[dm-devel] dm-mq and end_clone_request()

[Bart Van Assche]

On 08/08/16 08:26, Laurence Oberman wrote:
>
>
> ----- Original Message -----
>> From: "Bart Van Assche" <Bart.VanAssche at sandisk.com>
>> To: "Laurence Oberman" <loberman at redhat.com>
>> Cc: dm-devel at redhat.com, linux-scsi at vger.kernel.org, "Mike Snitzer" <snitzer at redhat.com>, "Johannes Thumshirn"
>> <jthumshirn at suse.de>
>> Sent: Monday, August 8, 2016 11:11:56 AM
>> Subject: Re: [dm-devel] dm-mq and end_clone_request()
>>
>> On 08/06/16 07:47, Laurence Oberman wrote:
>>> [66814.772851]  [<ffffffff8118e72f>] ? panic+0x1eb/0x233
>>> [66814.800207]  [<ffffffff810308f8>] oops_end+0xb8/0xd0
>>> [66814.827454]  [<ffffffff8106977e>] no_context+0x13e/0x3a0
>>> [66814.858368]  [<ffffffff811f3feb>] ? __slab_free+0x9b/0x280
>>> [66814.890365]  [<ffffffff81069ace>] __bad_area_nosemaphore+0xee/0x1d0
>>> [66814.926508]  [<ffffffff81069bc4>] bad_area_nosemaphore+0x14/0x20
>>> [66814.959939]  [<ffffffff8106a269>] __do_page_fault+0x89/0x4a0
>>> [66814.992039]  [<ffffffff811f3feb>] ? __slab_free+0x9b/0x280
>>> [66815.023052]  [<ffffffff8106a6b0>] do_page_fault+0x30/0x80
>>> [66815.053368]  [<ffffffff816c8b88>] page_fault+0x28/0x30
>>> [66815.083196]  [<ffffffff814ae4e9>] ? __scsi_remove_device+0x79/0x160
>>> [66815.117444]  [<ffffffff814ae5c2>] ? __scsi_remove_device+0x152/0x160
>>> [66815.152051]  [<ffffffff814ac790>] scsi_forget_host+0x60/0x70
>>> [66815.183939]  [<ffffffff814a0137>] scsi_remove_host+0x77/0x110
>>> [66815.216152]  [<ffffffffa0677be0>] srp_remove_work+0x90/0x200 [ib_srp]
>>> [66815.253221]  [<ffffffff810a2e72>] process_one_work+0x152/0x400
>>> [66815.286221]  [<ffffffff810a3765>] worker_thread+0x125/0x4b0
>>> [66815.317313]  [<ffffffff810a3640>] ? rescuer_thread+0x380/0x380
>>> [66815.349770]  [<ffffffff810a9298>] kthread+0xd8/0xf0
>>> [66815.376082]  [<ffffffff816c6b3f>] ret_from_fork+0x1f/0x40
>>> [66815.404767]  [<ffffffff810a91c0>] ? kthread_park+0x60/0x60
>>
>> Hello Laurence and Johannes,
>>
>> Later today I will start testing the following patch:
>>
>>
>> Subject: [PATCH] Fix a use-after-free in scsi_forget_host()
>>
>> Avoid that scsi_forget_host() can call __scsi_remove_device()
>> while scsi_device_dev_release_usercontext() is freeing the same
>> SCSI device.
>> ---
>>  drivers/scsi/scsi_scan.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
>> index e0a78f5..6cffc90 100644
>> --- a/drivers/scsi/scsi_scan.c
>> +++ b/drivers/scsi/scsi_scan.c
>> @@ -1890,10 +1890,11 @@ void scsi_forget_host(struct Scsi_Host *shost)
>>   restart:
>>  	spin_lock_irqsave(shost->host_lock, flags);
>>  	list_for_each_entry(sdev, &shost->__devices, siblings) {
>> -		if (sdev->sdev_state == SDEV_DEL)
>> +		if (sdev->sdev_state == SDEV_DEL || scsi_device_get(sdev) < 0)
>>  			continue;
>>  		spin_unlock_irqrestore(shost->host_lock, flags);
>>  		__scsi_remove_device(sdev);
>> +		scsi_device_put(sdev);
>>  		goto restart;
>>  	}
>>  	spin_unlock_irqrestore(shost->host_lock, flags);
>> --
>> 2.9.2
>>
>>
>>
> Hello Bart, Johannes
>
> I will test this as well.
> I have lost my DDN array today (sadly:)) but I have two systems back to back again using ramdisk on the one to serve LUNS.
>
> If I pull from  https://github.com/bvanassche/linux again, and switch branch to srp-initiator-for-next, will I get all Mikes latest patches from last week + this.
> I guess I can just check myself, but might as well just ask.

Hello Laurence,

The above patch is not yet available on my srp-initiator-for-next 
branch. I will push out that patch later today after it has been tested.

Bart.