[PATCH] Fix panic in __d_lookup with high dentry hashtable counts

From: Dimitri Sivanich
Date: Fri Jan 13 2012 - 10:52:45 EST


When the number of dentry cache hash table entries gets too high
(2147483648 entries), use of a signed integer in the initialization
loop prevents the dentry_hashtable from getting initialized, resulting
in a panic in __d_lookup. Fixing this in dcache_init and a few other
spots for consistency.

Signed-off-by: Dimitri Sivanich <sivanich@xxxxxxx>
---
fs/dcache.c | 8 ++++----
fs/inode.c | 8 ++++----
kernel/pid.c | 4 ++--
net/ipv4/tcp.c | 3 ++-
4 files changed, 12 insertions(+), 11 deletions(-)

Index: linux/fs/dcache.c
===================================================================
--- linux.orig/fs/dcache.c
+++ linux/fs/dcache.c
@@ -2968,7 +2968,7 @@ __setup("dhash_entries=", set_dhash_entr

static void __init dcache_init_early(void)
{
- int loop;
+ long loop;

/* If hashes are distributed across NUMA nodes, defer
* hash allocation until vmalloc space is available.
@@ -2986,13 +2986,13 @@ static void __init dcache_init_early(voi
&d_hash_mask,
0);

- for (loop = 0; loop < (1 << d_hash_shift); loop++)
+ for (loop = 0; loop < (1L << d_hash_shift); loop++)
INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
}

static void __init dcache_init(void)
{
- int loop;
+ long loop;

/*
* A constructor could be added for stable state like the lists,
@@ -3016,7 +3016,7 @@ static void __init dcache_init(void)
&d_hash_mask,
0);

- for (loop = 0; loop < (1 << d_hash_shift); loop++)
+ for (loop = 0; loop < (1L << d_hash_shift); loop++)
INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
}

Index: linux/fs/inode.c
===================================================================
--- linux.orig/fs/inode.c
+++ linux/fs/inode.c
@@ -1654,7 +1654,7 @@ __setup("ihash_entries=", set_ihash_entr
*/
void __init inode_init_early(void)
{
- int loop;
+ long loop;

/* If hashes are distributed across NUMA nodes, defer
* hash allocation until vmalloc space is available.
@@ -1672,13 +1672,13 @@ void __init inode_init_early(void)
&i_hash_mask,
0);

- for (loop = 0; loop < (1 << i_hash_shift); loop++)
+ for (loop = 0; loop < (1L << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}

void __init inode_init(void)
{
- int loop;
+ long loop;

/* inode slab cache */
inode_cachep = kmem_cache_create("inode_cache",
@@ -1702,7 +1702,7 @@ void __init inode_init(void)
&i_hash_mask,
0);

- for (loop = 0; loop < (1 << i_hash_shift); loop++)
+ for (loop = 0; loop < (1L << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}

Index: linux/kernel/pid.c
===================================================================
--- linux.orig/kernel/pid.c
+++ linux/kernel/pid.c
@@ -543,12 +543,12 @@ struct pid *find_ge_pid(int nr, struct p
*/
void __init pidhash_init(void)
{
- int i, pidhash_size;
+ long i, pidhash_size;

pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
HASH_EARLY | HASH_SMALL,
&pidhash_shift, NULL, 4096);
- pidhash_size = 1 << pidhash_shift;
+ pidhash_size = 1L << pidhash_shift;

for (i = 0; i < pidhash_size; i++)
INIT_HLIST_HEAD(&pid_hash[i]);
Index: linux/net/ipv4/tcp.c
===================================================================
--- linux.orig/net/ipv4/tcp.c
+++ linux/net/ipv4/tcp.c
@@ -3220,7 +3220,8 @@ void __init tcp_init(void)
{
struct sk_buff *skb = NULL;
unsigned long limit;
- int i, max_share, cnt;
+ long i;
+ int max_share, cnt;
unsigned long jiffy = jiffies;

BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
--
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