get_swap_page() is always followed by mem_cgroup_try_charge_swap(). This patch moves mem_cgroup_try_charge_swap() into get_swap_page() and makes get_swap_page() call the function even after swap allocation failure.
This simplifies the callers and consolidates memcg related logic and will ease adding swap related memcg events. Signed-off-by: Tejun Heo <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Vladimir Davydov <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Andrew Morton <[email protected]> --- mm/memcontrol.c | 3 +++ mm/shmem.c | 4 ---- mm/swap_slots.c | 10 +++++++--- mm/swap_state.c | 3 --- 4 files changed, 10 insertions(+), 10 deletions(-) --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6012,6 +6012,9 @@ int mem_cgroup_try_charge_swap(struct pa if (!memcg) return 0; + if (!entry.val) + return 0; + memcg = mem_cgroup_id_get_online(memcg); if (!mem_cgroup_is_root(memcg) && --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1322,9 +1322,6 @@ static int shmem_writepage(struct page * if (!swap.val) goto redirty; - if (mem_cgroup_try_charge_swap(page, swap)) - goto free_swap; - /* * Add inode to shmem_unuse()'s list of swapped-out inodes, * if it's not already there. Do it now before the page is @@ -1353,7 +1350,6 @@ static int shmem_writepage(struct page * } mutex_unlock(&shmem_swaplist_mutex); -free_swap: put_swap_page(page, swap); redirty: set_page_dirty(page); --- a/mm/swap_slots.c +++ b/mm/swap_slots.c @@ -317,7 +317,7 @@ swp_entry_t get_swap_page(struct page *p if (PageTransHuge(page)) { if (IS_ENABLED(CONFIG_THP_SWAP)) get_swap_pages(1, true, &entry); - return entry; + goto out; } /* @@ -347,10 +347,14 @@ repeat: } mutex_unlock(&cache->alloc_lock); if (entry.val) - return entry; + goto out; } get_swap_pages(1, false, &entry); - +out: + if (mem_cgroup_try_charge_swap(page, entry)) { + put_swap_page(page, entry); + entry.val = 0; + } return entry; } --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -216,9 +216,6 @@ int add_to_swap(struct page *page) if (!entry.val) return 0; - if (mem_cgroup_try_charge_swap(page, entry)) - goto fail; - /* * Radix-tree node allocations from PF_MEMALLOC contexts could * completely exhaust the page allocator. __GFP_NOMEMALLOC
