Messages in this thread | | | Subject | Re: [PATCH] kernel/hung_task.c: Monitor killed tasks. | From | Tetsuo Handa <> | Date | Wed, 22 May 2019 21:38:45 +0900 |
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Hello, Stephen.
I want to send debug printk() patches to linux-next.git. Petr Mladek is suggesting me to have a git tree for debug printk() patches. But it seems that there is "git quiltimport" command, and I prefer "subversion + quilt", and I don't have trees for sending "git pull" requests. Therefore, just ignoring "git quiltimport" failure is fine. What do you think?
On 2019/05/16 21:38, Tetsuo Handa wrote: > On 2019/05/16 20:57, Petr Mladek wrote: >> CCed Stephen to discuss linux-next related question at the bottom >> of the mail. >> >> On Thu 2019-05-16 17:19:12, Tetsuo Handa wrote: >>> On 2019/05/15 19:55, Petr Mladek wrote: >>> But in the context of syzbot's testing where there are only 2 CPUs >>> in the target VM (which means that only small number of threads and >>> not so much memory) and threads get SIGKILL after 5 seconds from fork(), >>> being unable to reach do_exit() within 10 seconds is likely a sign of >>> something went wrong. For example, 6 out of 7 trials of a reproducer for >>> https://syzkaller.appspot.com/bug?id=835a0b9e75b14b55112661cbc61ca8b8f0edf767 >>> resulted in "no output from test machine" rather than "task hung". >>> This patch is revealing that such killed threads are failing to reach >>> do_exit() because they are trapped at unkillable retry loop due to a >>> race bug. >>> >>> Therefore, I would like to try this patch in linux-next.git for feasibility >>> testing whether this patch helps finding more bugs and reproducers for such >>> bugs, by bringing "unable to terminate threads" reports out of "no output from >>> test machine" reports. We can add sysctl settings before sending to linux.git. >> >> In this case, the watchdog should get enabled on with >> CONFIG_DEBUG_AID_FOR_SYZBOT > > Since "[PATCH] printk: Monitor change of console loglevel." is one time (only > needed until we find the reason of silence), testing on only linux-next.git > is sufficient and it gets enabled on with CONFIG_DEBUG_AID_FOR_SYZBOT. > >> >> Also we should ask/inform Stephen about this. I am not sure >> if he is willing to resolve eventual conflicts for these >> syzboot-specific patches that are not upstream candidates. >> >> A solution might be to create sysbot-specific for-next branch >> that Stephen might simply ignore when there are conflicts. >> And you would be responsible for updating it. > > syzbot tests not only linux-next.git but also various trees, and tests > attempted depends on target git tree. Therefore, apart from whether we > can introduce a kernel config option for fuzzing testing, > "[PATCH] kernel/hung_task.c: Monitor killed tasks." is expected to be > in linux.git. This patch will eventually become upstream candidate. >
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