Messages in this thread Patch in this message | | | Date | Wed, 17 Sep 2008 16:55:44 +0900 | From | Daisuke Nishimura <> | Subject | [PATCH -mm] memcg: fix handling of shmem migration(v2) |
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Before this patch, if migrating shmem/tmpfs pages, newpage would be charged with PAGE_CGROUP_FLAG_FILE set, while oldpage has been charged without the flag.
The problem here is mem_cgroup_move_lists doesn't clear(or set) the PAGE_CGROUP_FLAG_FILE flag, so pc->flags of the newpage remains PAGE_CGROUP_FLAG_FILE set even when the pc is moved to another lru(anon) by mem_cgroup_move_lists. And this leads to incorrect MEM_CGROUP_ZSTAT. (In my test, I see an underflow of MEM_CGROUP_ZSTAT(active_file). As a result, mem_cgroup_calc_reclaim returns very huge number and causes soft lockup on page reclaim.)
I'm not sure if mem_cgroup_move_lists should handle PAGE_CGROUP_FLAG_FILE or not(I suppose it should be used to move between active <-> inactive, not anon <-> file), I added MEM_CGROUP_CHARGE_TYPE_SHMEM for precharge at shmem's page migration.
ChangeLog: v1->v2 - instead of modifying migrate.c, modify memcontrol.c only. - add MEM_CGROUP_CHARGE_TYPE_SHMEM.
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> --- mm/memcontrol.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2979d22..ef8812d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -179,6 +179,7 @@ enum charge_type { MEM_CGROUP_CHARGE_TYPE_CACHE = 0, MEM_CGROUP_CHARGE_TYPE_MAPPED, MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */ + MEM_CGROUP_CHARGE_TYPE_SHMEM, /* used by page migration of shmem */ }; /* @@ -579,8 +580,10 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm, pc->flags |= PAGE_CGROUP_FLAG_FILE; else pc->flags |= PAGE_CGROUP_FLAG_ACTIVE; - } else + } else if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED) pc->flags = PAGE_CGROUP_FLAG_ACTIVE; + else /* MEM_CGROUP_CHARGE_TYPE_SHMEM */ + pc->flags = PAGE_CGROUP_FLAG_CACHE | PAGE_CGROUP_FLAG_ACTIVE; lock_page_cgroup(page); if (unlikely(page_get_page_cgroup(page))) { @@ -739,8 +742,12 @@ int mem_cgroup_prepare_migration(struct page *page, struct page *newpage) if (pc) { mem = pc->mem_cgroup; css_get(&mem->css); - if (pc->flags & PAGE_CGROUP_FLAG_CACHE) - ctype = MEM_CGROUP_CHARGE_TYPE_CACHE; + if (pc->flags & PAGE_CGROUP_FLAG_CACHE) { + if (page_is_file_cache(page)) + ctype = MEM_CGROUP_CHARGE_TYPE_CACHE; + else + ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM; + } } unlock_page_cgroup(page); if (mem) {
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