From: "Theodore Ts'o" <tytso@mit.edu>
To: Zorro Lang <zlang@kernel.org>
Cc: linux-ext4@vger.kernel.org, fstests@vger.kernel.org,
regressions@lists.linux.dev, Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [fstests generic/388, 455, 475, 482 ...] Ext4 journal recovery test fails
Date: Mon, 4 Sep 2023 02:08:19 -0400 [thread overview]
Message-ID: <20230904060819.GB701295@mit.edu> (raw)
In-Reply-To: <ZPTvIb6hwIjY7T2M@mit.edu>
#regzbot introduced: 8147c4c4546f9f05ef03bb839b741473b28bb560 ^
OK, I've isolated the regression of generic/455 failing with ext4/1k
to this commit, which came in via the mm tree. Nothing seems
*obviously* wrong, but I'm not sure if there are any differences in
the semantics of the new folio functions such as kmap_local_folio,
offset_in_folio, set_folio_bh() which might be making a difference.
Using kvm-xfstests[1] I bisected this via the command:
% install-kconfig ; kbuild ; kvm-xfstests -c ext4/1k -C 10 generic/455
[1] https://github.com/tytso/xfstests-bld/blob/master/Documentation/kvm-quickstart.md
And the bisection pointed me at this commit:
commit 8147c4c4546f9f05ef03bb839b741473b28bb560 (refs/bisect/bad)
Author: Matthew Wilcox (Oracle) <willy@infradead.org>
AuthorDate: Thu Jul 13 04:55:11 2023 +0100
Commit: Andrew Morton <akpm@linux-foundation.org>
CommitDate: Fri Aug 18 10:12:30 2023 -0700
jbd2: use a folio in jbd2_journal_write_metadata_buffer()
During the bisection, I treated a commit with 3+ failures as "bad",
and 0-2 commits as "good". Running generic/455 50 times to get a
sense of the failure, with the first bad commit (8147c4c4546f), I got:
ext4/1k: 50 tests, 21 failures, 223 seconds
Flaky: generic/455: 42% (21/50)
Totals: 50 tests, 0 skipped, 21 failures, 0 errors, 223s
While with the immediately preceding commit (07811230c3cd), I got:
ext4/1k: 50 tests, 4 failures, 235 seconds
Flaky: generic/455: 8% (4/50)
Totals: 50 tests, 0 skipped, 4 failures, 0 errors, 235s
Comparing these two commits (8147c4c4546f vs 07811230c3cd) using the
ext4 with a 4k block size, I get:
ext4/4k: 50 tests, 2 failures, 365 seconds
Flaky: generic/455: 4% (2/50)
Totals: 50 tests, 0 skipped, 2 failures, 0 errors, 365s
vs
ext4/4k: 50 tests, 2 failures, 349 seconds
Flaky: generic/455: 4% (2/50)
Totals: 50 tests, 0 skipped, 2 failures, 0 errors, 349s
So issue seems to be specifically with a sub-page size block size,
since ext4/4k doesn't show any issues, while ext4/1k does.
- Ted
next prev parent reply other threads:[~2023-09-04 6:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-03 12:00 [fstests generic/388, 455, 475, 482 ...] Ext4 journal recovery test fails Zorro Lang
2023-09-03 20:40 ` Theodore Ts'o
2023-09-04 6:08 ` Theodore Ts'o [this message]
2023-09-05 22:11 ` Matthew Wilcox
2023-09-06 11:03 ` Ritesh Harjani
2023-09-06 12:38 ` Matthew Wilcox
2023-09-06 19:51 ` Matthew Wilcox
2023-09-07 2:56 ` Ritesh Harjani
2023-09-07 3:47 ` Matthew Wilcox
2023-09-07 13:35 ` Ritesh Harjani
2023-09-07 14:15 ` Matthew Wilcox
2023-09-07 14:59 ` Ritesh Harjani
2023-09-10 9:26 ` Linux regression tracking (Thorsten Leemhuis)
2023-09-11 3:43 ` Theodore Ts'o
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