Re: [Bug 32772] New: PROBLEM: kernel BUG at net/ipv4/inetpeer.c:386

David Miller
2011-04-13T20:24:39Z

From: Dmitry Novikov <dimetrios@gmail.com>
Date: Wed, 13 Apr 2011 23:14:03 +0300

> Crash again after 7 days of uptime. slub_nomerge is set

Looks like too deep stack, try this patch which is in net-2.6:

--------------------
inetpeer: reduce stack usage

On 64bit arches, we use 752 bytes of stack when cleanup_once() is called
from inet_getpeer().

Lets share the avl stack to save ~376 bytes.

Before patch :

# objdump -d net/ipv4/inetpeer.o | scripts/checkstack.pl

0x000006c3 unlink_from_pool [inetpeer.o]: 376
0x00000721 unlink_from_pool [inetpeer.o]: 376
0x00000cb1 inet_getpeer [inetpeer.o]: 376
0x00000e6d inet_getpeer [inetpeer.o]: 376
0x0004 inet_initpeers [inetpeer.o]: 112
# size net/ipv4/inetpeer.o
text data bss dec hex filename
5320 432 21 5773 168d net/ipv4/inetpeer.o

After patch :

objdump -d net/ipv4/inetpeer.o | scripts/checkstack.pl
0x00000c11 inet_getpeer [inetpeer.o]: 376
0x00000dcd inet_getpeer [inetpeer.o]: 376
0x00000ab9 peer_check_expire [inetpeer.o]: 328
0x00000b7f peer_check_expire [inetpeer.o]: 328
0x0004 inet_initpeers [inetpeer.o]: 112
# size net/ipv4/inetpeer.o
text data bss dec hex filename
5163 432 21 5616 15f0 net/ipv4/inetpeer.o

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Scot Doyle <lkml@scotdoyle.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Reviewed-by: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/inetpeer.c | 13 +++++++------
1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index dd1b20e..9df4e63 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -354,7 +354,8 @@ static void inetpeer_free_rcu(struct rcu_head *head)
}

/* May be called with local BH enabled. */
-static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base)
+static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base,
+ struct inet_peer __rcu **stack[PEER_MAXDEPTH])
{
int do_free;

@@ -368,7 +369,6 @@ static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base)
* We use refcnt=-1 to alert lockless readers this entry is deleted.
*/
if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) {
- struct inet_peer __rcu **stack[PEER_MAXDEPTH];
struct inet_peer __rcu ***stackptr, ***delp;
if (lookup(&p->daddr, stack, base) != p)
BUG();
@@ -422,7 +422,7 @@ static struct inet_peer_base *peer_to_base(struct inet_peer *p)
}

/* May be called with local BH enabled. */
-static int cleanup_once(unsigned long ttl)
+static int cleanup_once(unsigned long ttl, struct inet_peer __rcu **stack[PEER_MAXDEPTH])
{
struct inet_peer *p = NULL;

@@ -454,7 +454,7 @@ static int cleanup_once(unsigned long ttl)
* happen because of entry limits in route cache. */
return -1;

- unlink_from_pool(p, peer_to_base(p));
+ unlink_from_pool(p, peer_to_base(p), stack);
return 0;
}

@@ -524,7 +524,7 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create)

if (base->total >= inet_peer_threshold)
/* Remove one less-recently-used entry. */
- cleanup_once(0);
+ cleanup_once(0, stack);

return p;
}
@@ -540,6 +540,7 @@ static void peer_check_expire(unsigned long dummy)
{
unsigned long now = jiffies;
int ttl, total;
+ struct inet_peer __rcu **stack[PEER_MAXDEPTH];

total = compute_total();
if (total >= inet_peer_threshold)
@@ -548,7 +549,7 @@ static void peer_check_expire(unsigned long dummy)
ttl = inet_peer_maxttl
- (inet_peer_maxttl - inet_peer_minttl) / HZ *
total / inet_peer_threshold * HZ;
- while (!cleanup_once(ttl)) {
+ while (!cleanup_once(ttl, stack)) {
if (jiffies != now)
break;
}
--
1.7.4.3