From: Peter Zijlstra Subject: [PATCH 08/31] mm: emergency pool Patch-mainline: not yet Provide means to reserve a specific amount of pages. The emergency pool is separated from the min watermark because ALLOC_HARDER and ALLOC_HIGH modify the watermark in a relative way and thus do not ensure a strict minimum. Signed-off-by: Peter Zijlstra Signed-off-by: Suresh Jayaraman --- include/linux/mmzone.h | 3 + mm/page_alloc.c | 85 +++++++++++++++++++++++++++++++++++++++++++------ mm/vmstat.c | 6 +-- 3 files changed, 81 insertions(+), 13 deletions(-) --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -282,6 +282,7 @@ struct zone_reclaim_stat { struct zone { /* Fields commonly accessed by the page allocator */ + unsigned long pages_emerg; /* emergency pool */ /* zone watermarks, access with *_wmark_pages(zone) macros */ unsigned long watermark[NR_WMARK]; @@ -776,6 +777,8 @@ int sysctl_min_unmapped_ratio_sysctl_han int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); +int adjust_memalloc_reserve(int pages); + extern int numa_zonelist_order_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); extern char numa_zonelist_order[]; --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -173,6 +173,8 @@ static char * const zone_names[MAX_NR_ZO static DEFINE_SPINLOCK(min_free_lock); int min_free_kbytes = 1024; +static DEFINE_MUTEX(var_free_mutex); +int var_free_kbytes; static unsigned long __meminitdata nr_kernel_pages; static unsigned long __meminitdata nr_all_pages; @@ -1457,7 +1459,7 @@ static bool __zone_watermark_ok(struct z if (alloc_flags & ALLOC_HARDER) min -= min / 4; - if (free_pages <= min + z->lowmem_reserve[classzone_idx]) + if (free_pages <= min+z->lowmem_reserve[classzone_idx]+z->pages_emerg) return false; for (o = 0; o < order; o++) { /* At the next order, this order's pages become unavailable */ @@ -1985,7 +1987,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, u { const gfp_t wait = gfp_mask & __GFP_WAIT; struct page *page = NULL; - int alloc_flags; + int alloc_flags = 0; unsigned long pages_reclaimed = 0; unsigned long did_some_progress; bool sync_migration = false; @@ -2144,8 +2146,9 @@ nopage: printk(KERN_INFO "perfectly reliable and the kernel is designed to handle that.\n"); } printk(KERN_INFO "%s: page allocation failure." - " order:%d, mode:0x%x\n", - current->comm, order, gfp_mask); + " order:%d, mode:0x%x, alloc_flags:0x%x pflags:0x%x\n", + current->comm, order, gfp_mask, alloc_flags, + current->flags); dump_stack(); show_mem(); } @@ -2480,9 +2483,9 @@ void show_free_areas(void) "\n", zone->name, K(zone_page_state(zone, NR_FREE_PAGES)), - K(min_wmark_pages(zone)), - K(low_wmark_pages(zone)), - K(high_wmark_pages(zone)), + K(zone->pages_emerg + min_wmark_pages(zone)), + K(zone->pages_emerg + low_wmark_pages(zone)), + K(zone->pages_emerg + high_wmark_pages(zone)), K(zone_page_state(zone, NR_ACTIVE_ANON)), K(zone_page_state(zone, NR_INACTIVE_ANON)), K(zone_page_state(zone, NR_ACTIVE_FILE)), @@ -4863,7 +4866,7 @@ static void calculate_totalreserve_pages } /* we treat the high watermark as reserved pages. */ - max += high_wmark_pages(zone); + max += high_wmark_pages(zone) + zone->pages_emerg; if (max > zone->present_pages) max = zone->present_pages; @@ -4921,7 +4924,8 @@ static void setup_per_zone_lowmem_reserv */ static void __setup_per_zone_wmarks(void) { - unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); + unsigned pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); + unsigned pages_emerg = var_free_kbytes >> (PAGE_SHIFT - 10); unsigned long lowmem_pages = 0; struct zone *zone; unsigned long flags; @@ -4933,11 +4937,13 @@ static void __setup_per_zone_wmarks(void } for_each_zone(zone) { - u64 tmp; + u64 tmp, tmp_emerg; spin_lock_irqsave(&zone->lock, flags); tmp = (u64)pages_min * zone->present_pages; do_div(tmp, lowmem_pages); + tmp_emerg = (u64)pages_emerg * zone->present_pages; + do_div(tmp_emerg, lowmem_pages); if (is_highmem(zone)) { /* * __GFP_HIGH and PF_MEMALLOC allocations usually don't @@ -4956,12 +4962,14 @@ static void __setup_per_zone_wmarks(void if (min_pages > 128) min_pages = 128; zone->watermark[WMARK_MIN] = min_pages; + zone->pages_emerg = 0; } else { /* * If it's a lowmem zone, reserve a number of pages * proportionate to the zone's size. */ zone->watermark[WMARK_MIN] = tmp; + zone->pages_emerg = tmp_emerg; } zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + (tmp >> 2); @@ -5026,6 +5034,63 @@ void setup_per_zone_wmarks(void) spin_unlock_irqrestore(&min_free_lock, flags); } +static void __adjust_memalloc_reserve(int pages) +{ + var_free_kbytes += pages << (PAGE_SHIFT - 10); + BUG_ON(var_free_kbytes < 0); + setup_per_zone_wmarks(); +} + +static int test_reserve_limits(void) +{ + struct zone *zone; + int node; + + for_each_zone(zone) + wakeup_kswapd(zone, 0); + + for_each_online_node(node) { + struct page *page = alloc_pages_node(node, GFP_KERNEL, 0); + if (!page) + return -ENOMEM; + + __free_page(page); + } + + return 0; +} + +/** + * adjust_memalloc_reserve - adjust the memalloc reserve + * @pages: number of pages to add + * + * It adds a number of pages to the memalloc reserve; if + * the number was positive it kicks reclaim into action to + * satisfy the higher watermarks. + * + * returns -ENOMEM when it failed to satisfy the watermarks. + */ +int adjust_memalloc_reserve(int pages) +{ + int err = 0; + + mutex_lock(&var_free_mutex); + __adjust_memalloc_reserve(pages); + if (pages > 0) { + err = test_reserve_limits(); + if (err) { + __adjust_memalloc_reserve(-pages); + goto unlock; + } + } + printk(KERN_DEBUG "Emergency reserve: %d\n", var_free_kbytes); + +unlock: + mutex_unlock(&var_free_mutex); + return err; +} +EXPORT_SYMBOL_GPL(adjust_memalloc_reserve); + /* * Initialise min_free_kbytes. * --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -957,9 +957,9 @@ static void zoneinfo_show_print(struct s "\n spanned %lu" "\n present %lu", zone_page_state(zone, NR_FREE_PAGES), - min_wmark_pages(zone), - low_wmark_pages(zone), - high_wmark_pages(zone), + zone->pages_emerg + min_wmark_pages(zone), + zone->pages_emerg + min_wmark_pages(zone), + zone->pages_emerg + high_wmark_pages(zone), zone->pages_scanned, zone->spanned_pages, zone->present_pages);