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Date: Tue, 17 Jan 2012 15:05:41 -0600
From: Dimitri Sivanich <sivanich@....com>
To: David Miller <davem@...emloft.net>
Cc: linux-kernel@...r.kernel.org, viro@...IV.linux.org.uk,
eric.dumazet@...il.com, kuznet@....inr.ac.ru, jmorris@...ei.org,
yoshfuji@...ux-ipv6.org, kaber@...sh.net,
paulmck@...ux.vnet.ibm.com, paul.gortmaker@...driver.com,
akpm@...ux-foundation.org, jkosina@...e.cz, avi@...hat.com,
linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] Fix panic in __d_lookup with high dentry hashtable
counts
On Tue, Jan 17, 2012 at 12:22:29PM -0500, David Miller wrote:
> To be honest I think this is overkill.
>
> Supporting anything larger than a 32-bit hash mask is not even close
> to being reasonable. Nobody needs a 4GB hash table, not for anything.
>
Here is a patch that keeps the 32-bit hash mask.
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(). Fix this in dcache_init() and similar areas.
Signed-off-by: Dimitri Sivanich <sivanich@....com>
---
fs/dcache.c | 8 ++++----
fs/inode.c | 8 ++++----
kernel/pid.c | 4 ++--
mm/page_alloc.c | 1 +
net/ipv4/tcp.c | 5 +++--
5 files changed, 14 insertions(+), 12 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;
+ unsigned int 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 < (1U << d_hash_shift); loop++)
INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
}
static void __init dcache_init(void)
{
- int loop;
+ unsigned int 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 < (1U << 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;
+ unsigned int 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 < (1U << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}
void __init inode_init(void)
{
- int loop;
+ unsigned int 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 < (1U << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}
Index: linux/mm/page_alloc.c
===================================================================
--- linux.orig/mm/page_alloc.c
+++ linux/mm/page_alloc.c
@@ -5258,6 +5258,7 @@ void *__init alloc_large_system_hash(con
max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
do_div(max, bucketsize);
}
+ max = min(max, 0x80000000ULL);
if (numentries > max)
numentries = max;
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;
+ unsigned int 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 = 1U << 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;
+ int max_share, cnt;
+ unsigned int i;
unsigned long jiffy = jiffies;
BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
@@ -3263,7 +3264,7 @@ void __init tcp_init(void)
&tcp_hashinfo.bhash_size,
NULL,
64 * 1024);
- tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
+ tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
spin_lock_init(&tcp_hashinfo.bhash[i].lock);
INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
--
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