Messages in this thread Patch in this message | | | From | Alex Shi <> | Subject | [PATCH] mm/memcg: remove useless check on page->mem_cgroup | Date | Fri, 31 Jul 2020 11:34:40 +0800 |
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Since readahead page will be charged on memcg too. We don't need to check this exception now. Rmove them is safe as all user pages are charged before use.
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: cgroups@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 21 ++++----------------- 1 file changed, 4 insertions(+), 17 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e84c2b5596f2..9e44ae22d591 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1322,12 +1322,7 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd } memcg = page->mem_cgroup; - /* - * Swapcache readahead pages are added to the LRU - and - * possibly migrated - before they are charged. - */ - if (!memcg) - memcg = root_mem_cgroup; + VM_BUG_ON_PAGE(!memcg, page); mz = mem_cgroup_page_nodeinfo(memcg, page); lruvec = &mz->lruvec; @@ -6897,10 +6892,8 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) if (newpage->mem_cgroup) return; - /* Swapcache readahead pages can get replaced before being charged */ memcg = oldpage->mem_cgroup; - if (!memcg) - return; + VM_BUG_ON_PAGE(!memcg, oldpage); /* Force-charge the new page. The old one will be freed soon */ nr_pages = thp_nr_pages(newpage); @@ -7094,10 +7087,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) return; memcg = page->mem_cgroup; - - /* Readahead page, never charged */ - if (!memcg) - return; + VM_BUG_ON_PAGE(!memcg, page); /* * In case the memcg owning these pages has been offlined and doesn't @@ -7158,10 +7148,7 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) return 0; memcg = page->mem_cgroup; - - /* Readahead page, never charged */ - if (!memcg) - return 0; + VM_BUG_ON_PAGE(!memcg, page); if (!entry.val) { memcg_memory_event(memcg, MEMCG_SWAP_FAIL); -- 1.8.3.1
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