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 --- include/linux/mmzone.h | 3 + mm/page_alloc.c | 82 +++++++++++++++++++++++++++++++++++++++++++------ mm/vmstat.c | 6 +-- 3 files changed, 78 insertions(+), 13 deletions(-) Index: linux-2.6/include/linux/mmzone.h =================================================================== --- linux-2.6.orig/include/linux/mmzone.h +++ linux-2.6/include/linux/mmzone.h @@ -213,7 +213,7 @@ enum zone_type { struct zone { /* Fields commonly accessed by the page allocator */ - unsigned long pages_min, pages_low, pages_high; + unsigned long pages_emerg, pages_min, pages_low, pages_high; /* * We don't know if the memory that we're going to allocate will be freeable * or/and it will be released eventually, so to avoid totally wasting several @@ -682,6 +682,7 @@ int sysctl_min_unmapped_ratio_sysctl_han struct file *, void __user *, size_t *, loff_t *); int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *); +int adjust_memalloc_reserve(int pages); extern int numa_zonelist_order_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *); Index: linux-2.6/mm/page_alloc.c =================================================================== --- linux-2.6.orig/mm/page_alloc.c +++ linux-2.6/mm/page_alloc.c @@ -118,6 +118,8 @@ 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; unsigned long __meminitdata nr_kernel_pages; unsigned long __meminitdata nr_all_pages; @@ -1252,7 +1254,7 @@ int zone_watermark_ok(struct zone *z, in 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 0; for (o = 0; o < order; o++) { /* At the next order, this order's pages become unavailable */ @@ -1733,8 +1735,8 @@ nofail_alloc: nopage: if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) { printk(KERN_WARNING "%s: page allocation failure." - " order:%d, mode:0x%x\n", - p->comm, order, gfp_mask); + " order:%d, mode:0x%x, alloc_flags:0x%x, pflags:0x%x\n", + p->comm, order, gfp_mask, alloc_flags, p->flags); dump_stack(); show_mem(); } @@ -1952,9 +1954,9 @@ void show_free_areas(void) "\n", zone->name, K(zone_page_state(zone, NR_FREE_PAGES)), - K(zone->pages_min), - K(zone->pages_low), - K(zone->pages_high), + K(zone->pages_emerg + zone->pages_min), + K(zone->pages_emerg + zone->pages_low), + K(zone->pages_emerg + zone->pages_high), K(zone_page_state(zone, NR_ACTIVE)), K(zone_page_state(zone, NR_INACTIVE)), K(zone->present_pages), @@ -4113,7 +4115,7 @@ static void calculate_totalreserve_pages } /* we treat pages_high as reserved pages. */ - max += zone->pages_high; + max += zone->pages_high + zone->pages_emerg; if (max > zone->present_pages) max = zone->present_pages; @@ -4170,7 +4172,8 @@ static void setup_per_zone_lowmem_reserv */ static void __setup_per_zone_pages_min(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; @@ -4182,11 +4185,13 @@ static void __setup_per_zone_pages_min(v } for_each_zone(zone) { - u64 tmp; + u64 tmp, tmp_emerg; spin_lock_irqsave(&zone->lru_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 @@ -4205,12 +4210,14 @@ static void __setup_per_zone_pages_min(v if (min_pages > 128) min_pages = 128; zone->pages_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->pages_min = tmp; + zone->pages_emerg = tmp_emerg; } zone->pages_low = zone->pages_min + (tmp >> 2); @@ -4232,6 +4239,63 @@ void setup_per_zone_pages_min(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_pages_min(); +} + +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. * Index: linux-2.6/mm/vmstat.c =================================================================== --- linux-2.6.orig/mm/vmstat.c +++ linux-2.6/mm/vmstat.c @@ -752,9 +752,9 @@ static void zoneinfo_show_print(struct s "\n spanned %lu" "\n present %lu", zone_page_state(zone, NR_FREE_PAGES), - zone->pages_min, - zone->pages_low, - zone->pages_high, + zone->pages_emerg + zone->pages_min, + zone->pages_emerg + zone->pages_low, + zone->pages_emerg + zone->pages_high, zone->pages_scanned, zone->nr_scan_active, zone->nr_scan_inactive, zone->spanned_pages, -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/