| Message ID | 20241101104922.68956-1-deliran@verdict.gg (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v5] net: ipv4: Cache pmtu for all packet paths if multipath enabled | expand |
On Fri, 1 Nov 2024 10:48:57 +0000 Vladimir Vdovin wrote:
> + pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 0"
This new test seems to fail in our CI:
# TEST: ipv4: PMTU multipath nh exceptions [FAIL]
# there are not enough cached exceptions
https://netdev-3.bots.linux.dev/vmksft-net/results/840861/3-pmtu-sh/stdout
Also some process notes:
- please don't post multiple versions of the patch a day:
https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#tl-dr
- please avoid posting new versions in-reply-to the old one
On Fri Nov 1, 2024 at 4:45 PM MSK, Jakub Kicinski wrote: > On Fri, 1 Nov 2024 10:48:57 +0000 Vladimir Vdovin wrote: > > + pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 0" > > This new test seems to fail in our CI: > > # TEST: ipv4: PMTU multipath nh exceptions [FAIL] > # there are not enough cached exceptions > > https://netdev-3.bots.linux.dev/vmksft-net/results/840861/3-pmtu-sh/stdout Yes it failed in V4 patch, in this V5 its already ok: # TEST: ipv4: PMTU multipath nh exceptions [ OK ] ok 1 selftests: net: pmtu.sh https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/841042/2-pmtu-sh/stdout But in V5, there is failed test, not sure that this patch causes fail: https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/841042/31-busy-poll-test-sh/stdout > > Also some process notes: > - please don't post multiple versions of the patch a day: > https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#tl-dr > - please avoid posting new versions in-reply-to the old one Thanks, will keep it in mind next time, sorry for my ignorance
Hi, On 11/1/24 18:34, Vladimir Vdovin wrote: > On Fri Nov 1, 2024 at 4:45 PM MSK, Jakub Kicinski wrote: >> On Fri, 1 Nov 2024 10:48:57 +0000 Vladimir Vdovin wrote: >>> + pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 0" >> >> This new test seems to fail in our CI: >> >> # TEST: ipv4: PMTU multipath nh exceptions [FAIL] >> # there are not enough cached exceptions >> >> https://netdev-3.bots.linux.dev/vmksft-net/results/840861/3-pmtu-sh/stdout > > Yes it failed in V4 patch, in this V5 its already ok: > > # TEST: ipv4: PMTU multipath nh exceptions [ OK ] > ok 1 selftests: net: pmtu.sh > > https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/841042/2-pmtu-sh/stdout > > But in V5, there is failed test, not sure that this patch causes fail: > https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/841042/31-busy-poll-test-sh/stdout > >> >> Also some process notes: >> - please don't post multiple versions of the patch a day: >> https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#tl-dr >> - please avoid posting new versions in-reply-to the old one > Thanks, will keep it in mind next time, sorry for my ignorance Some additional notes: - please do answer to Ido's question: what about ipv6? - move the changelog after the SoB tag and a '---' separator, so that it will not be included into the git commit message - post new revisions of the patch in a different thread Thanks, Paolo
On Sat Nov 2, 2024 at 11:49 AM MSK, Paolo Abeni wrote: > Hi, > > On 11/1/24 18:34, Vladimir Vdovin wrote: > > On Fri Nov 1, 2024 at 4:45 PM MSK, Jakub Kicinski wrote: > >> On Fri, 1 Nov 2024 10:48:57 +0000 Vladimir Vdovin wrote: > >>> + pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 0" > >> > >> This new test seems to fail in our CI: > >> > >> # TEST: ipv4: PMTU multipath nh exceptions [FAIL] > >> # there are not enough cached exceptions > >> > >> https://netdev-3.bots.linux.dev/vmksft-net/results/840861/3-pmtu-sh/stdout > > > > Yes it failed in V4 patch, in this V5 its already ok: > > > > # TEST: ipv4: PMTU multipath nh exceptions [ OK ] > > ok 1 selftests: net: pmtu.sh > > > > https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/841042/2-pmtu-sh/stdout > > > > But in V5, there is failed test, not sure that this patch causes fail: > > https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/841042/31-busy-poll-test-sh/stdout > > > >> > >> Also some process notes: > >> - please don't post multiple versions of the patch a day: > >> https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#tl-dr > >> - please avoid posting new versions in-reply-to the old one > > Thanks, will keep it in mind next time, sorry for my ignorance > > Some additional notes: > > - please do answer to Ido's question: what about ipv6? > - move the changelog after the SoB tag and a '---' separator, so that it > will not be included into the git commit message > - post new revisions of the patch in a different thread > > Thanks, > > Paolo Thanks for your comments, I will resend patch with fixed commit message as new thread.
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 723ac9181558..41162b5cc4cb 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1027,6 +1027,19 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) struct fib_nh_common *nhc; fib_select_path(net, &res, fl4, NULL); +#ifdef CONFIG_IP_ROUTE_MULTIPATH + if (fib_info_num_path(res.fi) > 1) { + int nhsel; + + for (nhsel = 0; nhsel < fib_info_num_path(res.fi); nhsel++) { + nhc = fib_info_nhc(res.fi, nhsel); + update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock, + jiffies + net->ipv4.ip_rt_mtu_expires); + } + rcu_read_unlock(); + return; + } +#endif /* CONFIG_IP_ROUTE_MULTIPATH */ nhc = FIB_RES_NHC(res); update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock, jiffies + net->ipv4.ip_rt_mtu_expires); diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh index 569bce8b6383..a0159340fe84 100755 --- a/tools/testing/selftests/net/pmtu.sh +++ b/tools/testing/selftests/net/pmtu.sh @@ -266,7 +266,8 @@ tests=" list_flush_ipv4_exception ipv4: list and flush cached exceptions 1 list_flush_ipv6_exception ipv6: list and flush cached exceptions 1 pmtu_ipv4_route_change ipv4: PMTU exception w/route replace 1 - pmtu_ipv6_route_change ipv6: PMTU exception w/route replace 1" + pmtu_ipv6_route_change ipv6: PMTU exception w/route replace 1 + pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 0" # Addressing and routing for tests with routers: four network segments, with # index SEGMENT between 1 and 4, a common prefix (PREFIX4 or PREFIX6) and an @@ -2329,6 +2330,81 @@ test_pmtu_ipv6_route_change() { test_pmtu_ipvX_route_change 6 } +test_pmtu_ipv4_mp_exceptions() { + setup namespaces routing || return $ksft_skip + + ip nexthop ls >/dev/null 2>&1 + if [ $? -ne 0 ]; then + echo "Nexthop objects not supported; skipping tests" + exit $ksft_skip + fi + + trace "${ns_a}" veth_A-R1 "${ns_r1}" veth_R1-A \ + "${ns_r1}" veth_R1-B "${ns_b}" veth_B-R1 \ + "${ns_a}" veth_A-R2 "${ns_r2}" veth_R2-A \ + "${ns_r2}" veth_R2-B "${ns_b}" veth_B-R2 + + dummy0_a="192.168.99.99" + dummy0_b="192.168.88.88" + + # Set up initial MTU values + mtu "${ns_a}" veth_A-R1 2000 + mtu "${ns_r1}" veth_R1-A 2000 + mtu "${ns_r1}" veth_R1-B 1500 + mtu "${ns_b}" veth_B-R1 1500 + + mtu "${ns_a}" veth_A-R2 2000 + mtu "${ns_r2}" veth_R2-A 2000 + mtu "${ns_r2}" veth_R2-B 1500 + mtu "${ns_b}" veth_B-R2 1500 + + fail=0 + + #Set up host A with multipath routes to host B dummy0_b + run_cmd ${ns_a} sysctl -q net.ipv4.fib_multipath_hash_policy=1 + run_cmd ${ns_a} sysctl -q net.ipv4.ip_forward=1 + run_cmd ${ns_a} ip link add dummy0 mtu 2000 type dummy + run_cmd ${ns_a} ip link set dummy0 up + run_cmd ${ns_a} ip addr add ${dummy0_a} dev dummy0 + run_cmd ${ns_a} ip nexthop add id 201 via ${prefix4}.${a_r1}.2 dev veth_A-R1 + run_cmd ${ns_a} ip nexthop add id 202 via ${prefix4}.${a_r2}.2 dev veth_A-R2 + run_cmd ${ns_a} ip nexthop add id 203 group 201/202 + run_cmd ${ns_a} ip route add ${dummy0_b} nhid 203 + + #Set up host B with multipath routes to host A dummy0_a + run_cmd ${ns_b} sysctl -q net.ipv4.fib_multipath_hash_policy=1 + run_cmd ${ns_b} sysctl -q net.ipv4.ip_forward=1 + run_cmd ${ns_b} ip link add dummy0 mtu 2000 type dummy + run_cmd ${ns_b} ip link set dummy0 up + run_cmd ${ns_b} ip addr add ${dummy0_b} dev dummy0 + run_cmd ${ns_b} ip nexthop add id 201 via ${prefix4}.${b_r1}.2 dev veth_A-R1 + run_cmd ${ns_b} ip nexthop add id 202 via ${prefix4}.${b_r2}.2 dev veth_A-R2 + run_cmd ${ns_b} ip nexthop add id 203 group 201/202 + run_cmd ${ns_b} ip route add ${dummy0_a} nhid 203 + + #Set up routers with routes to dummies + run_cmd ${ns_r1} ip route add ${dummy0_a} via ${prefix4}.${a_r1}.1 + run_cmd ${ns_r2} ip route add ${dummy0_a} via ${prefix4}.${a_r2}.1 + run_cmd ${ns_r1} ip route add ${dummy0_b} via ${prefix4}.${b_r1}.1 + run_cmd ${ns_r2} ip route add ${dummy0_b} via ${prefix4}.${b_r2}.1 + + + #Ping and expect two nexthop exceptions for two routes in nh group + run_cmd ${ns_a} ping -q -M want -i 0.1 -c 2 -s 1800 "${dummy0_b}" + + #Do route lookup before checking cached exceptions + run_cmd ${ns_a} ip route get ${dummy0_b} oif veth_A-R1 + run_cmd ${ns_a} ip route get ${dummy0_b} oif veth_A-R2 + + #Check cached exceptions + if [ "$(${ns_a} ip -oneline route list cache| grep mtu | wc -l)" -ne 2 ]; then + err " there are not enough cached exceptions" + fail=1 + fi + + return ${fail} +} + usage() { echo echo "$0 [OPTIONS] [TEST]..."
Check number of paths by fib_info_num_path(), and update_or_create_fnhe() for every path. Problem is that pmtu is cached only for the oif that has received icmp message "need to frag", other oifs will still try to use "default" iface mtu. V5: - make self test cleaner V4: - fix selftest, do route lookup before checking cached exceptions V3: - added selftest - fixed compile error V2: - fix fib_info_num_path parameter pass An example topology showing the problem: | host1 +---------+ | dummy0 | 10.179.20.18/32 mtu9000 +---------+ +-----------+----------------+ +---------+ +---------+ | ens17f0 | 10.179.2.141/31 | ens17f1 | 10.179.2.13/31 +---------+ +---------+ | (all here have mtu 9000) | +------+ +------+ | ro1 | 10.179.2.140/31 | ro2 | 10.179.2.12/31 +------+ +------+ | | ---------+------------+-------------------+------ | +-----+ | ro3 | 10.10.10.10 mtu1500 +-----+ | ======================================== some networks ======================================== | +-----+ | eth0| 10.10.30.30 mtu9000 +-----+ | host2 host1 have enabled multipath and sysctl net.ipv4.fib_multipath_hash_policy = 1: default proto static src 10.179.20.18 nexthop via 10.179.2.12 dev ens17f1 weight 1 nexthop via 10.179.2.140 dev ens17f0 weight 1 When host1 tries to do pmtud from 10.179.20.18/32 to host2, host1 receives at ens17f1 iface an icmp packet from ro3 that ro3 mtu=1500. And host1 caches it in nexthop exceptions cache. Problem is that it is cached only for the iface that has received icmp, and there is no way that ro3 will send icmp msg to host1 via another path. Host1 now have this routes to host2: ip r g 10.10.30.30 sport 30000 dport 443 10.10.30.30 via 10.179.2.12 dev ens17f1 src 10.179.20.18 uid 0 cache expires 521sec mtu 1500 ip r g 10.10.30.30 sport 30033 dport 443 10.10.30.30 via 10.179.2.140 dev ens17f0 src 10.179.20.18 uid 0 cache So when host1 tries again to reach host2 with mtu>1500, if packet flow is lucky enough to be hashed with oif=ens17f1 its ok, if oif=ens17f0 it blackholes and still gets icmp msgs from ro3 to ens17f1, until lucky day when ro3 will send it through another flow to ens17f0. Signed-off-by: Vladimir Vdovin <deliran@verdict.gg> --- net/ipv4/route.c | 13 +++++ tools/testing/selftests/net/pmtu.sh | 78 ++++++++++++++++++++++++++++- 2 files changed, 90 insertions(+), 1 deletion(-) base-commit: 66600fac7a984dea4ae095411f644770b2561ede