linux-kernel - Re: [PATCH v7 4/8] pagemap,pmem: Introduce ->memory

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Date:   Wed, 20 Oct 2021 13:25:51 +0800
From:   Shiyang Ruan <ruansy.fnst@...itsu.com>
To:     "Darrick J. Wong" <djwong@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
        <nvdimm@...ts.linux.dev>, <linux-mm@...ck.org>,
        <linux-fsdevel@...r.kernel.org>, <dan.j.williams@...el.com>,
        <david@...morbit.com>, <hch@...radead.org>, <jane.chu@...cle.com>
Subject: Re: [PATCH v7 4/8] pagemap,pmem: Introduce ->memory_failure()



在 2021/10/15 2:05, Darrick J. Wong 写道:
> On Fri, Sep 24, 2021 at 09:09:55PM +0800, Shiyang Ruan wrote:
>> When memory-failure occurs, we call this function which is implemented
>> by each kind of devices.  For the fsdax case, pmem device driver
>> implements it.  Pmem device driver will find out the filesystem in which
>> the corrupted page located in.
>>
>> With dax_holder notify support, we are able to notify the memory failure
>> from pmem driver to upper layers.  If there is something not support in
>> the notify routine, memory_failure will fall back to the generic hanlder.
>>
>> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
>> ---
>>   drivers/nvdimm/pmem.c    | 11 +++++++++++
>>   include/linux/memremap.h |  9 +++++++++
>>   mm/memory-failure.c      | 14 ++++++++++++++
>>   3 files changed, 34 insertions(+)
>>
>> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
>> index 72de88ff0d30..0dfafad8fcc5 100644
>> --- a/drivers/nvdimm/pmem.c
>> +++ b/drivers/nvdimm/pmem.c
>> @@ -362,9 +362,20 @@ static void pmem_release_disk(void *__pmem)
>>   	del_gendisk(pmem->disk);
>>   }
>>   
>> +static int pmem_pagemap_memory_failure(struct dev_pagemap *pgmap,
>> +		unsigned long pfn, size_t size, int flags)
>> +{
>> +	struct pmem_device *pmem =
>> +			container_of(pgmap, struct pmem_device, pgmap);
>> +	loff_t offset = PFN_PHYS(pfn) - pmem->phys_addr - pmem->data_offset;
>> +
>> +	return dax_holder_notify_failure(pmem->dax_dev, offset, size, flags);
>> +}
>> +
>>   static const struct dev_pagemap_ops fsdax_pagemap_ops = {
>>   	.kill			= pmem_pagemap_kill,
>>   	.cleanup		= pmem_pagemap_cleanup,
>> +	.memory_failure		= pmem_pagemap_memory_failure,
>>   };
>>   
>>   static int pmem_attach_disk(struct device *dev,
>> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
>> index c0e9d35889e8..36d47bacd46d 100644
>> --- a/include/linux/memremap.h
>> +++ b/include/linux/memremap.h
>> @@ -87,6 +87,15 @@ struct dev_pagemap_ops {
>>   	 * the page back to a CPU accessible page.
>>   	 */
>>   	vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
>> +
>> +	/*
>> +	 * Handle the memory failure happens on a range of pfns.  Notify the
>> +	 * processes who are using these pfns, and try to recover the data on
>> +	 * them if necessary.  The flag is finally passed to the recover
>> +	 * function through the whole notify routine.
>> +	 */
>> +	int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn,
>> +			      size_t size, int flags);
>>   };
>>   
>>   #define PGMAP_ALTMAP_VALID	(1 << 0)
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index 8ff9b52823c0..85eab206b68f 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1605,6 +1605,20 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
>>   	if (!pgmap_pfn_valid(pgmap, pfn))
>>   		goto out;
>>   
>> +	/*
>> +	 * Call driver's implementation to handle the memory failure, otherwise
>> +	 * fall back to generic handler.
>> +	 */
>> +	if (pgmap->ops->memory_failure) {
>> +		rc = pgmap->ops->memory_failure(pgmap, pfn, PAGE_SIZE, flags);
>> +		/*
>> +		 * Fall back to generic handler too if operation is not
>> +		 * supported inside the driver/device/filesystem.
>> +		 */
>> +		if (rc != EOPNOTSUPP)
> 
> -EOPNOTSUPP?  (negative errno)

Yes, my mistake. Thanks for pointing out.


--
Thanks,
Ruan.

> 
> --D
> 
>> +			goto out;
>> +	}
>> +
>>   	rc = mf_generic_kill_procs(pfn, flags, pgmap);
>>   out:
>>   	/* drop pgmap ref acquired in caller */
>> -- 
>> 2.33.0
>>
>>
>>