Messages in this thread Patch in this message |  | | | From | Minchan Kim <> | | Subject | [PATCH] memcg: clean up migration | | Date | Mon, 28 Feb 2011 00:49:25 +0900 |
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This patch cleans up unncessary BUG_ON check and confusing charge variable.
That's because memcg charge/uncharge could be handled by mem_cgroup_[prepare/end] migration itself so charge local variable in unmap_and_move lost the role since we introduced 01b1ae63c2.
And mem_cgroup_prepare_migratio return 0 if only it is successful. Otherwise, it jumps to unlock label to clean up so BUG_ON(charge) isn;t meaningless.
Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> --- mm/memcontrol.c | 1 + mm/migrate.c | 14 ++++---------- 2 files changed, 5 insertions(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2fc97fc..6832926 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2872,6 +2872,7 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry, /* * Before starting migration, account PAGE_SIZE to mem_cgroup that the old * page belongs to. + * Return 0 if charge is successful. Otherwise return -errno. */ int mem_cgroup_prepare_migration(struct page *page, struct page *newpage, struct mem_cgroup **ptr, gfp_t gfp_mask) diff --git a/mm/migrate.c b/mm/migrate.c index eb083a6..737c2e5 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -622,7 +622,6 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, int *result = NULL; struct page *newpage = get_new_page(page, private, &result); int remap_swapcache = 1; - int charge = 0; struct mem_cgroup *mem; struct anon_vma *anon_vma = NULL; @@ -637,9 +636,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, if (unlikely(split_huge_page(page))) goto move_newpage; - /* prepare cgroup just returns 0 or -ENOMEM */ rc = -EAGAIN; - if (!trylock_page(page)) { if (!force) goto move_newpage; @@ -678,13 +675,11 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, } /* charge against new page */ - charge = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL); - if (charge == -ENOMEM) { - rc = -ENOMEM; + rc = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL); + if (rc) goto unlock; - } - BUG_ON(charge); + rc = -EAGAIN; if (PageWriteback(page)) { if (!force || !sync) goto uncharge; @@ -767,8 +762,7 @@ skip_unmap: drop_anon_vma(anon_vma); uncharge: - if (!charge) - mem_cgroup_end_migration(mem, page, newpage, rc == 0); + mem_cgroup_end_migration(mem, page, newpage, rc == 0); unlock: unlock_page(page); -- 1.7.1
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