Messages in this thread Patch in this message | | | Subject | Re: RFC: memory leak in udp_table_init | From | Eric Dumazet <> | Date | Sat, 25 Feb 2012 06:19:42 +0100 |
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Le vendredi 24 février 2012 à 20:27 -0500, Paul Gortmaker a écrit : > On Fri, Feb 24, 2012 at 7:55 PM, Tim Bird <tim.bird@am.sony.com> wrote: > > We've uncovered an obscure memory leak in the routine udp_table_init(), > > in the file: net/ipv4/udp.c > > At a glance, I think what you are seeing is the same as this? > > http://lists.openwall.net/netdev/2011/06/22/12 >
Yes, this issue is somewhat recurrent...
> > Any suggestions for a way to correct for a too-small first allocation, without > > a memory leak? > > > > Alternatively - how critical is this UDP_HTABLE_SIZE_MIN for correct operation > > of the stack?
Absolutely mandatory, if you read net/ipv4/udp.c
Lets add a new parameter to alloc_large_system_hash() to specify minimum number of slots in hash table.
David, this patch is based on Linus tree, not on net tree. (Doesnt apply properly on net tree currently)
Thanks
[PATCH] mm: add a low limit to alloc_large_system_hash
UDP stack needs a minimum hash size value for proper operation and also uses alloc_large_system_hash() for proper NUMA distribution of its hash tables and automatic sizing depending on available system memory.
On some low memory situations, udp_table_init() must ignore the alloc_large_system_hash() result and reallocs a bigger memory area.
As we cannot easily free old hash table, we leak it and kmemleak can issue a warning.
This patch adds a low limit parameter to alloc_large_system_hash() to solve this problem.
We then specify UDP_HTABLE_SIZE_MIN for UDP/UDPLite hash table allocation, and 16 for pid_hash.
Reported-by: Mark Asselstine <mark.asselstine@windriver.com> Reported-by: Tim Bird <tim.bird@am.sony.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> --- fs/dcache.c | 2 ++ fs/inode.c | 2 ++ include/linux/bootmem.h | 3 ++- kernel/pid.c | 3 ++- mm/page_alloc.c | 7 +++++-- net/ipv4/route.c | 1 + net/ipv4/tcp.c | 2 ++ net/ipv4/udp.c | 30 ++++++++++-------------------- 8 files changed, 26 insertions(+), 24 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c index fe19ac1..ef5e72e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2984,6 +2984,7 @@ static void __init dcache_init_early(void) HASH_EARLY, &d_hash_shift, &d_hash_mask, + 0, 0); for (loop = 0; loop < (1U << d_hash_shift); loop++) @@ -3014,6 +3015,7 @@ static void __init dcache_init(void) 0, &d_hash_shift, &d_hash_mask, + 0, 0); for (loop = 0; loop < (1U << d_hash_shift); loop++) diff --git a/fs/inode.c b/fs/inode.c index d3ebdbe..7acee4c 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1667,6 +1667,7 @@ void __init inode_init_early(void) HASH_EARLY, &i_hash_shift, &i_hash_mask, + 0, 0); for (loop = 0; loop < (1U << i_hash_shift); loop++) @@ -1697,6 +1698,7 @@ void __init inode_init(void) 0, &i_hash_shift, &i_hash_mask, + 0, 0); for (loop = 0; loop < (1U << i_hash_shift); loop++) diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h index 66d3e95..1a0cd27 100644 --- a/include/linux/bootmem.h +++ b/include/linux/bootmem.h @@ -154,7 +154,8 @@ extern void *alloc_large_system_hash(const char *tablename, int flags, unsigned int *_hash_shift, unsigned int *_hash_mask, - unsigned long limit); + unsigned long low_limit, + unsigned long high_limit); #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ #define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min diff --git a/kernel/pid.c b/kernel/pid.c index 9f08dfa..79884b2 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -547,7 +547,8 @@ void __init pidhash_init(void) pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18, HASH_EARLY | HASH_SMALL, - &pidhash_shift, NULL, 4096); + &pidhash_shift, NULL, + 16, 4096); pidhash_size = 1U << pidhash_shift; for (i = 0; i < pidhash_size; i++) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index a13ded1..f037398 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5198,9 +5198,10 @@ void *__init alloc_large_system_hash(const char *tablename, int flags, unsigned int *_hash_shift, unsigned int *_hash_mask, - unsigned long limit) + unsigned long low_limit, + unsigned long high_limit) { - unsigned long long max = limit; + unsigned long long max = high_limit; unsigned long log2qty, size; void *table = NULL; @@ -5238,6 +5239,8 @@ void *__init alloc_large_system_hash(const char *tablename, } max = min(max, 0x80000000ULL); + if (numentries < low_limit) + numentries = low_limit; if (numentries > max) numentries = max; diff --git a/net/ipv4/route.c b/net/ipv4/route.c index bcacf54..0a41e38 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -3475,6 +3475,7 @@ int __init ip_rt_init(void) 0, &rt_hash_log, &rt_hash_mask, + 0, rhash_entries ? 0 : 512 * 1024); memset(rt_hash_table, 0, (rt_hash_mask + 1) * sizeof(struct rt_hash_bucket)); rt_hash_lock_init(); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 22ef5f9..e61a498 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3267,6 +3267,7 @@ void __init tcp_init(void) 0, NULL, &tcp_hashinfo.ehash_mask, + 0, thash_entries ? 0 : 512 * 1024); for (i = 0; i <= tcp_hashinfo.ehash_mask; i++) { INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i); @@ -3283,6 +3284,7 @@ void __init tcp_init(void) 0, &tcp_hashinfo.bhash_size, NULL, + 0, 64 * 1024); tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size; for (i = 0; i < tcp_hashinfo.bhash_size; i++) { diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 5d075b5..dc68ed2 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2182,26 +2182,16 @@ void __init udp_table_init(struct udp_table *table, const char *name) { unsigned int i; - if (!CONFIG_BASE_SMALL) - table->hash = alloc_large_system_hash(name, - 2 * sizeof(struct udp_hslot), - uhash_entries, - 21, /* one slot per 2 MB */ - 0, - &table->log, - &table->mask, - 64 * 1024); - /* - * Make sure hash table has the minimum size - */ - if (CONFIG_BASE_SMALL || table->mask < UDP_HTABLE_SIZE_MIN - 1) { - table->hash = kmalloc(UDP_HTABLE_SIZE_MIN * - 2 * sizeof(struct udp_hslot), GFP_KERNEL); - if (!table->hash) - panic(name); - table->log = ilog2(UDP_HTABLE_SIZE_MIN); - table->mask = UDP_HTABLE_SIZE_MIN - 1; - } + table->hash = alloc_large_system_hash(name, + 2 * sizeof(struct udp_hslot), + uhash_entries, + 21, /* one slot per 2 MB */ + 0, + &table->log, + &table->mask, + UDP_HTABLE_SIZE_MIN, + 64 * 1024); + table->hash2 = table->hash + (table->mask + 1); for (i = 0; i <= table->mask; i++) { INIT_HLIST_NULLS_HEAD(&table->hash[i].head, i);
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