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Subject: Re: INFO: task hung in filemap_fault
References: <001a11444d0e7bfd7f05609956c6@google.com>
 <82d89066-7dd2-12fe-3cc0-c8d624fe0d51@I-love.SAKURA.ne.jp>
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Message-ID: <b434ed3e-c066-9618-96ca-fd66a362a4fe@I-love.SAKURA.ne.jp>
Date: Tue, 19 Dec 2017 07:19:45 +0900
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To: syzbot <bot+980f5e5fc060c37505bd65abb49a963518b269d9@syzkaller.appspotmail.com>, ak@linux.intel.com, akpm@linux-foundation.org, jack@suse.cz, jlayton@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mgorman@techsingularity.net, mingo@kernel.org, npiggin@gmail.com, rgoldwyn@suse.com, syzkaller-bugs@googlegroups.com

On 2017/12/18 23:52, Tetsuo Handa wrote:
> On 2017/12/18 17:43, syzbot wrote:
>> Hello,
>>
>> syzkaller hit the following crash on 6084b576dca2e898f5c101baef151f7bfdbb606d
>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>>
>> Unfortunately, I don't have any reproducer for this bug yet.
>>
> 
> This log has a lot of mmap() but also has Android's binder messages.
> 
> r9 = syz_open_dev$binder(&(0x7f0000000000)='/dev/binder#\x00', 0x0, 0x800)
> 
> [   49.200735] binder: 9749:9755 IncRefs 0 refcount change on invalid ref 2 ret -22
> [   49.221514] binder: 9749:9755 Acquire 1 refcount change on invalid ref 4 ret -22
> [   49.233325] binder: 9749:9755 Acquire 1 refcount change on invalid ref 0 ret -22
> [   49.241979] binder: binder_mmap: 9749 205a3000-205a7000 bad vm_flags failed -1
> [   49.256949] binder: 9749:9755 unknown command 0
> [   49.262470] binder: 9749:9755 ioctl c0306201 20000fd0 returned -22
> [   49.293365] binder: 9749:9755 IncRefs 0 refcount change on invalid ref 2 ret -22
> [   49.301297] binder: binder_mmap: 9749 205a3000-205a7000 bad vm_flags failed -1
> [   49.314146] binder: 9749:9755 Acquire 1 refcount change on invalid ref 4 ret -22
> [   49.322732] binder: 9749:9755 Acquire 1 refcount change on invalid ref 0 ret -22
> [   49.332063] binder: 9749:9755 Release 1 refcount change on invalid ref 1 ret -22
> [   49.340796] binder: 9749:9755 Acquire 1 refcount change on invalid ref 2 ret -22
> [   49.349457] binder: 9749:9755 BC_DEAD_BINDER_DONE 0000000000000001 not found
> [   49.349462] binder: 9749:9755 BC_DEAD_BINDER_DONE 0000000000000000 not found
> 
> [  246.752088] INFO: task syz-executor7:10280 blocked for more than 120 seconds.
> 
> Anything that hung after uptime > 46.75 can be reported at uptime = 246.75, can't it?

Typo. I wanted to say 126.75 >= uptime > 6.75.
khungtaskd warning with 120 seconds check interval can be delayed for up to 240 seconds.

> 
> Is it possible to reproduce this problem by running the same program?

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