mem-hotplug: fix potential race while building zonelist for new populated zone
Add global mutex zonelists_mutex to fix the possible race: CPU0 CPU1 CPU2 (1) zone->present_pages += online_pages; (2) build_all_zonelists(); (3) alloc_page(); (4) free_page(); (5) build_all_zonelists(); (6) __build_all_zonelists(); (7) zone->pageset = alloc_percpu(); In step (3,4), zone->pageset still points to boot_pageset, so bad things may happen if 2+ nodes are in this state. Even if only 1 node is accessing the boot_pageset, (3) may still consume too much memory to fail the memory allocations in step (7). Besides, atomic operation ensures alloc_percpu() in step (7) will never fail since there is a new fresh memory block added in step(6). [haicheng.li@linux.intel.com: hold zonelists_mutex when build_all_zonelists] Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Andi Kleen <andi.kleen@intel.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Родитель
1f522509c7
Коммит
4eaf3f6439
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@ -650,6 +650,7 @@ typedef struct pglist_data {
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#include <linux/memory_hotplug.h>
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extern struct mutex zonelists_mutex;
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void get_zone_counts(unsigned long *active, unsigned long *inactive,
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unsigned long *free);
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void build_all_zonelists(void *data);
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@ -357,8 +357,11 @@ int __cpuinit cpu_up(unsigned int cpu)
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return -ENOMEM;
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}
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if (pgdat->node_zonelists->_zonerefs->zone == NULL)
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if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
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mutex_lock(&zonelists_mutex);
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build_all_zonelists(NULL);
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mutex_unlock(&zonelists_mutex);
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}
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#endif
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cpu_maps_update_begin();
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@ -389,11 +389,6 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
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int nid;
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int ret;
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struct memory_notify arg;
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/*
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* mutex to protect zone->pageset when it's still shared
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* in onlined_pages()
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*/
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static DEFINE_MUTEX(zone_pageset_mutex);
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arg.start_pfn = pfn;
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arg.nr_pages = nr_pages;
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@ -420,14 +415,14 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
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* This means the page allocator ignores this zone.
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* So, zonelist must be updated after online.
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*/
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mutex_lock(&zone_pageset_mutex);
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mutex_lock(&zonelists_mutex);
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if (!populated_zone(zone))
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need_zonelists_rebuild = 1;
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ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
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online_pages_range);
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if (ret) {
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mutex_unlock(&zone_pageset_mutex);
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mutex_unlock(&zonelists_mutex);
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printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
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nr_pages, pfn);
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memory_notify(MEM_CANCEL_ONLINE, &arg);
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@ -441,7 +436,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
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else
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zone_pcp_update(zone);
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mutex_unlock(&zone_pageset_mutex);
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mutex_unlock(&zonelists_mutex);
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setup_per_zone_wmarks();
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calculate_zone_inactive_ratio(zone);
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if (onlined_pages) {
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@ -2571,8 +2571,11 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
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strncpy((char*)table->data, saved_string,
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NUMA_ZONELIST_ORDER_LEN);
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user_zonelist_order = oldval;
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} else if (oldval != user_zonelist_order)
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} else if (oldval != user_zonelist_order) {
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mutex_lock(&zonelists_mutex);
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build_all_zonelists(NULL);
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mutex_unlock(&zonelists_mutex);
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}
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}
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out:
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mutex_unlock(&zl_order_mutex);
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@ -2924,6 +2927,12 @@ static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
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static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
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static void setup_zone_pageset(struct zone *zone);
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/*
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* Global mutex to protect against size modification of zonelists
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* as well as to serialize pageset setup for the new populated zone.
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*/
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DEFINE_MUTEX(zonelists_mutex);
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/* return values int ....just for stop_machine() */
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static __init_refok int __build_all_zonelists(void *data)
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{
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@ -2967,6 +2976,10 @@ static __init_refok int __build_all_zonelists(void *data)
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return 0;
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}
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/*
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* Called with zonelists_mutex held always
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* unless system_state == SYSTEM_BOOTING.
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*/
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void build_all_zonelists(void *data)
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{
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set_zonelist_order();
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