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Message-ID: <87edhtaksf.fsf@yhuang6-desk2.ccr.corp.intel.com>
Date: Tue, 17 Oct 2023 13:18:56 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: "Verma, Vishal L" <vishal.l.verma@...el.com>
Cc: "Williams, Dan J" <dan.j.williams@...el.com>,
"Jiang, Dave" <dave.jiang@...el.com>,
"osalvador@...e.de" <osalvador@...e.de>,
"david@...hat.com" <david@...hat.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"aneesh.kumar@...ux.ibm.com" <aneesh.kumar@...ux.ibm.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>,
"Hocko, Michal" <mhocko@...e.com>,
"nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
"jmoyer@...hat.com" <jmoyer@...hat.com>,
"Jonathan.Cameron@...wei.com" <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH v5 2/2] dax/kmem: allow kmem to add memory with
memmap_on_memory
"Verma, Vishal L" <vishal.l.verma@...el.com> writes:
> On Thu, 2023-10-05 at 14:16 -0700, Dan Williams wrote:
>> Vishal Verma wrote:
>> >
> <..>
>
>> > +
>> > + rc = kstrtobool(buf, &val);
>> > + if (rc)
>> > + return rc;
>>
>> Perhaps:
>>
>> if (dev_dax->memmap_on_memory == val)
>> return len;
>>
>> ...and skip the check below when it is going to be a nop
>>
>> > +
>> > + device_lock(dax_region->dev);
>> > + if (!dax_region->dev->driver) {
>>
>> Is the polarity backwards here? I.e. if the device is already attached to
>> the kmem driver it is too late to modify memmap_on_memory policy.
>
> Hm this sounded logical until I tried it. After a reconfigure-device to
> devdax (i.e. detach kmem), I get the -EBUSY if I invert this check.
Can you try to unbind the device via sysfs by hand and retry?
--
Best Regards,
Huang, Ying
>>
>> > + device_unlock(dax_region->dev);
>> > + return -ENXIO;
>>
[snip]
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