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Subject: Re: [PATCH 1/2] uio: change to use the mutex lock instead of the spin
 lock
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, pkalever@redhat.com,
        pkarampu@redhat.com, atumball@redhat.com, sabose@redhat.com,
        mchristi@redhat.com
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 <20180705163338.GA14941@kroah.com>
From:   Xiubo Li <xiubli@redhat.com>
Message-ID: <24daa19c-eb1b-014e-c00f-8c8c3da0d935@redhat.com>
Date:   Fri, 6 Jul 2018 07:21:02 +0800
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On 2018/7/6 0:33, Greg KH wrote:
> On Thu, Jul 05, 2018 at 12:27:27PM -0400, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> We are hitting a regression with the following commit:
>>
>> commit a93e7b331568227500186a465fee3c2cb5dffd1f
>> Author: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
>> Date:   Mon May 14 13:32:23 2018 +1200
>>
>>      uio: Prevent device destruction while fds are open
>>
>> The problem is the addition of spin_lock_irqsave in uio_write. This
>> leads to hitting  uio_write -> copy_from_user -> _copy_from_user ->
>> might_fault and the logs filling up with sleeping warnings.
>>
>> I also noticed some uio drivers allocate memory, sleep, grab mutexes
>> from callouts like open() and release and uio is now doing
>> spin_lock_irqsave while calling them.
>>
>> Reported-by: Mike Christie <mchristi@redhat.com>
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>>   drivers/uio/uio.c          | 33 ++++++++++++++-------------------
>>   include/linux/uio_driver.h |  2 +-
>>   2 files changed, 15 insertions(+), 20 deletions(-)
> Any specific reason you did not also cc: the author of the above patch
> to review this one?
Ah, no, sorry for that, I just used the following script to get the 
mantainer and the list, and here was to late at night and I was a little 
dizzy forgetting that:

[root@gblock2 scsi]# ./scripts/get_maintainer.pl drivers/uio/
Greg Kroah-Hartman <gregkh@linuxfoundation.org> (maintainer:USERSPACE 
I/O (UIO))
linux-kernel@vger.kernel.org (open list)
[root@gblock2 scsi]#


And all the others are my team member, because this is a high priority 
bug fix, so I cced them to let them know the status of this patch set.

I will resend it right now.

Thanks very much for you reminding of this.

BRs
Xiubo


> Please fix up and resend.
>
> greg k-h