From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm: stop accounting shadow entries We no longer need to keep track of how many shadow entries are present in a mapping. This saves a few writes to the inode and memory barriers. Link: https://lkml.kernel.org/r/20201026151849.24232-3-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Tested-by: Vishal Verma <vishal.l.verma@xxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 13 ------------- mm/swap_state.c | 4 ---- mm/truncate.c | 1 - mm/workingset.c | 1 - 4 files changed, 19 deletions(-) --- a/mm/filemap.c~mm-stop-accounting-shadow-entries +++ a/mm/filemap.c @@ -142,17 +142,6 @@ static void page_cache_delete(struct add page->mapping = NULL; /* Leave page->index set: truncation lookup relies upon it */ - - if (shadow) { - mapping->nrexceptional += nr; - /* - * Make sure the nrexceptional update is committed before - * the nrpages update so that final truncate racing - * with reclaim does not see both counters 0 at the - * same time and miss a shadow entry. - */ - smp_wmb(); - } mapping->nrpages -= nr; } @@ -925,8 +914,6 @@ noinline int __add_to_page_cache_locked( if (xas_error(&xas)) goto unlock; - if (old) - mapping->nrexceptional--; mapping->nrpages++; /* hugetlb pages do not participate in page cache accounting */ --- a/mm/swap_state.c~mm-stop-accounting-shadow-entries +++ a/mm/swap_state.c @@ -132,7 +132,6 @@ int add_to_swap_cache(struct page *page, xas_store(&xas, page); xas_next(&xas); } - address_space->nrexceptional -= nr_shadows; address_space->nrpages += nr; __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr); __mod_lruvec_page_state(page, NR_SWAPCACHE, nr); @@ -172,8 +171,6 @@ void __delete_from_swap_cache(struct pag xas_next(&xas); } ClearPageSwapCache(page); - if (shadow) - address_space->nrexceptional += nr; address_space->nrpages -= nr; __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr); __mod_lruvec_page_state(page, NR_SWAPCACHE, -nr); @@ -275,7 +272,6 @@ void clear_shadow_from_swap_cache(int ty xas_store(&xas, NULL); nr_shadows++; } - address_space->nrexceptional -= nr_shadows; xa_unlock_irq(&address_space->i_pages); /* search the next swapcache until we meet end */ --- a/mm/truncate.c~mm-stop-accounting-shadow-entries +++ a/mm/truncate.c @@ -40,7 +40,6 @@ static inline void __clear_shadow_entry( if (xas_load(&xas) != entry) return; xas_store(&xas, NULL); - mapping->nrexceptional--; } static void clear_shadow_entry(struct address_space *mapping, pgoff_t index, --- a/mm/workingset.c~mm-stop-accounting-shadow-entries +++ a/mm/workingset.c @@ -554,7 +554,6 @@ static enum lru_status shadow_lru_isolat goto out_invalid; if (WARN_ON_ONCE(node->count != node->nr_values)) goto out_invalid; - mapping->nrexceptional -= node->nr_values; xa_delete_node(node, workingset_update_node); __inc_lruvec_kmem_state(node, WORKINGSET_NODERECLAIM); _
