Greetings, 0day kernel testing robot got the below dmesg and the first bad commit is git://internal_merge_and_test_tree devel-catchup-201604051137 commit 3b24d854cb35383c30642116e5992fd619bdc9bc Author: Eric Dumazet <edumazet(a)google.com&gt; AuthorDate: Fri Apr 1 08:52:17 2016 -0700 Commit: David S. Miller <davem(a)davemloft.net&gt; CommitDate: Mon Apr 4 22:11:20 2016 -0400 tcp/dccp: do not touch listener sk_refcnt under synflood When a SYNFLOOD targets a non SO_REUSEPORT listener, multiple cpus contend on sk->sk_refcnt and sk->sk_wmem_alloc changes. By letting listeners use SOCK_RCU_FREE infrastructure, we can relax TCP_LISTEN lookup rules and avoid touching sk_refcnt Note that we still use SLAB_DESTROY_BY_RCU rules for other sockets, only listeners are impacted by this change. Peak performance under SYNFLOOD is increased by ~33% : On my test machine, I could process 3.2 Mpps instead of 2.4 Mpps Most consuming functions are now skb_set_owner_w() and sock_wfree() contending on sk->sk_wmem_alloc when cooking SYNACK and freeing them. Signed-off-by: Eric Dumazet <edumazet(a)google.com&gt; Signed-off-by: David S. Miller <davem(a)davemloft.net&gt; +---------------------------------------------------------------+------------+------------+------------+ | | 3a5d1c0e7c | 3b24d854cb | 366ff22c70 | +---------------------------------------------------------------+------------+------------+------------+ | boot_successes | 468 | 120 | 10 | | boot_failures | 0 | 40 | 13 | | BUG:unable_to_handle_kernel | 0 | 17 | 2 | | Oops | 0 | 39 | 5 | | RIP:__inet_hash | 0 | 39 | 5 | | Kernel_panic-not_syncing:Fatal_exception_in_interrupt | 0 | 40 | 5 | | backtrace:inet_listen | 0 | 40 | 5 | | backtrace:SyS_listen | 0 | 40 | 5 | | BUG:unable_to_handle#kernel | 0 | 1 | | | BUG:unable_to_handl12e_kernel_paging_requestpaging_request_at | 0 | 1 | | | BUG:unabl[main]Setsockopt(###b000#)on_fd#[#:#:#] | 0 | 1 | | | BUG | 0 | 1 | | | IP-Config:Auto-configuration_of_network_failed | 0 | 0 | 8 | +---------------------------------------------------------------+------------+------------+------------+ [main] Setsockopt(1 c 68b000 4) on fd 32 [26:1:45] [main] Setsockopt(116 7f 68b000 4) on fd 34 [37:5:5] [main] Setsockopt(1 23 68b000 7d) on fd 35 [1:1:1] [ 41.825518] BUG: unabl[main] Setsockopt(0 1 68b000 4) on fd 36 [2:1:0] [main] Setsockopt(0 d 68b000 4) on fd 38 [10:2:0] [main] Setsockopt(1 21 68b000 4) on fd 40 [16:3:16] [main] Setsockopt(116 7f 68b000 4) on fd 43 [37:5:2] git bisect start 366ff22c7048d89447e3b5e86fb804a99f823dfc 9735a22799b9214d17d3c231fe377fc852f042e9 -- git bisect bad b2457dab739a92d7d648872fc0954d2a34525fa2 # 13:53 6- 8 Merge 'tj-libata/for-next' into devel-spot-201604051227 git bisect bad d6c4bd205e250640f8a60867448c6123534ad732 # 14:06 1- 3 Merge 'net/master' into devel-spot-201604051227 git bisect bad 545f577347719983aa86e69bdd634db371e79050 # 14:16 5- 2 Merge 'linux-review/Masahiro-Yamada/clk-let-clk_disable-return-immediately-if-clk-is-NULL-or-error/20160405-100803' into devel-spot-201604051227 git bisect bad ded86f7058b0066db52dfd9aaf37902f3c7a3ca3 # 14:43 5- 5 Merge 'linux-review/David-Kershner/staging-unisys-clean-gotos-in-visorchipset/20160405-113613' into devel-spot-201604051227 git bisect bad 294ae461218046500e36c9ca8239b60df24f6dc2 # 15:08 4- 3 Merge 'linux-review/Shuah-Khan/selftests-media_device_test-fix-to-close-the-fd-before-exit/20160405-114430' into devel-spot-201604051227 git bisect good e72de1121f51267def9ba4b6317367ad5b0ee8c2 # 15:41 110+ 2 Merge 'linux-review/Vignesh-R/spi-Add-DMA-support-for-spi_flash_read/20160405-115307' into devel-spot-201604051227 git bisect bad d479077b6b5cae6ba1dfaeffbc673b2d03ed4908 # 15:55 1- 1 Merge 'bpf/master' into devel-spot-201604051227 git bisect good f74df0be82d7d29747bfd68d955f4f573f9e5691 # 16:23 111+ 0 net: dsa: mv88e6xxx: variable number of databases git bisect good 43e2dfb23eb8f3698718ec1e3936c76912de1c30 # 16:58 118+ 0 Merge branch '10GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue git bisect bad 9caad864151e525929d323de96cad382da49c3b2 # 17:06 13- 7 tcp: increment sk_drops for listeners git bisect good 2d331915a04144dad738e725769d8fac06ef6155 # 17:38 150+ 0 tcp/dccp: use rcu locking in inet_diag_find_one_icsk() git bisect bad 3b24d854cb35383c30642116e5992fd619bdc9bc # 17:44 1- 2 tcp/dccp: do not touch listener sk_refcnt under synflood git bisect good 3a5d1c0e7cb5ba91aabbd7e28626e3cc925f8093 # 18:46 151+ 0 inet: reqsk_alloc() needs to take care of dead listeners # first bad commit: [3b24d854cb35383c30642116e5992fd619bdc9bc] tcp/dccp: do not touch listener sk_refcnt under synflood git bisect good 3a5d1c0e7cb5ba91aabbd7e28626e3cc925f8093 # 18:54 468+ 0 inet: reqsk_alloc() needs to take care of dead listeners # extra tests with DEBUG_INFO git bisect bad 3b24d854cb35383c30642116e5992fd619bdc9bc # 19:04 10- 13 tcp/dccp: do not touch listener sk_refcnt under synflood # extra tests on HEAD of linux-devel/devel-spot-201604051227 git bisect bad 366ff22c7048d89447e3b5e86fb804a99f823dfc # 19:04 0- 13 0day head guard for 'devel-spot-201604051227' # extra tests on tree/branch linux-devel/devel-catchup-201604051137 git bisect bad e9fbc2f3aac59f628d7fb2b8358b65fcf997a7a6 # 22:31 6- 7 0day head guard for 'devel-catchup-201604051137' # extra tests on tree/branch linus/master git bisect good 1e1e5ce78ff0fb2b1b9296894883c82de29057d0 # 22:44 455+ 8 Merge tag 'linux-kselftest-4.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest # extra tests on tree/branch linux-next/master git bisect good aa36efa8b2a4ff33c70ef532ec58d49148f1872a # 22:58 458+ 4 Add linux-next specific files for 20160405 This script may reproduce the error. ---------------------------------------------------------------------------- #!/bin/bash kernel=$1 initrd=quantal-core-x86_64.cgz wget --no-clobber https://github.com/fengguang/reproduce-kernel-bug/raw/master/initrd/$initrd kvm=( qemu-system-x86_64 -enable-kvm -cpu kvm64 -kernel $kernel -initrd $initrd -m 300 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -serial stdio -display none -monitor null ) append=( hung_task_panic=1 earlyprintk=ttyS0,115200 systemd.log_level=err debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal root=/dev/ram0 rw drbd.minor_count=8 ) "${kvm[@]}" --append "${append[*]}" ---------------------------------------------------------------------------- --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/lkp Intel Corporation