diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 454 |
1 files changed, 265 insertions, 189 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 5ed24b94c5e6..a1893c050795 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -95,8 +95,6 @@ struct scan_control { /* Can pages be swapped as part of reclaim? */ int may_swap; - int swappiness; - int order; /* @@ -173,7 +171,8 @@ static unsigned long zone_nr_lru_pages(struct zone *zone, struct scan_control *sc, enum lru_list lru) { if (!scanning_global_lru(sc)) - return mem_cgroup_zone_nr_lru_pages(sc->mem_cgroup, zone, lru); + return mem_cgroup_zone_nr_lru_pages(sc->mem_cgroup, + zone_to_nid(zone), zone_idx(zone), BIT(lru)); return zone_page_state(zone, NR_LRU_BASE + lru); } @@ -250,49 +249,90 @@ unsigned long shrink_slab(struct shrink_control *shrink, unsigned long long delta; unsigned long total_scan; unsigned long max_pass; + int shrink_ret = 0; + long nr; + long new_nr; + long batch_size = shrinker->batch ? shrinker->batch + : SHRINK_BATCH; + + /* + * copy the current shrinker scan count into a local variable + * and zero it so that other concurrent shrinker invocations + * don't also do this scanning work. + */ + do { + nr = shrinker->nr; + } while (cmpxchg(&shrinker->nr, nr, 0) != nr); + total_scan = nr; max_pass = do_shrinker_shrink(shrinker, shrink, 0); delta = (4 * nr_pages_scanned) / shrinker->seeks; delta *= max_pass; do_div(delta, lru_pages + 1); - shrinker->nr += delta; - if (shrinker->nr < 0) { + total_scan += delta; + if (total_scan < 0) { printk(KERN_ERR "shrink_slab: %pF negative objects to " "delete nr=%ld\n", - shrinker->shrink, shrinker->nr); - shrinker->nr = max_pass; + shrinker->shrink, total_scan); + total_scan = max_pass; } /* + * We need to avoid excessive windup on filesystem shrinkers + * due to large numbers of GFP_NOFS allocations causing the + * shrinkers to return -1 all the time. This results in a large + * nr being built up so when a shrink that can do some work + * comes along it empties the entire cache due to nr >>> + * max_pass. This is bad for sustaining a working set in + * memory. + * + * Hence only allow the shrinker to scan the entire cache when + * a large delta change is calculated directly. + */ + if (delta < max_pass / 4) + total_scan = min(total_scan, max_pass / 2); + + /* * Avoid risking looping forever due to too large nr value: * never try to free more than twice the estimate number of * freeable entries. */ - if (shrinker->nr > max_pass * 2) - shrinker->nr = max_pass * 2; + if (total_scan > max_pass * 2) + total_scan = max_pass * 2; - total_scan = shrinker->nr; - shrinker->nr = 0; + trace_mm_shrink_slab_start(shrinker, shrink, nr, + nr_pages_scanned, lru_pages, + max_pass, delta, total_scan); - while (total_scan >= SHRINK_BATCH) { - long this_scan = SHRINK_BATCH; - int shrink_ret; + while (total_scan >= batch_size) { int nr_before; nr_before = do_shrinker_shrink(shrinker, shrink, 0); shrink_ret = do_shrinker_shrink(shrinker, shrink, - this_scan); + batch_size); if (shrink_ret == -1) break; if (shrink_ret < nr_before) ret += nr_before - shrink_ret; - count_vm_events(SLABS_SCANNED, this_scan); - total_scan -= this_scan; + count_vm_events(SLABS_SCANNED, batch_size); + total_scan -= batch_size; cond_resched(); } - shrinker->nr += total_scan; + /* + * move the unused scan count back into the shrinker in a + * manner that handles concurrent updates. If we exhausted the + * scan, there is no need to do an update. + */ + do { + nr = shrinker->nr; + new_nr = total_scan + nr; + if (total_scan <= 0) + break; + } while (cmpxchg(&shrinker->nr, nr, new_nr) != nr); + + trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr); } up_read(&shrinker_rwsem); out: @@ -455,15 +495,6 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, return PAGE_ACTIVATE; } - /* - * Wait on writeback if requested to. This happens when - * direct reclaiming a large contiguous area and the - * first attempt to free a range of pages fails. - */ - if (PageWriteback(page) && - (sc->reclaim_mode & RECLAIM_MODE_SYNC)) - wait_on_page_writeback(page); - if (!PageWriteback(page)) { /* synchronous write or broken a_ops? */ ClearPageReclaim(page); @@ -602,13 +633,14 @@ redo: lru = LRU_UNEVICTABLE; add_page_to_unevictable_list(page); /* - * When racing with an mlock clearing (page is - * unlocked), make sure that if the other thread does - * not observe our setting of PG_lru and fails - * isolation, we see PG_mlocked cleared below and move + * When racing with an mlock or AS_UNEVICTABLE clearing + * (page is unlocked) make sure that if the other thread + * does not observe our setting of PG_lru and fails + * isolation/check_move_unevictable_page, + * we see PG_mlocked/AS_UNEVICTABLE cleared below and move * the page back to the evictable list. * - * The other side is TestClearPageMlocked(). + * The other side is TestClearPageMlocked() or shmem_lock(). */ smp_mb(); } @@ -719,7 +751,10 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages) */ static unsigned long shrink_page_list(struct list_head *page_list, struct zone *zone, - struct scan_control *sc) + struct scan_control *sc, + int priority, + unsigned long *ret_nr_dirty, + unsigned long *ret_nr_writeback) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); @@ -727,6 +762,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, unsigned long nr_dirty = 0; unsigned long nr_congested = 0; unsigned long nr_reclaimed = 0; + unsigned long nr_writeback = 0; cond_resched(); @@ -763,13 +799,12 @@ static unsigned long shrink_page_list(struct list_head *page_list, (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); if (PageWriteback(page)) { + nr_writeback++; /* - * Synchronous reclaim is performed in two passes, - * first an asynchronous pass over the list to - * start parallel writeback, and a second synchronous - * pass to wait for the IO to complete. Wait here - * for any page for which writeback has already - * started. + * Synchronous reclaim cannot queue pages for + * writeback due to the possibility of stack overflow + * but if it encounters a page under writeback, wait + * for the IO to complete. */ if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) && may_enter_fs) @@ -825,6 +860,25 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (PageDirty(page)) { nr_dirty++; + /* + * Only kswapd can writeback filesystem pages to + * avoid risk of stack overflow but do not writeback + * unless under significant pressure. + */ + if (page_is_file_cache(page) && + (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) { + /* + * Immediately reclaim when written back. + * Similar in principal to deactivate_page() + * except we already have the page isolated + * and know it's dirty + */ + inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE); + SetPageReclaim(page); + + goto keep_locked; + } + if (references == PAGEREF_RECLAIM_CLEAN) goto keep_locked; if (!may_enter_fs) @@ -959,6 +1013,8 @@ keep_lumpy: list_splice(&ret_pages, page_list); count_vm_events(PGACTIVATE, pgactivate); + *ret_nr_dirty += nr_dirty; + *ret_nr_writeback += nr_writeback; return nr_reclaimed; } @@ -972,23 +1028,27 @@ keep_lumpy: * * returns 0 on success, -ve errno on failure. */ -int __isolate_lru_page(struct page *page, int mode, int file) +int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file) { + bool all_lru_mode; int ret = -EINVAL; /* Only take pages on the LRU. */ if (!PageLRU(page)) return ret; + all_lru_mode = (mode & (ISOLATE_ACTIVE|ISOLATE_INACTIVE)) == + (ISOLATE_ACTIVE|ISOLATE_INACTIVE); + /* * When checking the active state, we need to be sure we are * dealing with comparible boolean values. Take the logical not * of each. */ - if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) + if (!all_lru_mode && !PageActive(page) != !(mode & ISOLATE_ACTIVE)) return ret; - if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) + if (!all_lru_mode && !!page_is_file_cache(page) != file) return ret; /* @@ -1001,6 +1061,12 @@ int __isolate_lru_page(struct page *page, int mode, int file) ret = -EBUSY; + if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page))) + return ret; + + if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) + return ret; + if (likely(get_page_unless_zero(page))) { /* * Be careful not to clear PageLRU until after we're @@ -1036,7 +1102,8 @@ int __isolate_lru_page(struct page *page, int mode, int file) */ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct list_head *src, struct list_head *dst, - unsigned long *scanned, int order, int mode, int file) + unsigned long *scanned, int order, isolate_mode_t mode, + int file) { unsigned long nr_taken = 0; unsigned long nr_lumpy_taken = 0; @@ -1161,8 +1228,8 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, static unsigned long isolate_pages_global(unsigned long nr, struct list_head *dst, unsigned long *scanned, int order, - int mode, struct zone *z, - int active, int file) + isolate_mode_t mode, + struct zone *z, int active, int file) { int lru = LRU_BASE; if (active) @@ -1354,7 +1421,7 @@ static noinline_for_stack void update_isolated_counts(struct zone *zone, } /* - * Returns true if the caller should wait to clean dirty/writeback pages. + * Returns true if a direct reclaim should wait on pages under writeback. * * If we are direct reclaiming for contiguous pages and we do not reclaim * everything in the list, try again and wait for writeback IO to complete. @@ -1376,7 +1443,7 @@ static inline bool should_reclaim_stall(unsigned long nr_taken, if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) return false; - /* If we have relaimed everything on the isolated list, no stall */ + /* If we have reclaimed everything on the isolated list, no stall */ if (nr_freed == nr_taken) return false; @@ -1408,6 +1475,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, unsigned long nr_taken; unsigned long nr_anon; unsigned long nr_file; + unsigned long nr_dirty = 0; + unsigned long nr_writeback = 0; + isolate_mode_t reclaim_mode = ISOLATE_INACTIVE; while (unlikely(too_many_isolated(zone, file, sc))) { congestion_wait(BLK_RW_ASYNC, HZ/10); @@ -1418,15 +1488,21 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, } set_reclaim_mode(priority, sc, false); + if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM) + reclaim_mode |= ISOLATE_ACTIVE; + lru_add_drain(); + + if (!sc->may_unmap) + reclaim_mode |= ISOLATE_UNMAPPED; + if (!sc->may_writepage) + reclaim_mode |= ISOLATE_CLEAN; + spin_lock_irq(&zone->lru_lock); if (scanning_global_lru(sc)) { - nr_taken = isolate_pages_global(nr_to_scan, - &page_list, &nr_scanned, sc->order, - sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? - ISOLATE_BOTH : ISOLATE_INACTIVE, - zone, 0, file); + nr_taken = isolate_pages_global(nr_to_scan, &page_list, + &nr_scanned, sc->order, reclaim_mode, zone, 0, file); zone->pages_scanned += nr_scanned; if (current_is_kswapd()) __count_zone_vm_events(PGSCAN_KSWAPD, zone, @@ -1435,12 +1511,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned); } else { - nr_taken = mem_cgroup_isolate_pages(nr_to_scan, - &page_list, &nr_scanned, sc->order, - sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? - ISOLATE_BOTH : ISOLATE_INACTIVE, - zone, sc->mem_cgroup, - 0, file); + nr_taken = mem_cgroup_isolate_pages(nr_to_scan, &page_list, + &nr_scanned, sc->order, reclaim_mode, zone, + sc->mem_cgroup, 0, file); /* * mem_cgroup_isolate_pages() keeps track of * scanned pages on its own. @@ -1456,12 +1529,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, spin_unlock_irq(&zone->lru_lock); - nr_reclaimed = shrink_page_list(&page_list, zone, sc); + nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority, + &nr_dirty, &nr_writeback); /* Check if we should syncronously wait for writeback */ if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { set_reclaim_mode(priority, sc, true); - nr_reclaimed += shrink_page_list(&page_list, zone, sc); + nr_reclaimed += shrink_page_list(&page_list, zone, sc, + priority, &nr_dirty, &nr_writeback); } local_irq_disable(); @@ -1471,6 +1546,32 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); + /* + * If reclaim is isolating dirty pages under writeback, it implies + * that the long-lived page allocation rate is exceeding the page + * laundering rate. Either the global limits are not being effective + * at throttling processes due to the page distribution throughout + * zones or there is heavy usage of a slow backing device. The + * only option is to throttle from reclaim context which is not ideal + * as there is no guarantee the dirtying process is throttled in the + * same way balance_dirty_pages() manages. + * + * This scales the number of dirty pages that must be under writeback + * before throttling depending on priority. It is a simple backoff + * function that has the most effect in the range DEF_PRIORITY to + * DEF_PRIORITY-2 which is the priority reclaim is considered to be + * in trouble and reclaim is considered to be in trouble. + * + * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle + * DEF_PRIORITY-1 50% must be PageWriteback + * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble + * ... + * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any + * isolated page is PageWriteback + */ + if (nr_writeback && nr_writeback >= (nr_taken >> (DEF_PRIORITY-priority))) + wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10); + trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, zone_idx(zone), nr_scanned, nr_reclaimed, @@ -1542,19 +1643,26 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, struct page *page; struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); unsigned long nr_rotated = 0; + isolate_mode_t reclaim_mode = ISOLATE_ACTIVE; lru_add_drain(); + + if (!sc->may_unmap) + reclaim_mode |= ISOLATE_UNMAPPED; + if (!sc->may_writepage) + reclaim_mode |= ISOLATE_CLEAN; + spin_lock_irq(&zone->lru_lock); if (scanning_global_lru(sc)) { nr_taken = isolate_pages_global(nr_pages, &l_hold, &pgscanned, sc->order, - ISOLATE_ACTIVE, zone, + reclaim_mode, zone, 1, file); zone->pages_scanned += pgscanned; } else { nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, - ISOLATE_ACTIVE, zone, + reclaim_mode, zone, sc->mem_cgroup, 1, file); /* * mem_cgroup_isolate_pages() keeps track of @@ -1659,7 +1767,7 @@ static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) if (scanning_global_lru(sc)) low = inactive_anon_is_low_global(zone); else - low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); + low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup, zone); return low; } #else @@ -1702,7 +1810,7 @@ static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) if (scanning_global_lru(sc)) low = inactive_file_is_low_global(zone); else - low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); + low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup, zone); return low; } @@ -1729,6 +1837,13 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); } +static int vmscan_swappiness(struct scan_control *sc) +{ + if (scanning_global_lru(sc)) + return vm_swappiness; + return mem_cgroup_swappiness(sc->mem_cgroup); +} + /* * Determine how aggressively the anon and file LRU lists should be * scanned. The relative value of each set of LRU lists is determined @@ -1747,22 +1862,22 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, u64 fraction[2], denominator; enum lru_list l; int noswap = 0; - int force_scan = 0; - - - anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + - zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); - file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + - zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); + bool force_scan = false; - if (((anon + file) >> priority) < SWAP_CLUSTER_MAX) { - /* kswapd does zone balancing and need to scan this zone */ - if (scanning_global_lru(sc) && current_is_kswapd()) - force_scan = 1; - /* memcg may have small limit and need to avoid priority drop */ - if (!scanning_global_lru(sc)) - force_scan = 1; - } + /* + * If the zone or memcg is small, nr[l] can be 0. This + * results in no scanning on this priority and a potential + * priority drop. Global direct reclaim can go to the next + * zone and tends to have no problems. Global kswapd is for + * zone balancing and it needs to scan a minimum amount. When + * reclaiming for a memcg, a priority drop can cause high + * latencies, so it's better to scan a minimum amount there as + * well. + */ + if (scanning_global_lru(sc) && current_is_kswapd()) + force_scan = true; + if (!scanning_global_lru(sc)) + force_scan = true; /* If we have no swap space, do not bother scanning anon pages. */ if (!sc->may_swap || (nr_swap_pages <= 0)) { @@ -1773,6 +1888,11 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, goto out; } + anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + + zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); + file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + + zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); + if (scanning_global_lru(sc)) { free = zone_page_state(zone, NR_FREE_PAGES); /* If we have very few page cache pages, @@ -1789,8 +1909,8 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, * With swappiness at 100, anonymous and file have the same priority. * This scanning priority is essentially the inverse of IO cost. */ - anon_prio = sc->swappiness; - file_prio = 200 - sc->swappiness; + anon_prio = vmscan_swappiness(sc); + file_prio = 200 - vmscan_swappiness(sc); /* * OK, so we have swap space and a fair amount of page cache @@ -1837,23 +1957,9 @@ out: scan = zone_nr_lru_pages(zone, sc, l); if (priority || noswap) { scan >>= priority; - scan = div64_u64(scan * fraction[file], denominator); - } - - /* - * If zone is small or memcg is small, nr[l] can be 0. - * This results no-scan on this priority and priority drop down. - * For global direct reclaim, it can visit next zone and tend - * not to have problems. For global kswapd, it's for zone - * balancing and it need to scan a small amounts. When using - * memcg, priority drop can cause big latency. So, it's better - * to scan small amount. See may_noscan above. - */ - if (!scan && force_scan) { - if (file) - scan = SWAP_CLUSTER_MAX; - else if (!noswap) + if (!scan && force_scan) scan = SWAP_CLUSTER_MAX; + scan = div64_u64(scan * fraction[file], denominator); } nr[l] = scan; } @@ -1933,12 +2039,14 @@ static void shrink_zone(int priority, struct zone *zone, enum lru_list l; unsigned long nr_reclaimed, nr_scanned; unsigned long nr_to_reclaim = sc->nr_to_reclaim; + struct blk_plug plug; restart: nr_reclaimed = 0; nr_scanned = sc->nr_scanned; get_scan_count(zone, sc, nr, priority); + blk_start_plug(&plug); while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || nr[LRU_INACTIVE_FILE]) { for_each_evictable_lru(l) { @@ -1962,6 +2070,7 @@ restart: if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) break; } + blk_finish_plug(&plug); sc->nr_reclaimed += nr_reclaimed; /* @@ -1994,14 +2103,19 @@ restart: * * If a zone is deemed to be full of pinned pages then just give it a light * scan then give up on it. + * + * This function returns true if a zone is being reclaimed for a costly + * high-order allocation and compaction is either ready to begin or deferred. + * This indicates to the caller that it should retry the allocation or fail. */ -static void shrink_zones(int priority, struct zonelist *zonelist, +static bool shrink_zones(int priority, struct zonelist *zonelist, struct scan_control *sc) { struct zoneref *z; struct zone *zone; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; + bool should_abort_reclaim = false; for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(sc->gfp_mask), sc->nodemask) { @@ -2016,6 +2130,23 @@ static void shrink_zones(int priority, struct zonelist *zonelist, continue; if (zone->all_unreclaimable && priority != DEF_PRIORITY) continue; /* Let kswapd poll it */ + if (COMPACTION_BUILD) { + /* + * If we already have plenty of memory free for + * compaction in this zone, don't free any more. + * Even though compaction is invoked for any + * non-zero order, only frequent costly order + * reclamation is disruptive enough to become a + * noticable problem, like transparent huge page + * allocations. + */ + if (sc->order > PAGE_ALLOC_COSTLY_ORDER && + (compaction_suitable(zone, sc->order) || + compaction_deferred(zone))) { + should_abort_reclaim = true; + continue; + } + } /* * This steals pages from memory cgroups over softlimit * and returns the number of reclaimed pages and @@ -2033,6 +2164,8 @@ static void shrink_zones(int priority, struct zonelist *zonelist, shrink_zone(priority, zone, sc); } + + return should_abort_reclaim; } static bool zone_reclaimable(struct zone *zone) @@ -2097,7 +2230,9 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, sc->nr_scanned = 0; if (!priority) disable_swap_token(sc->mem_cgroup); - shrink_zones(priority, zonelist, sc); + if (shrink_zones(priority, zonelist, sc)) + break; + /* * Don't shrink slabs when reclaiming memory from * over limit cgroups @@ -2131,7 +2266,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, */ writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; if (total_scanned > writeback_threshold) { - wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); + wakeup_flusher_threads(laptop_mode ? 0 : total_scanned, + WB_REASON_TRY_TO_FREE_PAGES); sc->may_writepage = 1; } @@ -2179,7 +2315,6 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, .nr_to_reclaim = SWAP_CLUSTER_MAX, .may_unmap = 1, .may_swap = 1, - .swappiness = vm_swappiness, .order = order, .mem_cgroup = NULL, .nodemask = nodemask, @@ -2203,7 +2338,6 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, gfp_t gfp_mask, bool noswap, - unsigned int swappiness, struct zone *zone, unsigned long *nr_scanned) { @@ -2213,7 +2347,6 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, .may_writepage = !laptop_mode, .may_unmap = 1, .may_swap = !noswap, - .swappiness = swappiness, .order = 0, .mem_cgroup = mem, }; @@ -2242,8 +2375,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, gfp_t gfp_mask, - bool noswap, - unsigned int swappiness) + bool noswap) { struct zonelist *zonelist; unsigned long nr_reclaimed; @@ -2253,7 +2385,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, .may_unmap = 1, .may_swap = !noswap, .nr_to_reclaim = SWAP_CLUSTER_MAX, - .swappiness = swappiness, .order = 0, .mem_cgroup = mem_cont, .nodemask = NULL, /* we don't care the placement */ @@ -2310,7 +2441,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, for (i = 0; i <= classzone_idx; i++) present_pages += pgdat->node_zones[i].present_pages; - return balanced_pages > (present_pages >> 2); + /* A special case here: if zone has no page, we think it's balanced */ + return balanced_pages >= (present_pages >> 2); } /* is kswapd sleeping prematurely? */ @@ -2403,7 +2535,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, * we want to put equal scanning pressure on each zone. */ .nr_to_reclaim = ULONG_MAX, - .swappiness = vm_swappiness, .order = order, .mem_cgroup = NULL, }; @@ -2452,6 +2583,9 @@ loop_again: high_wmark_pages(zone), 0, 0)) { end_zone = i; break; + } else { + /* If balanced, clear the congested flag */ + zone_clear_flag(zone, ZONE_CONGESTED); } } if (i < 0) @@ -2642,6 +2776,8 @@ out: /* If balanced, clear the congested flag */ zone_clear_flag(zone, ZONE_CONGESTED); + if (i <= *classzone_idx) + balanced += zone->present_pages; } } @@ -2715,7 +2851,9 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) static int kswapd(void *p) { unsigned long order, new_order; + unsigned balanced_order; int classzone_idx, new_classzone_idx; + int balanced_classzone_idx; pg_data_t *pgdat = (pg_data_t*)p; struct task_struct *tsk = current; @@ -2746,7 +2884,9 @@ static int kswapd(void *p) set_freezable(); order = new_order = 0; + balanced_order = 0; classzone_idx = new_classzone_idx = pgdat->nr_zones - 1; + balanced_classzone_idx = classzone_idx; for ( ; ; ) { int ret; @@ -2755,7 +2895,8 @@ static int kswapd(void *p) * new request of a similar or harder type will succeed soon * so consider going to sleep on the basis we reclaimed at */ - if (classzone_idx >= new_classzone_idx && order == new_order) { + if (balanced_classzone_idx >= new_classzone_idx && + balanced_order == new_order) { new_order = pgdat->kswapd_max_order; new_classzone_idx = pgdat->classzone_idx; pgdat->kswapd_max_order = 0; @@ -2770,9 +2911,12 @@ static int kswapd(void *p) order = new_order; classzone_idx = new_classzone_idx; } else { - kswapd_try_to_sleep(pgdat, order, classzone_idx); + kswapd_try_to_sleep(pgdat, balanced_order, + balanced_classzone_idx); order = pgdat->kswapd_max_order; classzone_idx = pgdat->classzone_idx; + new_order = order; + new_classzone_idx = classzone_idx; pgdat->kswapd_max_order = 0; pgdat->classzone_idx = pgdat->nr_zones - 1; } @@ -2787,7 +2931,9 @@ static int kswapd(void *p) */ if (!ret) { trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); - order = balance_pgdat(pgdat, order, &classzone_idx); + balanced_classzone_idx = classzone_idx; + balanced_order = balance_pgdat(pgdat, order, + &balanced_classzone_idx); } } return 0; @@ -2873,7 +3019,6 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim) .may_writepage = 1, .nr_to_reclaim = nr_to_reclaim, .hibernation_mode = 1, - .swappiness = vm_swappiness, .order = 0, }; struct shrink_control shrink = { @@ -3060,7 +3205,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) .nr_to_reclaim = max_t(unsigned long, nr_pages, SWAP_CLUSTER_MAX), .gfp_mask = gfp_mask, - .swappiness = vm_swappiness, .order = order, }; struct shrink_control shrink = { @@ -3301,66 +3445,12 @@ 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 */ -static void scan_zone_unevictable_pages(struct zone *zone) +static void warn_scan_unevictable_pages(void) { - 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. - */ -static void scan_all_zones_unevictable_pages(void) -{ - struct zone *zone; - - for_each_zone(zone) { - scan_zone_unevictable_pages(zone); - } + printk_once(KERN_WARNING + "The scan_unevictable_pages sysctl/node-interface has been " + "disabled for lack of a legitimate use case. If you have " + "one, please send an email to linux-mm@kvack.org.\n"); } /* @@ -3373,11 +3463,8 @@ int scan_unevictable_handler(struct ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) { + warn_scan_unevictable_pages(); proc_doulongvec_minmax(table, write, buffer, length, ppos); - - if (write && *(unsigned long *)table->data) - scan_all_zones_unevictable_pages(); - scan_unevictable_pages = 0; return 0; } @@ -3392,6 +3479,7 @@ static ssize_t read_scan_unevictable_node(struct sys_device *dev, struct sysdev_attribute *attr, char *buf) { + warn_scan_unevictable_pages(); return sprintf(buf, "0\n"); /* always zero; should fit... */ } @@ -3399,19 +3487,7 @@ 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); - } + warn_scan_unevictable_pages(); return 1; } |