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![Tim Chen](/assets/img/avatar_default.png)
Currently the per cpu counter's batch size for memory accounting is configured as twice the number of cpus in the system. However, for system with very large memory, it is more appropriate to make it proportional to the memory size per cpu in the system. For example, for a x86_64 system with 64 cpus and 128 GB of memory, the batch size is only 2*64 pages (0.5 MB). So any memory accounting changes of more than 0.5MB will overflow the per cpu counter into the global counter. Instead, for the new scheme, the batch size is configured to be 0.4% of the memory/cpu = 8MB (128 GB/64 /256), which is more inline with the memory size. I've done a repeated brk test of 800KB (from will-it-scale test suite) with 80 concurrent processes on a 4 socket Westmere machine with a total of 40 cores. Without the patch, about 80% of cpu is spent on spin-lock contention within the vm_committed_as counter. With the patch, there's a 73x speedup on the benchmark and the lock contention drops off almost entirely. [akpm@linux-foundation.org: fix section mismatch] Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Tejun Heo <tj@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
206 lines
5 KiB
C
206 lines
5 KiB
C
/*
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* mm_init.c - Memory initialisation verification and debugging
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*
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* Copyright 2008 IBM Corporation, 2008
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* Author Mel Gorman <mel@csn.ul.ie>
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*
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/kobject.h>
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#include <linux/export.h>
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#include <linux/memory.h>
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#include <linux/notifier.h>
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#include "internal.h"
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#ifdef CONFIG_DEBUG_MEMORY_INIT
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int mminit_loglevel;
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#ifndef SECTIONS_SHIFT
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#define SECTIONS_SHIFT 0
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#endif
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/* The zonelists are simply reported, validation is manual. */
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void mminit_verify_zonelist(void)
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{
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int nid;
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if (mminit_loglevel < MMINIT_VERIFY)
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return;
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for_each_online_node(nid) {
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pg_data_t *pgdat = NODE_DATA(nid);
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struct zone *zone;
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struct zoneref *z;
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struct zonelist *zonelist;
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int i, listid, zoneid;
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BUG_ON(MAX_ZONELISTS > 2);
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for (i = 0; i < MAX_ZONELISTS * MAX_NR_ZONES; i++) {
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/* Identify the zone and nodelist */
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zoneid = i % MAX_NR_ZONES;
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listid = i / MAX_NR_ZONES;
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zonelist = &pgdat->node_zonelists[listid];
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zone = &pgdat->node_zones[zoneid];
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if (!populated_zone(zone))
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continue;
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/* Print information about the zonelist */
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printk(KERN_DEBUG "mminit::zonelist %s %d:%s = ",
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listid > 0 ? "thisnode" : "general", nid,
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zone->name);
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/* Iterate the zonelist */
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for_each_zone_zonelist(zone, z, zonelist, zoneid) {
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#ifdef CONFIG_NUMA
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printk(KERN_CONT "%d:%s ",
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zone->node, zone->name);
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#else
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printk(KERN_CONT "0:%s ", zone->name);
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#endif /* CONFIG_NUMA */
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}
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printk(KERN_CONT "\n");
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}
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}
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}
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void __init mminit_verify_pageflags_layout(void)
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{
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int shift, width;
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unsigned long or_mask, add_mask;
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shift = 8 * sizeof(unsigned long);
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width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH - LAST_NID_SHIFT;
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths",
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"Section %d Node %d Zone %d Lastnid %d Flags %d\n",
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SECTIONS_WIDTH,
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NODES_WIDTH,
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ZONES_WIDTH,
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LAST_NID_WIDTH,
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NR_PAGEFLAGS);
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
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"Section %d Node %d Zone %d Lastnid %d\n",
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SECTIONS_SHIFT,
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NODES_SHIFT,
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ZONES_SHIFT,
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LAST_NID_SHIFT);
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_pgshifts",
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"Section %lu Node %lu Zone %lu Lastnid %lu\n",
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(unsigned long)SECTIONS_PGSHIFT,
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(unsigned long)NODES_PGSHIFT,
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(unsigned long)ZONES_PGSHIFT,
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(unsigned long)LAST_NID_PGSHIFT);
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodezoneid",
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"Node/Zone ID: %lu -> %lu\n",
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(unsigned long)(ZONEID_PGOFF + ZONEID_SHIFT),
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(unsigned long)ZONEID_PGOFF);
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_usage",
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"location: %d -> %d layout %d -> %d unused %d -> %d page-flags\n",
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shift, width, width, NR_PAGEFLAGS, NR_PAGEFLAGS, 0);
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#ifdef NODE_NOT_IN_PAGE_FLAGS
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodeflags",
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"Node not in page flags");
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#endif
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#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
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mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodeflags",
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"Last nid not in page flags");
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#endif
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if (SECTIONS_WIDTH) {
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shift -= SECTIONS_WIDTH;
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BUG_ON(shift != SECTIONS_PGSHIFT);
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}
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if (NODES_WIDTH) {
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shift -= NODES_WIDTH;
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BUG_ON(shift != NODES_PGSHIFT);
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}
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if (ZONES_WIDTH) {
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shift -= ZONES_WIDTH;
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BUG_ON(shift != ZONES_PGSHIFT);
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}
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/* Check for bitmask overlaps */
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or_mask = (ZONES_MASK << ZONES_PGSHIFT) |
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(NODES_MASK << NODES_PGSHIFT) |
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(SECTIONS_MASK << SECTIONS_PGSHIFT);
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add_mask = (ZONES_MASK << ZONES_PGSHIFT) +
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(NODES_MASK << NODES_PGSHIFT) +
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(SECTIONS_MASK << SECTIONS_PGSHIFT);
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BUG_ON(or_mask != add_mask);
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}
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void __meminit mminit_verify_page_links(struct page *page, enum zone_type zone,
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unsigned long nid, unsigned long pfn)
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{
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BUG_ON(page_to_nid(page) != nid);
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BUG_ON(page_zonenum(page) != zone);
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BUG_ON(page_to_pfn(page) != pfn);
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}
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static __init int set_mminit_loglevel(char *str)
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{
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get_option(&str, &mminit_loglevel);
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return 0;
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}
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early_param("mminit_loglevel", set_mminit_loglevel);
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#endif /* CONFIG_DEBUG_MEMORY_INIT */
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struct kobject *mm_kobj;
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EXPORT_SYMBOL_GPL(mm_kobj);
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#ifdef CONFIG_SMP
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s32 vm_committed_as_batch = 32;
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static void __meminit mm_compute_batch(void)
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{
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u64 memsized_batch;
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s32 nr = num_present_cpus();
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s32 batch = max_t(s32, nr*2, 32);
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/* batch size set to 0.4% of (total memory/#cpus), or max int32 */
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memsized_batch = min_t(u64, (totalram_pages/nr)/256, 0x7fffffff);
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vm_committed_as_batch = max_t(s32, memsized_batch, batch);
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}
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static int __meminit mm_compute_batch_notifier(struct notifier_block *self,
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unsigned long action, void *arg)
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{
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switch (action) {
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case MEM_ONLINE:
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case MEM_OFFLINE:
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mm_compute_batch();
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default:
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block compute_batch_nb __meminitdata = {
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.notifier_call = mm_compute_batch_notifier,
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.priority = IPC_CALLBACK_PRI, /* use lowest priority */
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};
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static int __init mm_compute_batch_init(void)
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{
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mm_compute_batch();
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register_hotmemory_notifier(&compute_batch_nb);
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return 0;
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}
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__initcall(mm_compute_batch_init);
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#endif
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static int __init mm_sysfs_init(void)
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{
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mm_kobj = kobject_create_and_add("mm", kernel_kobj);
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if (!mm_kobj)
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return -ENOMEM;
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return 0;
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}
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__initcall(mm_sysfs_init);
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