From af936a1606246a10c145feac3770f6287f483f02 Mon Sep 17 00:00:00 2001 From: Lee Schermerhorn Date: Sat, 18 Oct 2008 20:26:53 -0700 Subject: [PATCH] vmscan: unevictable LRU scan sysctl This patch adds a function to scan individual or all zones' unevictable lists and move any pages that have become evictable onto the respective zone's inactive list, where shrink_inactive_list() will deal with them. Adds sysctl to scan all nodes, and per node attributes to individual nodes' zones. Kosaki: If evictable page found in unevictable lru when write /proc/sys/vm/scan_unevictable_pages, print filename and file offset of these pages. [akpm@linux-foundation.org: fix one CONFIG_MMU=n build error] [kosaki.motohiro@jp.fujitsu.com: adapt vmscan-unevictable-lru-scan-sysctl.patch to new sysfs API] Signed-off-by: Lee Schermerhorn Signed-off-by: Rik van Riel Signed-off-by: KOSAKI Motohiro Signed-off-by: KOSAKI Motohiro Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/base/node.c | 5 ++ include/linux/rmap.h | 3 + include/linux/swap.h | 15 ++++ kernel/sysctl.c | 10 +++ mm/rmap.c | 4 +- mm/vmscan.c | 166 +++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 201 insertions(+), 2 deletions(-) diff --git a/drivers/base/node.c b/drivers/base/node.c index fb45d88a2446..f5207090885a 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -13,6 +13,7 @@ #include #include #include +#include static struct sysdev_class node_class = { .name = "node", @@ -191,6 +192,8 @@ int register_node(struct node *node, int num, struct node *parent) sysdev_create_file(&node->sysdev, &attr_meminfo); sysdev_create_file(&node->sysdev, &attr_numastat); sysdev_create_file(&node->sysdev, &attr_distance); + + scan_unevictable_register_node(node); } return error; } @@ -210,6 +213,8 @@ void unregister_node(struct node *node) sysdev_remove_file(&node->sysdev, &attr_numastat); sysdev_remove_file(&node->sysdev, &attr_distance); + scan_unevictable_unregister_node(node); + sysdev_unregister(&node->sysdev); } diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 955667e6a52d..1da48db8db09 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -75,6 +75,9 @@ void anon_vma_unlink(struct vm_area_struct *); void anon_vma_link(struct vm_area_struct *); void __anon_vma_link(struct vm_area_struct *); +extern struct anon_vma *page_lock_anon_vma(struct page *page); +extern void page_unlock_anon_vma(struct anon_vma *anon_vma); + /* * rmap interfaces called when adding or removing pte of page */ diff --git a/include/linux/swap.h b/include/linux/swap.h index 07eda69412fb..a3af95b2cb6d 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -7,6 +7,7 @@ #include #include #include +#include #include #include @@ -235,15 +236,29 @@ static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order) #ifdef CONFIG_UNEVICTABLE_LRU extern int page_evictable(struct page *page, struct vm_area_struct *vma); extern void scan_mapping_unevictable_pages(struct address_space *); + +extern unsigned long scan_unevictable_pages; +extern int scan_unevictable_handler(struct ctl_table *, int, struct file *, + void __user *, size_t *, loff_t *); +extern int scan_unevictable_register_node(struct node *node); +extern void scan_unevictable_unregister_node(struct node *node); #else static inline int page_evictable(struct page *page, struct vm_area_struct *vma) { return 1; } + static inline void scan_mapping_unevictable_pages(struct address_space *mapping) { } + +static inline int scan_unevictable_register_node(struct node *node) +{ + return 0; +} + +static inline void scan_unevictable_unregister_node(struct node *node) { } #endif extern int kswapd_run(int nid); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 617d41e4d6a0..b3cc73931d1f 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -833,6 +833,16 @@ static struct ctl_table kern_table[] = { .proc_handler = &proc_dointvec, }, #endif +#ifdef CONFIG_UNEVICTABLE_LRU + { + .ctl_name = CTL_UNNUMBERED, + .procname = "scan_unevictable_pages", + .data = &scan_unevictable_pages, + .maxlen = sizeof(scan_unevictable_pages), + .mode = 0644, + .proc_handler = &scan_unevictable_handler, + }, +#endif /* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt diff --git a/mm/rmap.c b/mm/rmap.c index 7e60df99018e..7e90bebbeb6c 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -181,7 +181,7 @@ void __init anon_vma_init(void) * Getting a lock on a stable anon_vma from a page off the LRU is * tricky: page_lock_anon_vma rely on RCU to guard against the races. */ -static struct anon_vma *page_lock_anon_vma(struct page *page) +struct anon_vma *page_lock_anon_vma(struct page *page) { struct anon_vma *anon_vma; unsigned long anon_mapping; @@ -201,7 +201,7 @@ out: return NULL; } -static void page_unlock_anon_vma(struct anon_vma *anon_vma) +void page_unlock_anon_vma(struct anon_vma *anon_vma) { spin_unlock(&anon_vma->lock); rcu_read_unlock(); diff --git a/mm/vmscan.c b/mm/vmscan.c index e5aaaad159ef..ca64e3e0c518 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include @@ -2363,6 +2364,39 @@ int page_evictable(struct page *page, struct vm_area_struct *vma) return 1; } +static void show_page_path(struct page *page) +{ + char buf[256]; + if (page_is_file_cache(page)) { + struct address_space *mapping = page->mapping; + struct dentry *dentry; + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); + + spin_lock(&mapping->i_mmap_lock); + dentry = d_find_alias(mapping->host); + printk(KERN_INFO "rescued: %s %lu\n", + dentry_path(dentry, buf, 256), pgoff); + spin_unlock(&mapping->i_mmap_lock); + } else { +#if defined(CONFIG_MM_OWNER) && defined(CONFIG_MMU) + struct anon_vma *anon_vma; + struct vm_area_struct *vma; + + anon_vma = page_lock_anon_vma(page); + if (!anon_vma) + return; + + list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { + printk(KERN_INFO "rescued: anon %s\n", + vma->vm_mm->owner->comm); + break; + } + page_unlock_anon_vma(anon_vma); +#endif + } +} + + /** * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list * @page: page to check evictability and move to appropriate lru list @@ -2382,6 +2416,9 @@ retry: ClearPageUnevictable(page); if (page_evictable(page, NULL)) { enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page); + + show_page_path(page); + __dec_zone_state(zone, NR_UNEVICTABLE); list_move(&page->lru, &zone->lru[l].list); __inc_zone_state(zone, NR_INACTIVE_ANON + l); @@ -2451,4 +2488,133 @@ void scan_mapping_unevictable_pages(struct address_space *mapping) } } + +/** + * scan_zone_unevictable_pages - check unevictable list for evictable pages + * @zone - zone of which to scan the unevictable list + * + * Scan @zone's unevictable LRU lists to check for pages that have become + * evictable. Move those that have to @zone's inactive list where they + * become candidates for reclaim, unless shrink_inactive_zone() decides + * to reactivate them. Pages that are still unevictable are rotated + * back onto @zone's unevictable list. + */ +#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ +void scan_zone_unevictable_pages(struct zone *zone) +{ + struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; + unsigned long scan; + unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); + + while (nr_to_scan > 0) { + unsigned long batch_size = min(nr_to_scan, + SCAN_UNEVICTABLE_BATCH_SIZE); + + spin_lock_irq(&zone->lru_lock); + for (scan = 0; scan < batch_size; scan++) { + struct page *page = lru_to_page(l_unevictable); + + if (!trylock_page(page)) + continue; + + prefetchw_prev_lru_page(page, l_unevictable, flags); + + if (likely(PageLRU(page) && PageUnevictable(page))) + check_move_unevictable_page(page, zone); + + unlock_page(page); + } + spin_unlock_irq(&zone->lru_lock); + + nr_to_scan -= batch_size; + } +} + + +/** + * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages + * + * A really big hammer: scan all zones' unevictable LRU lists to check for + * pages that have become evictable. Move those back to the zones' + * inactive list where they become candidates for reclaim. + * This occurs when, e.g., we have unswappable pages on the unevictable lists, + * and we add swap to the system. As such, it runs in the context of a task + * that has possibly/probably made some previously unevictable pages + * evictable. + */ +void scan_all_zones_unevictable_pages(void) +{ + struct zone *zone; + + for_each_zone(zone) { + scan_zone_unevictable_pages(zone); + } +} + +/* + * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of + * all nodes' unevictable lists for evictable pages + */ +unsigned long scan_unevictable_pages; + +int scan_unevictable_handler(struct ctl_table *table, int write, + struct file *file, void __user *buffer, + size_t *length, loff_t *ppos) +{ + proc_doulongvec_minmax(table, write, file, buffer, length, ppos); + + if (write && *(unsigned long *)table->data) + scan_all_zones_unevictable_pages(); + + scan_unevictable_pages = 0; + return 0; +} + +/* + * per node 'scan_unevictable_pages' attribute. On demand re-scan of + * a specified node's per zone unevictable lists for evictable pages. + */ + +static ssize_t read_scan_unevictable_node(struct sys_device *dev, + struct sysdev_attribute *attr, + char *buf) +{ + return sprintf(buf, "0\n"); /* always zero; should fit... */ +} + +static ssize_t write_scan_unevictable_node(struct sys_device *dev, + struct sysdev_attribute *attr, + const char *buf, size_t count) +{ + struct zone *node_zones = NODE_DATA(dev->id)->node_zones; + struct zone *zone; + unsigned long res; + unsigned long req = strict_strtoul(buf, 10, &res); + + if (!req) + return 1; /* zero is no-op */ + + for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { + if (!populated_zone(zone)) + continue; + scan_zone_unevictable_pages(zone); + } + return 1; +} + + +static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, + read_scan_unevictable_node, + write_scan_unevictable_node); + +int scan_unevictable_register_node(struct node *node) +{ + return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); +} + +void scan_unevictable_unregister_node(struct node *node) +{ + sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); +} + #endif -- 2.20.1