linux-kernel - Re: linux-next test error

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Date:   Wed, 5 Sep 2018 11:57:55 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Souptick Joarder <jrdr.linux@...il.com>
Cc:     Jan Kara <jack@...e.cz>,
        syzbot <syzbot+87a05ae4accd500f5242@...kaller.appspotmail.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        tim.c.chen@...ux.intel.com, zwisler@...nel.org
Subject: Re: linux-next test error

On Wed, Sep 5, 2018 at 11:53 AM, Dmitry Vyukov <dvyukov@...gle.com> wrote:
> On Wed, Sep 5, 2018 at 11:50 AM, Souptick Joarder <jrdr.linux@...il.com> wrote:
>> On Wed, Sep 5, 2018 at 2:25 PM Jan Kara <jack@...e.cz> wrote:
>>>
>>> On Wed 05-09-18 00:13:02, syzbot wrote:
>>> > Hello,
>>> >
>>> > syzbot found the following crash on:
>>> >
>>> > HEAD commit:    387ac6229ecf Add linux-next specific files for 20180905
>>> > git tree:       linux-next
>>> > console output: https://syzkaller.appspot.com/x/log.txt?x=149c67a6400000
>>> > kernel config:  https://syzkaller.appspot.com/x/.config?x=ad5163873ecfbc32
>>> > dashboard link: https://syzkaller.appspot.com/bug?extid=87a05ae4accd500f5242
>>> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>> >
>>> > Unfortunately, I don't have any reproducer for this crash yet.
>>> >
>>> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>> > Reported-by: syzbot+87a05ae4accd500f5242@...kaller.appspotmail.com
>>> >
>>> > INFO: task hung in do_page_mkwriteINFO: task syz-fuzzer:4876 blocked for
>>> > more than 140 seconds.
>>> >       Not tainted 4.19.0-rc2-next-20180905+ #56
>>> > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>> > syz-fuzzer      D21704  4876   4871 0x00000000
>>> > Call Trace:
>>> >  context_switch kernel/sched/core.c:2825 [inline]
>>> >  __schedule+0x87c/0x1df0 kernel/sched/core.c:3473
>>> >  schedule+0xfb/0x450 kernel/sched/core.c:3517
>>> >  io_schedule+0x1c/0x70 kernel/sched/core.c:5140
>>> >  wait_on_page_bit_common mm/filemap.c:1100 [inline]
>>> >  __lock_page+0x5b7/0x7a0 mm/filemap.c:1273
>>> >  lock_page include/linux/pagemap.h:483 [inline]
>>> >  do_page_mkwrite+0x429/0x520 mm/memory.c:2391
>>>
>>> Waiting for page lock after ->page_mkwrite callback. Which means
>>> ->page_mkwrite did not return VM_FAULT_LOCKED but 0. Looking into
>>> linux-next... indeed "fs: convert return type int to vm_fault_t" has busted
>>> block_page_mkwrite(). It has to return VM_FAULT_LOCKED and not 0 now.
>>> Souptick, can I ask you to run 'fstests' for at least common filesystems
>>> like ext4, xfs, btrfs when you change generic filesystem code please? That
>>> would catch a bug like this immediately. Thanks.
>>>
>>
>> "fs: convert return type int to vm_fault_t" is still under
>> review/discusson and not yet merge
>> into linux-next. I am not seeing it into linux-next tree.Can you
>> please share the commit id ?
>
> syzbot gave commit id in the report (see above)

-mawilcox@...rosoft.com as I getting bounces from mail server