Here is the patch (minus headers, description, etc. - I believe these can be copied as is from the 5.x patch, but not sure about the rules...). It can be applied to 4.14.236. If this is OK, I can move on to 4.9 and 4.4.
net/ipv4/route.c | 41 ++++++++++++++++++++++++++++------------- 1 file changed, 28 insertions(+), 13 deletions(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 78d6bc61a1d8..022a2b748da3 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -70,6 +70,7 @@ #include <linux/types.h> #include <linux/kernel.h> #include <linux/mm.h> +#include <linux/memblock.h> #include <linux/string.h> #include <linux/socket.h> #include <linux/sockios.h> @@ -485,8 +486,10 @@ static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr) __ipv4_confirm_neigh(dev, *(__force u32 *)pkey); }
-#define IP_IDENTS_SZ 2048u - +/* Hash tables of size 2048..262144 depending on RAM size. + * Each bucket uses 8 bytes. + */ +static u32 ip_idents_mask __read_mostly; static atomic_t *ip_idents __read_mostly; static u32 *ip_tstamps __read_mostly;
@@ -496,12 +499,16 @@ static u32 *ip_tstamps __read_mostly; */ u32 ip_idents_reserve(u32 hash, int segs) { - u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ; - atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ; - u32 old = ACCESS_ONCE(*p_tstamp); - u32 now = (u32)jiffies; + u32 bucket, old, now = (u32)jiffies; + atomic_t *p_id; + u32 *p_tstamp; u32 delta = 0;
+ bucket = hash & ip_idents_mask; + p_tstamp = ip_tstamps + bucket; + p_id = ip_idents + bucket; + old = READ_ONCE(*p_tstamp); + if (old != now && cmpxchg(p_tstamp, old, now) == old) delta = prandom_u32_max(now - old);
@@ -3099,17 +3106,25 @@ struct ip_rt_acct __percpu *ip_rt_acct __read_mostly; int __init ip_rt_init(void) { int rc = 0; + void *idents_hash; int cpu;
- ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL); - if (!ip_idents) - panic("IP: failed to allocate ip_idents\n"); + /* For modern hosts, this will use 2 MB of memory */ + idents_hash = alloc_large_system_hash("IP idents", + sizeof(*ip_idents) + sizeof(*ip_tstamps), + 0, + 16, /* one bucket per 64 KB */ + HASH_ZERO, + NULL, + &ip_idents_mask, + 2048, + 256*1024); + + ip_idents = idents_hash;
- prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents)); + prandom_bytes(ip_idents, (ip_idents_mask + 1) * sizeof(*ip_idents));
- ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL); - if (!ip_tstamps) - panic("IP: failed to allocate ip_tstamps\n"); + ip_tstamps = idents_hash + (ip_idents_mask + 1) * sizeof(*ip_idents);
for_each_possible_cpu(cpu) { struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
On Wed, Jun 16, 2021 at 10:16 AM Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:
On Wed, Jun 16, 2021 at 10:02:44AM +0300, Amit Klein wrote:
Hi Greg et al.
I see that you backported this patch (increasing the IP ID hash table size) to the newer LTS branches more than a month ago. But I don't see that it was backported to older LTS branches (4.19, 4.14, 4.9, 4.4). Is this intentional?
It applies cleanly to 4.19, but not the older ones. If you think it is needed there for those kernels, please provide a working backport that we can apply.
thanks,
greg k-h