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

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Message-ID: <0be630f0-ce8e-4a80-b42f-697ea603cfc6@arm.com>
Date: Mon, 4 Mar 2024 09:50:31 +0000
From: Aishwarya TCV <aishwarya.tcv@....com>
To: Zi Yan <ziy@...dia.com>
Cc: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>, linux-mm@...ck.org,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 David Hildenbrand <david@...hat.com>, Yang Shi <shy828301@...il.com>,
 Yu Zhao <yuzhao@...gle.com>,
 "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
 Ryan Roberts <ryan.roberts@....com>, Michal Koutný
 <mkoutny@...e.com>, Roman Gushchin <roman.gushchin@...ux.dev>,
 Zach O'Keefe <zokeefe@...gle.com>, Hugh Dickins <hughd@...gle.com>,
 Luis Chamberlain <mcgrof@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org,
 cgroups@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 linux-kselftest@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v5 8/8] mm: huge_memory: enable debugfs to split huge
 pages to any order.



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@...dia.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@...dia.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.


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>[  639.821657] split_huge_page (111099): drop_caches: 3
<6>[  639.821657] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 4 # SKIP Pagecache folio split skipped
<6>[  645.392184] split_huge_page (111099): drop_caches: 3
<6>[  645.392184] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 5 # SKIP Pagecache folio split skipped
<6>[  650.938248] split_huge_page (111099): drop_caches: 3
<6>[  650.938248] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 6 # SKIP Pagecache folio split skipped
<6>[  656.500149] split_huge_page (111099): drop_caches: 3
<6>[  656.500149] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 7 # SKIP Pagecache folio split skipped
<6>[  662.044085] split_huge_page (111099): drop_caches: 3
<6>[  662.044085] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 8 # SKIP Pagecache folio split skipped
<6>[  667.591841] split_huge_page (111099): drop_caches: 3
<6>[  667.591841] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 9 # SKIP Pagecache folio split skipped
<6>[  673.172441] split_huge_page (111099): drop_caches: 3
<6>[  673.172441] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 10 # SKIP Pagecache folio split skipped
<6>[  678.726263] split_huge_page (111099): drop_caches: 3
<6>[  678.726263] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 11 # SKIP Pagecache folio split skipped
<6>[  684.272851] split_huge_page (111099): drop_caches: 3
<6>[  684.272851] split_huge_page (111099): drop_caches: 3
# # # No large pagecache folio generated, please provide a filesystem
supporting large folio
# # ok 12 # SKIP Pagecache folio split skipped
# # Bail out! cannot remove tmp dir: Directory not empty
# # # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:9 error:0
# # [FAIL]
# not ok 51 split_huge_page_test # exit=1
# # ------------------

Thanks,
Aishwarya