Hello, Alexei and Daniel. Can you show us how to run testcases you are testing?
On 2018/09/22 22:25, Tetsuo Handa wrote: > Hello. > > syzbot is reporting many lockup problems on bpf.git / bpf-next.git / net.git > / net-next.git trees. > > INFO: rcu detected stall in br_multicast_port_group_expired (2) > > https://syzkaller.appspot.com/bug?id=15c7ad8cf35a07059e8a697a22527e11d294bc94 > > INFO: rcu detected stall in tun_chr_close > > https://syzkaller.appspot.com/bug?id=6c50618bde03e5a2eefdd0269cf9739c5ebb8270 > > INFO: rcu detected stall in discover_timer > > https://syzkaller.appspot.com/bug?id=55da031ddb910e58ab9c6853a5784efd94f03b54 > > INFO: rcu detected stall in ret_from_fork (2) > > https://syzkaller.appspot.com/bug?id=c83129a6683b44b39f5b8864a1325893c9218363 > > INFO: rcu detected stall in addrconf_rs_timer > > https://syzkaller.appspot.com/bug?id=21c029af65f81488edbc07a10ed20792444711b6 > > INFO: rcu detected stall in kthread (2) > > https://syzkaller.appspot.com/bug?id=6accd1ed11c31110fed1982f6ad38cc9676477d2 > > INFO: rcu detected stall in ext4_filemap_fault > > https://syzkaller.appspot.com/bug?id=817e38d20e9ee53390ac361bf0fd2007eaf188af > > INFO: rcu detected stall in run_timer_softirq (2) > > https://syzkaller.appspot.com/bug?id=f5a230a3ff7822f8d39fddf8485931bd06ae47fe > > INFO: rcu detected stall in bpf_prog_ADDR > > https://syzkaller.appspot.com/bug?id=fb4911fd0e861171cc55124e209f810a0dd68744 > > INFO: rcu detected stall in __run_timers (2) > > https://syzkaller.appspot.com/bug?id=65416569ddc8d2feb8f19066aa761f5a47f7451a > > The cause of lockup seems to be flood of printk() messages from memory > allocation > failures, and one of out_of_memory() messages indicates that skbuff_head_cache > usage is huge enough to suspect in-kernel memory leaks. > > [ 1554.547011] skbuff_head_cache 1847887KB 1847887KB > > Unfortunately, we cannot find from logs what syzbot is trying to do > because constant printk() messages is flooding away syzkaller messages. > Can you try running your testcases with kmemleak enabled? > On 2018/09/27 2:35, Dmitry Vyukov wrote: > I also started suspecting Apparmor. We switched to Apparmor on Aug 30: > https://groups.google.com/d/msg/syzkaller-bugs/o73lO4KGh0w/j9pcH2tSBAAJ > Now the instances that use SELinux and Smack explicitly contain that > in the name, but the rest are Apparmor. > Aug 30 roughly matches these assorted "task hung" reports. Perhaps > some Apparmor hook leaks a reference to skbs? Maybe. They have CONFIG_DEFAULT_SECURITY="apparmor". But I'm wondering why this problem is not occurring on linux-next.git when this problem is occurring on bpf.git / bpf-next.git / net.git / net-next.git trees. Is syzbot running different testcases depending on which git tree is targeted?
