From: Andrew Morton <akpm@linux-foundation.org>
To: Li Wang <liwang@redhat.com>
Cc: david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com,
vbabka@kernel.org, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, shuah@kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] selftests/mm: serialize local_config generation for parallel builds
Date: Mon, 30 Mar 2026 22:29:48 -0700 [thread overview]
Message-ID: <20260330222948.c2cc6544492e68ded355abca@linux-foundation.org> (raw)
In-Reply-To: <20260331040156.119158-2-liwang@redhat.com>
On Tue, 31 Mar 2026 12:01:54 +0800 Li Wang <liwang@redhat.com> wrote:
> The mm selftests generate both local_config.mk and local_config.h from
> check_config.sh. With high parallelism (-jN), this can race and lead to
> incomplete target builds (e.g. only a few binaries get built after
> 'make -j100', while 'make -j1' builds everything).
>
> Switch to a stamp-based dependency:
>
> local_config.stamp: check_config.sh
> ... run check_config.sh ...
> touch local_config.stamp
>
> and make local_config.mk/local_config.h depend on the stamp.
>
> This ensures check_config.sh is executed once per update decision and
> removes the parallel race window. Also hook local_config.stamp into
> EXTRA_CLEAN.
>
> No functional change intended for non-parallel builds.
>
> Reported-by: Andrew Morton <akpm@linux-foundation.org>
Well, the wind changed direction. I saw this race a single time today
but now I'm trying to produce a reliable before-and-after report, it
isn't cooperating - everything is now building with -j100 with and
without this patch.
So not very helpful, sorry.
next prev parent reply other threads:[~2026-03-31 5:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-31 4:01 [PATCH 1/4] selftests/mm: respect build verbosity settings for 32/64-bit targets Li Wang
2026-03-31 4:01 ` [PATCH 2/4] selftests/mm: serialize local_config generation for parallel builds Li Wang
2026-03-31 5:29 ` Andrew Morton [this message]
2026-03-31 9:16 ` Li Wang
2026-03-31 4:01 ` [PATCH 3/4] selftests/lib.mk: set PWD from CURDIR to avoid wrong extmod path Li Wang
2026-03-31 5:30 ` Andrew Morton
2026-03-31 7:19 ` Li Wang
2026-03-31 4:01 ` [PATCH 4/4] selftests/mm: fix cow/gup_longterm link failures when liburing flags are missing Li Wang
2026-03-31 7:13 ` Li Wang
2026-04-01 13:44 ` David Hildenbrand (Arm)
2026-03-31 5:29 ` [PATCH 1/4] selftests/mm: respect build verbosity settings for 32/64-bit targets Andrew Morton
2026-03-31 9:50 ` Li Wang
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