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Subject[PATCH] Fix panic in __d_lookup with high dentry hashtable counts
When the number of dentry cache hash table entries gets too high
(2147483648 entries), as happens by default on a 16TB system, use
of a signed integer in the dcache_init() initialization loop prevents
the dentry_hashtable from getting initialized, causing a panic in
__d_lookup().

In addition, the _hash_mask returned from alloc_large_system_hash() does
not support more than a 32 bit hash table size.

Changing the _hash_mask size returned from alloc_large_system_hash() to
support larger hash table sizes in the future, and changing loop counter
sizes appropriately.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
---
fs/dcache.c | 10 +++++-----
fs/inode.c | 10 +++++-----
include/linux/bootmem.h | 2 +-
mm/page_alloc.c | 2 +-
net/ipv4/route.c | 8 ++++++--
net/ipv4/tcp.c | 13 +++++++++----
net/ipv4/udp.c | 5 ++++-
7 files changed, 31 insertions(+), 19 deletions(-)
Index: linux/fs/dcache.c
===================================================================
--- linux.orig/fs/dcache.c
+++ linux/fs/dcache.c
@@ -99,7 +99,7 @@ static struct kmem_cache *dentry_cache _
#define D_HASHBITS d_hash_shift
#define D_HASHMASK d_hash_mask

-static unsigned int d_hash_mask __read_mostly;
+static unsigned long d_hash_mask __read_mostly;
static unsigned int d_hash_shift __read_mostly;

static struct hlist_bl_head *dentry_hashtable __read_mostly;
@@ -2968,7 +2968,7 @@ __setup("dhash_entries=", set_dhash_entr

static void __init dcache_init_early(void)
{
- int loop;
+ unsigned 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 < (1UL << d_hash_shift); loop++)
INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
}

static void __init dcache_init(void)
{
- int loop;
+ unsigned 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 < (1UL << 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
@@ -60,7 +60,7 @@
* inode_hash_lock
*/

-static unsigned int i_hash_mask __read_mostly;
+static unsigned long i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;
static struct hlist_head *inode_hashtable __read_mostly;
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
@@ -1654,7 +1654,7 @@ __setup("ihash_entries=", set_ihash_entr
*/
void __init inode_init_early(void)
{
- int loop;
+ unsigned 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 < (1UL << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}

void __init inode_init(void)
{
- int loop;
+ unsigned 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 < (1UL << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}

Index: linux/include/linux/bootmem.h
===================================================================
--- linux.orig/include/linux/bootmem.h
+++ linux/include/linux/bootmem.h
@@ -153,7 +153,7 @@ extern void *alloc_large_system_hash(con
int scale,
int flags,
unsigned int *_hash_shift,
- unsigned int *_hash_mask,
+ unsigned long *_hash_mask,
unsigned long limit);

#define HASH_EARLY 0x00000001 /* Allocating during early boot? */
Index: linux/mm/page_alloc.c
===================================================================
--- linux.orig/mm/page_alloc.c
+++ linux/mm/page_alloc.c
@@ -5219,7 +5219,7 @@ void *__init alloc_large_system_hash(con
int scale,
int flags,
unsigned int *_hash_shift,
- unsigned int *_hash_mask,
+ unsigned long *_hash_mask,
unsigned long limit)
{
unsigned long long max = limit;
Index: linux/net/ipv4/route.c
===================================================================
--- linux.orig/net/ipv4/route.c
+++ linux/net/ipv4/route.c
@@ -3446,6 +3446,7 @@ __setup("rhash_entries=", set_rhash_entr

int __init ip_rt_init(void)
{
+ unsigned long hash_mask;
int rc = 0;

#ifdef CONFIG_IP_ROUTE_CLASSID
@@ -3474,8 +3475,11 @@ int __init ip_rt_init(void)
15 : 17,
0,
&rt_hash_log,
- &rt_hash_mask,
- rhash_entries ? 0 : 512 * 1024);
+ &hash_mask,
+ rhash_entries ? 0x80000000 :
+ 512 * 1024);
+ /* FIXME: Above limit value (0x80000000) allows the following cast. */
+ rt_hash_mask = (unsigned int) hash_mask;
memset(rt_hash_table, 0, (rt_hash_mask + 1) * sizeof(struct rt_hash_bucket));
rt_hash_lock_init();

Index: linux/net/ipv4/tcp.c
===================================================================
--- linux.orig/net/ipv4/tcp.c
+++ linux/net/ipv4/tcp.c
@@ -3219,8 +3219,9 @@ __setup("thash_entries=", set_thash_entr
void __init tcp_init(void)
{
struct sk_buff *skb = NULL;
- unsigned long limit;
- int i, max_share, cnt;
+ unsigned long limit, hash_mask;
+ unsigned i;
+ int max_share, cnt;
unsigned long jiffy = jiffies;

BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
@@ -3245,8 +3246,12 @@ void __init tcp_init(void)
13 : 15,
0,
NULL,
- &tcp_hashinfo.ehash_mask,
- thash_entries ? 0 : 512 * 1024);
+ &hash_mask,
+ thash_entries ? 0x80000000 :
+ 512 * 1024);
+ /* FIXME: Above limit value (0x80000000) allows the following cast. */
+ tcp_hashinfo.ehash_mask = (unsigned int)hash_mask;
+
for (i = 0; i <= tcp_hashinfo.ehash_mask; i++) {
INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
Index: linux/net/ipv4/udp.c
===================================================================
--- linux.orig/net/ipv4/udp.c
+++ linux/net/ipv4/udp.c
@@ -2180,6 +2180,7 @@ __setup("uhash_entries=", set_uhash_entr

void __init udp_table_init(struct udp_table *table, const char *name)
{
+ unsigned long hash_mask;
unsigned int i;

if (!CONFIG_BASE_SMALL)
@@ -2189,8 +2190,10 @@ void __init udp_table_init(struct udp_ta
21, /* one slot per 2 MB */
0,
&table->log,
- &table->mask,
+ &hash_mask,
64 * 1024);
+ /* FIXME: Above limit value (64 * 1024) allows the following cast. */
+ table->mask = (unsigned int)hash_mask;
/*
* Make sure hash table has the minimum size
*/

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