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Revision d1908362ae0b97374eb8328fbb471576332f9fb1 authored by Minchan Kim on 22 September 2010, 20:05:01 UTC, committed by Linus Torvalds on 23 September 2010, 00:22:39 UTC 
vmscan: check all_unreclaimable in direct reclaim path
 
M.  Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his
32bit 3GB mem machine.
(https://bugzilla.kernel.org/show_bug.cgi?id=16771). Also he bisected
the regression to

  commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c
  Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
  Date:   Fri Jun 4 14:15:05 2010 -0700

     vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure

At first impression, this seemed very strange because the above commit
only chenged function return value and hibernate_preallocate_memory()
ignore return value of shrink_all_memory().  But it's related.

Now, page allocation from hibernation code may enter infinite loop if the
system has highmem.  The reasons are that vmscan don't care enough OOM
case when oom_killer_disabled.

The problem sequence is following as.

1. hibernation
2. oom_disable
3. alloc_pages
4. do_try_to_free_pages
       if (scanning_global_lru(sc) && !all_unreclaimable)
               return 1;

If kswapd is not freozen, it would set zone->all_unreclaimable to 1 and
then shrink_zones maybe return true(ie, all_unreclaimable is true).  So at
last, alloc_pages could go to _nopage_.  If it is, it should have no
problem.

This patch adds all_unreclaimable check to protect in direct reclaim path,
too.  It can care of hibernation OOM case and help bailout
all_unreclaimable case slightly.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reported-by: M. Vefa Bicakci <bicave@superonline.com>
Reported-by: <caiqian@redhat.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: <caiqian@redhat.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent eba93fc
Raw File
sysctl_net.c 
/* -*- linux-c -*-
 * sysctl_net.c: sysctl interface to net subsystem.
 *
 * Begun April 1, 1996, Mike Shaver.
 * Added /proc/sys/net directories for each protocol family. [MS]
 *
 * Revision 1.2  1996/05/08  20:24:40  shaver
 * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
 * NET_IPV4_IP_FORWARD.
 *
 *
 */

#include <linux/mm.h>
#include <linux/sysctl.h>
#include <linux/nsproxy.h>

#include <net/sock.h>

#ifdef CONFIG_INET
#include <net/ip.h>
#endif

#ifdef CONFIG_NET
#include <linux/if_ether.h>
#endif

#ifdef CONFIG_TR
#include <linux/if_tr.h>
#endif

static struct ctl_table_set *
net_ctl_header_lookup(struct ctl_table_root *root, struct nsproxy *namespaces)
{
	return &namespaces->net_ns->sysctls;
}

static int is_seen(struct ctl_table_set *set)
{
	return &current->nsproxy->net_ns->sysctls == set;
}

/* Return standard mode bits for table entry. */
static int net_ctl_permissions(struct ctl_table_root *root,
			       struct nsproxy *nsproxy,
			       struct ctl_table *table)
{
	/* Allow network administrator to have same access as root. */
	if (capable(CAP_NET_ADMIN)) {
		int mode = (table->mode >> 6) & 7;
		return (mode << 6) | (mode << 3) | mode;
	}
	return table->mode;
}

static struct ctl_table_root net_sysctl_root = {
	.lookup = net_ctl_header_lookup,
	.permissions = net_ctl_permissions,
};

static int net_ctl_ro_header_perms(struct ctl_table_root *root,
		struct nsproxy *namespaces, struct ctl_table *table)
{
	if (net_eq(namespaces->net_ns, &init_net))
		return table->mode;
	else
		return table->mode & ~0222;
}

static struct ctl_table_root net_sysctl_ro_root = {
	.permissions = net_ctl_ro_header_perms,
};

static int __net_init sysctl_net_init(struct net *net)
{
	setup_sysctl_set(&net->sysctls,
			 &net_sysctl_ro_root.default_set,
			 is_seen);
	return 0;
}

static void __net_exit sysctl_net_exit(struct net *net)
{
	WARN_ON(!list_empty(&net->sysctls.list));
}

static struct pernet_operations sysctl_pernet_ops = {
	.init = sysctl_net_init,
	.exit = sysctl_net_exit,
};

static __init int sysctl_init(void)
{
	int ret;
	ret = register_pernet_subsys(&sysctl_pernet_ops);
	if (ret)
		goto out;
	register_sysctl_root(&net_sysctl_root);
	setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL, NULL);
	register_sysctl_root(&net_sysctl_ro_root);
out:
	return ret;
}
subsys_initcall(sysctl_init);

struct ctl_table_header *register_net_sysctl_table(struct net *net,
	const struct ctl_path *path, struct ctl_table *table)
{
	struct nsproxy namespaces;
	namespaces = *current->nsproxy;
	namespaces.net_ns = net;
	return __register_sysctl_paths(&net_sysctl_root,
					&namespaces, path, table);
}
EXPORT_SYMBOL_GPL(register_net_sysctl_table);

struct ctl_table_header *register_net_sysctl_rotable(const
		struct ctl_path *path, struct ctl_table *table)
{
	return __register_sysctl_paths(&net_sysctl_ro_root,
			&init_nsproxy, path, table);
}
EXPORT_SYMBOL_GPL(register_net_sysctl_rotable);

void unregister_net_sysctl_table(struct ctl_table_header *header)
{
	unregister_sysctl_table(header);
}
EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);
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