diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 86 |
1 files changed, 63 insertions, 23 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index e1a95dbcd5f8..763d2fd3cadd 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -154,11 +154,42 @@ static bool global_reclaim(struct scan_control *sc) { return !sc->target_mem_cgroup; } + +/** + * sane_reclaim - is the usual dirty throttling mechanism operational? + * @sc: scan_control in question + * + * The normal page dirty throttling mechanism in balance_dirty_pages() is + * completely broken with the legacy memcg and direct stalling in + * shrink_page_list() is used for throttling instead, which lacks all the + * niceties such as fairness, adaptive pausing, bandwidth proportional + * allocation and configurability. + * + * This function tests whether the vmscan currently in progress can assume + * that the normal dirty throttling mechanism is operational. + */ +static bool sane_reclaim(struct scan_control *sc) +{ + struct mem_cgroup *memcg = sc->target_mem_cgroup; + + if (!memcg) + return true; +#ifdef CONFIG_CGROUP_WRITEBACK + if (memcg->css.cgroup) + return true; +#endif + return false; +} #else static bool global_reclaim(struct scan_control *sc) { return true; } + +static bool sane_reclaim(struct scan_control *sc) +{ + return true; +} #endif static unsigned long zone_reclaimable_pages(struct zone *zone) @@ -452,14 +483,13 @@ static inline int is_page_cache_freeable(struct page *page) return page_count(page) - page_has_private(page) == 2; } -static int may_write_to_queue(struct backing_dev_info *bdi, - struct scan_control *sc) +static int may_write_to_inode(struct inode *inode, struct scan_control *sc) { if (current->flags & PF_SWAPWRITE) return 1; - if (!bdi_write_congested(bdi)) + if (!inode_write_congested(inode)) return 1; - if (bdi == current->backing_dev_info) + if (inode_to_bdi(inode) == current->backing_dev_info) return 1; return 0; } @@ -538,7 +568,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, } if (mapping->a_ops->writepage == NULL) return PAGE_ACTIVATE; - if (!may_write_to_queue(inode_to_bdi(mapping->host), sc)) + if (!may_write_to_inode(mapping->host, sc)) return PAGE_KEEP; if (clear_page_dirty_for_io(page)) { @@ -579,10 +609,14 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, static int __remove_mapping(struct address_space *mapping, struct page *page, bool reclaimed) { + unsigned long flags; + struct mem_cgroup *memcg; + BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); - spin_lock_irq(&mapping->tree_lock); + memcg = mem_cgroup_begin_page_stat(page); + spin_lock_irqsave(&mapping->tree_lock, flags); /* * The non racy check for a busy page. * @@ -620,7 +654,8 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, swp_entry_t swap = { .val = page_private(page) }; mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page); - spin_unlock_irq(&mapping->tree_lock); + spin_unlock_irqrestore(&mapping->tree_lock, flags); + mem_cgroup_end_page_stat(memcg); swapcache_free(swap); } else { void (*freepage)(struct page *); @@ -640,8 +675,9 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, if (reclaimed && page_is_file_cache(page) && !mapping_exiting(mapping)) shadow = workingset_eviction(mapping, page); - __delete_from_page_cache(page, shadow); - spin_unlock_irq(&mapping->tree_lock); + __delete_from_page_cache(page, shadow, memcg); + spin_unlock_irqrestore(&mapping->tree_lock, flags); + mem_cgroup_end_page_stat(memcg); if (freepage != NULL) freepage(page); @@ -650,7 +686,8 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, return 1; cannot_free: - spin_unlock_irq(&mapping->tree_lock); + spin_unlock_irqrestore(&mapping->tree_lock, flags); + mem_cgroup_end_page_stat(memcg); return 0; } @@ -917,7 +954,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, */ mapping = page_mapping(page); if (((dirty || writeback) && mapping && - bdi_write_congested(inode_to_bdi(mapping->host))) || + inode_write_congested(mapping->host)) || (writeback && PageReclaim(page))) nr_congested++; @@ -935,11 +972,11 @@ static unsigned long shrink_page_list(struct list_head *page_list, * note that the LRU is being scanned too quickly and the * caller can stall after page list has been processed. * - * 2) Global reclaim encounters a page, memcg encounters a - * page that is not marked for immediate reclaim or - * the caller does not have __GFP_FS (or __GFP_IO if it's - * simply going to swap, not to fs). In this case mark - * the page for immediate reclaim and continue scanning. + * 2) Global or new memcg reclaim encounters a page that is + * not marked for immediate reclaim, or the caller does not + * have __GFP_FS (or __GFP_IO if it's simply going to swap, + * not to fs). In this case mark the page for immediate + * reclaim and continue scanning. * * Require may_enter_fs because we would wait on fs, which * may not have submitted IO yet. And the loop driver might @@ -948,7 +985,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, * __GFP_IO|__GFP_FS for this reason); but more thought * would probably show more reasons. * - * 3) memcg encounters a page that is not already marked + * 3) Legacy memcg encounters a page that is already marked * PageReclaim. memcg does not have any dirty pages * throttling so we could easily OOM just because too many * pages are in writeback and there is nothing else to @@ -963,7 +1000,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, goto keep_locked; /* Case 2 above */ - } else if (global_reclaim(sc) || + } else if (sane_reclaim(sc) || !PageReclaim(page) || !may_enter_fs) { /* * This is slightly racy - end_page_writeback() @@ -978,12 +1015,15 @@ static unsigned long shrink_page_list(struct list_head *page_list, */ SetPageReclaim(page); nr_writeback++; - goto keep_locked; /* Case 3 above */ } else { + unlock_page(page); wait_on_page_writeback(page); + /* then go back and try same page again */ + list_add_tail(&page->lru, page_list); + continue; } } @@ -1412,7 +1452,7 @@ static int too_many_isolated(struct zone *zone, int file, if (current_is_kswapd()) return 0; - if (!global_reclaim(sc)) + if (!sane_reclaim(sc)) return 0; if (file) { @@ -1604,10 +1644,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, set_bit(ZONE_WRITEBACK, &zone->flags); /* - * memcg will stall in page writeback so only consider forcibly - * stalling for global reclaim + * Legacy memcg will stall in page writeback so avoid forcibly + * stalling here. */ - if (global_reclaim(sc)) { + if (sane_reclaim(sc)) { /* * Tag a zone as congested if all the dirty pages scanned were * backed by a congested BDI and wait_iff_congested will stall. |