Re: [PATCH v5 8/8] mm: huge_memory: enable debugfs to split huge pages to any order.

From: Aishwarya TCV <aishwarya.tcv@arm.com>
To: Zi Yan <ziy@nvidia.com>
Cc: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>,
	linux-mm@kvack.org,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	"David Hildenbrand" <david@redhat.com>,
	"Yang Shi" <shy828301@gmail.com>, "Yu Zhao" <yuzhao@google.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	"Ryan Roberts" <ryan.roberts@arm.com>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Roman Gushchin" <roman.gushchin@linux.dev>,
	"Zach O'Keefe" <zokeefe@google.com>,
	"Hugh Dickins" <hughd@google.com>,
	"Luis Chamberlain" <mcgrof@kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	"Mark Brown" <broonie@kernel.org>
Subject: Re: [PATCH v5 8/8] mm: huge_memory: enable debugfs to split huge pages to any order.
Date: Mon, 4 Mar 2024 18:25:35 +0000	[thread overview]
Message-ID: <ade0aded-a0c8-42a4-8543-1affbaff3908@arm.com> (raw)
In-Reply-To: <262E4DAA-4A78-4328-B745-1355AE356A07@nvidia.com>

On 04/03/2024 15:57, Zi Yan wrote:
> On 4 Mar 2024, at 10:44, Aishwarya TCV wrote:
> 
>> On 04/03/2024 14:58, Zi Yan wrote:
>>> On 4 Mar 2024, at 4:50, Aishwarya TCV wrote:
>>>
>>>> On 01/03/2024 21:10, Zi Yan wrote:
>>>>> On 1 Mar 2024, at 15:02, Zi Yan wrote:
>>>>>
>>>>>> On 1 Mar 2024, at 14:37, Zi Yan wrote:
>>>>>>
>>>>>>> On 1 Mar 2024, at 4:51, Aishwarya TCV wrote:
>>>>>>>
>>>>>>>> On 26/02/2024 20:55, Zi Yan wrote:
>>>>>>>>> From: Zi Yan <ziy@nvidia.com>
>>>>>>>>>
>>>>>>>>> It is used to test split_huge_page_to_list_to_order for pagecache THPs.
>>>>>>>>> Also add test cases for split_huge_page_to_list_to_order via both
>>>>>>>>> debugfs.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>>>>>>>>> ---
>>>>>>>>>  mm/huge_memory.c                              |  34 ++++--
>>>>>>>>>  .../selftests/mm/split_huge_page_test.c       | 115 +++++++++++++++++-
>>>>>>>>>  2 files changed, 131 insertions(+), 18 deletions(-)
>>>>>>>>>
>>>>>>>>
>>>>>>>> Hi Zi,
>>>>>>>>
>>>>>>>> When booting the kernel against next-master(20240228)with Arm64 on
>>>>>>>> Marvell Thunder X2 (TX2), the kselftest-mm test 'split_huge_page_test'
>>>>>>>> is failing in our CI (with rootfs over NFS). I can send the full logs if
>>>>>>>> required.
>>>>>>>>
>>>>>>>> A bisect (full log below) identified this patch as introducing the
>>>>>>>> failure. Bisected it on the tag "next-20240228" at repo
>>>>>>>> "https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git".
>>>>>>>>
>>>>>>>> This works fine on  Linux version 6.8.0-rc6
>>>>>>>
>>>>>>> Hi Aishwarya,
>>>>>>>
>>>>>>> Can you try the attached patch and see if it fixes the failure? I changed
>>>>>>> the test to accept XFS dev as input, mount XFS on a temp folder under /tmp,
>>>>>>> and skip if no XFS is mounted.
>>>>>>
>>>>>> Please try this updated one. It allows you to specify a XFS device path
>>>>>> in SPLIT_HUGE_PAGE_TEST_XFS_PATH env variable, which is passed to
>>>>>> split_huge_page_test in run_vmtests.sh. It at least allow CI/CD to run
>>>>>> the test without too much change.
>>>>>
>>>>> OK. This hopefully will be my last churn. Now split_huge_page_test accepts
>>>>> a path that is backed by XFS and run_vmtest.sh creates a XFS image in /tmp,
>>>>> mounts it in /tmp, and gives the path to split_huge_page_test. I tested
>>>>> it locally and it works. Let me know if you have any issue. Thanks.
>>>>>
>>>>> --
>>>>> Best Regards,
>>>>> Yan, Zi
>>>>
>>>> Hi Zi,
>>>>
>>>> Tested the patch by applying it on next-20240304. Logs from our CI with
>>>> rootfs over nfs is attached below. "Bail out! cannot remove tmp dir:
>>>> Directory not empty" is still observed.
>>>
>>> Hi Aishwarya,
>>>
>>> Do you have the config file for the CI kernel? And /tmp is also on nfs?
>>> Any detailed information about CI machine environment? I cannot reproduce
>>> the error locally, either on bare metal or VM. Maybe because my /tmp is
>>> not NFS mounted?
>>>
>>
>> Hi Zi,
>>
>> Please find the details below. Hope it helps.
>>
>> Do you have the config file for the CI kernel?
>> - We are using:
>> defconfig+https://github.com/torvalds/linux/blob/master/tools/testing/selftests/mm/config
>>
>> And /tmp is also on nfs?
>> - Yes
>>
>> Any detailed information about CI machine environment?
>> - We are running the test using LAVA device Cavium Thunder X2 (TX2),
>> - We have very similar rootfs as - nfsrootfs:
>> https://storage.kernelci.org/images/rootfs/debian/bullseye-kselftest/20240129.0/arm64/full.rootfs.tar.xz
>> - We are using grub boot method over nfs
>> - Additionally Ryan mentioned "Looks like it is failing because he is
>> trying to delete the temp dir with rmdir() but rmdir() requires the
>> directory to be empty, which it is not."
> 
> Hi Aishwarya,
> 
> Thank you for the information and I am able to reproduce it on a NFS folder.
> The error comes from that the opened test files are not munmapped and their
> file descriptors are not closed in the skip path. NFS creates .nfsXXX files
> for them, making the temp folder not empty.
> 
> The attached patch cleans up properly and works on a NFS folder. Let me know
> if it works on your side. Thanks.
> 
> --
> Best Regards,
> Yan, Zi

Hi Zi,

Tested the attached patch on next-20240304. Confirming that the test is
running fine. Test run log is attached below.

Test run log:
# # ------------------------------
# # running ./split_huge_page_test
# # ------------------------------
# # TAP version 13
# # 1..12
# # ok 1 Split huge pages successful
# # ok 2 Split PTE-mapped huge pages successful
# # # Please enable pr_debug in split_huge_pages_in_file() for more info.
# # # Please check dmesg for more information
# # ok 3 File-backed THP split test done
<6>[ 1769.710429] split_huge_page (111119): drop_caches: 3
<6>[ 1769.710429] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 4 # SKIP Pagecache folio split skipped
<6>[ 1775.302315] split_huge_page (111119): drop_caches: 3
<6>[ 1775.302315] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 5 # SKIP Pagecache folio split skipped
<6>[ 1780.924147] split_huge_page (111119): drop_caches: 3
<6>[ 1780.924147] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 6 # SKIP Pagecache folio split skipped
<6>[ 1786.524931] split_huge_page (111119): drop_caches: 3
<6>[ 1786.524931] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 7 # SKIP Pagecache folio split skipped
<6>[ 1792.112869] split_huge_page (111119): drop_caches: 3
<6>[ 1792.112869] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 8 # SKIP Pagecache folio split skipped
<6>[ 1797.718863] split_huge_page (111119): drop_caches: 3
<6>[ 1797.718863] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 9 # SKIP Pagecache folio split skipped
<6>[ 1803.332343] split_huge_page (111119): drop_caches: 3
<6>[ 1803.332343] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 10 # SKIP Pagecache folio split skipped
<6>[ 1808.947913] split_huge_page (111119): drop_caches: 3
<6>[ 1808.947913] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 11 # SKIP Pagecache folio split skipped
<6>[ 1814.537995] split_huge_page (111119): drop_caches: 3
<6>[ 1814.537995] split_huge_page (111119): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 12 # SKIP Pagecache folio split skipped
# # # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:9 error:0
# # [PASS]
# ok 51 split_huge_page_test
# # -------------------

Thanks,
Aishwarya