From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C350C48BE6 for ; Wed, 16 Jun 2021 09:17:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2709B61107 for ; Wed, 16 Jun 2021 09:17:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232371AbhFPJTM (ORCPT ); Wed, 16 Jun 2021 05:19:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232279AbhFPJTK (ORCPT ); Wed, 16 Jun 2021 05:19:10 -0400 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4579FC061574; Wed, 16 Jun 2021 02:17:04 -0700 (PDT) Received: by mail-ej1-x632.google.com with SMTP id hq2so2751459ejc.2; Wed, 16 Jun 2021 02:17:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LqKUd7jpWI45dwJktjSkPLrqSZglJAQGDy+xWdh0jXY=; b=VaTZhGozIGkXk1Fk0y6lm3uqIM9EpHbCZOsKTehQDM6cFZ10wcgvVXrXpoFZCdGCSV TAlGhae+WPmKjAJ+YMBg4uCBJkgnfubNNxrFmlgfrLDCYMxMEWwqRMpFaqzL3RH57NVa gHTq24s1oRuRMxSn/pwtAEzNIowqYwsRrkERtfIp4ri+Qk35Nge4rDGcRWFCuHAEYRw/ TMfRr3g3bMoPfLOVFowcYXZHRUwCbXYROl3X/1Ci1vPYccBRPa2enjDZxjSAnBvVYaKJ WbINiqVIIpIUeZEqYW1/9dV0NR6VoirJVClzxf9HQZuVKZN6KPPHbLwpk+14d+VVYTDt yrHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LqKUd7jpWI45dwJktjSkPLrqSZglJAQGDy+xWdh0jXY=; b=iAtLX6pMM+lZfZSq7DO7Gs1/6nLQoz+meWCntTMBoieaL8ETsz0ZZuKHL1kkFLtUkM T5XFBrv5EBS1hiDKUqPTxDFZsZpY/cQM/396NfRo0wcEO2JQgrviZRDWrclg5Lcrade2 6XX+l61IA+dAdVQDsRNukCk6bh6JAdEN8c5xQls9Enl6UeM4EiAisF76sVkSzymb+/43 166T/iXaRZVEgDR0nOYctaGClCcSHR6vbs6ny++caT5CWkAOayOjE9e351JKn8huydiC 1Ifc2kbHoguzGDVBWPH9C9X0YKolC//d/m3nJF7XqZeWaGgs+xPxS+RmBt8+UDhJgpH0 /Jkw== X-Gm-Message-State: AOAM532aZOVIpdUai6axUfp9JT55NY1/MSy84oJ0PxAtdMtC0GsC9wJc Fs6LJwGTxAevxGBZkMBI3b+6402xCyB8DHZ3ZT8= X-Google-Smtp-Source: ABdhPJybOgsSRMZfoEFaLEQxyeTtpNPDMN0fthWKyW6dAjnJmPwYFo1Zwf/q4os4LkGIYg6EhzdwsZuL8iZ047roZLY= X-Received: by 2002:a17:906:994d:: with SMTP id zm13mr4149388ejb.427.1623835022871; Wed, 16 Jun 2021 02:17:02 -0700 (PDT) MIME-Version: 1.0 References: <20210512144743.039977287@linuxfoundation.org> <20210512144748.600206118@linuxfoundation.org> In-Reply-To: From: Amit Klein Date: Wed, 16 Jun 2021 12:16:52 +0300 Message-ID: Subject: Re: [PATCH 5.4 175/244] inet: use bigger hash table for IP ID generation To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Eric Dumazet , Willy Tarreau , "David S. Miller" , Sasha Levin Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 #include #include +#include #include #include #include @@ -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 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