Date:   Thu, 29 Dec 2022 16:23:13 +0800
From:   Shiyang Ruan <ruansy.fnst@...itsu.com>
To:     Dan Williams <dan.j.williams@...el.com>, <djwong@...nel.org>,
        <david@...morbit.com>, <akpm@...ux-foundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
        <nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH v2 0/8] fsdax,xfs: fix warning messages



在 2022/12/3 9:21, Dan Williams 写道:
> Shiyang Ruan wrote:
>> Changes since v1:
>>   1. Added a snippet of the warning message and some of the failed cases
>>   2. Separated the patch for easily review
>>   3. Added page->share and its helper functions
>>   4. Included the patch[1] that removes the restrictions of fsdax and reflink
>> [1] https://lore.kernel.org/linux-xfs/1663234002-17-1-git-send-email-ruansy.fnst@fujitsu.com/
>>
...
>>
>> This also effects dax+noreflink mode if we run the test after a
>> dax+reflink test.  So, the most urgent thing is solving the warning
>> messages.
>>
>> With these fixes, most warning messages in dax_associate_entry() are
>> gone.  But honestly, generic/388 will randomly failed with the warning.
>> The case shutdown the xfs when fsstress is running, and do it for many
>> times.  I think the reason is that dax pages in use are not able to be
>> invalidated in time when fs is shutdown.  The next time dax page to be
>> associated, it still remains the mapping value set last time.  I'll keep
>> on solving it.
> 
> This one also sounds like it is going to be relevant for CXL PMEM, and
> the improvements to the reference counting. CXL has a facility where the
> driver asserts that no more writes are in-flight to the device so that
> the device can assert a clean shutdown. Part of that will be making sure
> that page access ends at fs shutdown.

I was trying to locate the root cause of the fail on generic/388.  But 
since it's a fsstress test, I can't relpay the operation sequence to 
help me locate the operations.  So, I tried to replace fsstress with 
fsx, which can do replay after the case fails, but it can't reproduce 
the fail.  I think another important factor is that fsstress tests with 
multiple threads.  So, for now, it's hard for me to locate the cause by 
running the test.

Then I updated the kernel to the latest v6.2-rc1 and run generic/388 for 
many times.  The warning dmesg doesn't show any more.

How is your test on this case?  Does it still fail on the latest kernel? 
  If so, I think I have to keep on locating the cause, and need your advice.


--
Thanks,
Ruan.

> 
>> The warning message in dax_writeback_one() can also be fixed because of
>> the dax unshare.
>>
>>
>> Shiyang Ruan (8):
>>    fsdax: introduce page->share for fsdax in reflink mode
>>    fsdax: invalidate pages when CoW
>>    fsdax: zero the edges if source is HOLE or UNWRITTEN
>>    fsdax,xfs: set the shared flag when file extent is shared
>>    fsdax: dedupe: iter two files at the same time
>>    xfs: use dax ops for zero and truncate in fsdax mode
>>    fsdax,xfs: port unshare to fsdax
>>    xfs: remove restrictions for fsdax and reflink
>>
>>   fs/dax.c                   | 220 +++++++++++++++++++++++++------------
>>   fs/xfs/xfs_ioctl.c         |   4 -
>>   fs/xfs/xfs_iomap.c         |   6 +-
>>   fs/xfs/xfs_iops.c          |   4 -
>>   fs/xfs/xfs_reflink.c       |   8 +-
>>   include/linux/dax.h        |   2 +
>>   include/linux/mm_types.h   |   5 +-
>>   include/linux/page-flags.h |   2 +-
>>   8 files changed, 166 insertions(+), 85 deletions(-)
>>
>> -- 
>> 2.38.1
>>
>>
> 
> 

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