Patches currently in -mm which might be from jweiner@xxxxxxxxxx are
mm-add-extra-free-kbytes-tunable.patch
mm-memcg-consolidate-hierarchy-iteration-primitives.patch
mm-vmscan-distinguish-global-reclaim-from-global-lru-scanning.patch
mm-vmscan-distinguish-between-memcg-triggering-reclaim-and-memcg-being-scanned.patch
mm-memcg-per-priority-per-zone-hierarchy-scan-generations.patch
mm-move-memcg-hierarchy-reclaim-to-generic-reclaim-code.patch
mm-memcg-remove-optimization-of-keeping-the-root_mem_cgroup-lru-lists-empty.patch
mm-vmscan-convert-global-reclaim-to-per-memcg-lru-lists.patch
mm-collect-lru-list-heads-into-struct-lruvec.patch
mm-make-per-memcg-lru-lists-exclusive.patch
mm-memcg-remove-unused-node-section-info-from-pc-flags.patch
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