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Tue, 31 Mar 2026 02:16:26 -0700 (PDT) X-Received: by 2002:a17:90b:1850:b0:35b:b52d:f34d with SMTP id 98e67ed59e1d1-35c2ffaffdcmr15364761a91.5.1774948586559; Tue, 31 Mar 2026 02:16:26 -0700 (PDT) Received: from redhat.com ([209.132.188.88]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35dbe6fcea1sm998457a91.16.2026.03.31.02.16.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 02:16:25 -0700 (PDT) Date: Tue, 31 Mar 2026 17:16:23 +0800 From: Li Wang To: Andrew Morton 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 Message-ID: References: <20260331040156.119158-1-liwang@redhat.com> <20260331040156.119158-2-liwang@redhat.com> <20260330222948.c2cc6544492e68ded355abca@linux-foundation.org> MIME-Version: 1.0 In-Reply-To: <20260330222948.c2cc6544492e68ded355abca@linux-foundation.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: fWboNWzEx0KkIM1P4iB8ojALRRFbxuEm8Vjl5i8wcps_1774948587 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 73FE2160004 X-Stat-Signature: 4ms8rorhwdafndzi1muusmu6ukzn1zgk X-Rspam-User: X-HE-Tag: 1774948591-846335 X-HE-Meta: U2FsdGVkX18rJJpC52u20bbyRruLAWsERea4ZCvh/kGc03YB9vIGDEGzZE7pmCHyIvnp34XT/g52uXu1SDQWKlXCWVM+48Fnu+amy5yPmOhxLxwwBR6Gv1Es90dlVcW1UuDfj4gjZ/xMtqIJnfwdGmSi+5AF2C1wxapsfK24ADg+weeT4Wi+nISgNkcnxvvGWgerzkTV4kVLwI+wJUwQyrlST+Fs+xQ2Ww29Cp5QIHIseDcbGp/iJ04j994UWKIJm+73o2gjcxWq7mCYFA0C4znaPY0H2+4LkpN7ECFKASizkPFZo+iGdYpS0dP9Oy0YkKbZ2QsWmyA9pLYhglJ0mFIFVnIYIhzG+LDBFDJuNO6C8S8iFdhmrcvkYm4BmlVMf7sPD2StGJRuEdFAVvxw2nc3Un59nS/5GU1FbAkYlnU6AaxqfCskF0C9ObgokBGNHYyxgCX/eA38nZ+mPlVrwRfw4eKt8ZBNglriXxy22BnGpCHmuhAI89iHjtIkbP8Zcn4c8fjrV9Vjn/6bHooZfRSTSJocSWm3py0rx0eFcy6UdZ6M5Yu8gVZKkoLYwARRcXkgMRDzTsKwSwispPMo8et6Qefore574px52A2Jn0HghLgkTDWM083uCcuYjmzAZSxGkghY+gs5fIH5FFEqWFMvGYxWQcMq379D2LKlBub+XRpe+2jiTp2Nl0gcs+UlrPsR1Wm1yX3OuqAQFr7LjmwzXuAYImJVD1mxVsv+SpY7oa6fy60nM9hgI0S6COg9AYD3dnEu9pNGlfUncU7rOzQ39ARjiuyAjIauiAJ8YSbomowp4VDcV236/D7+7G3wpqlcoJ8LzyE5RwkQD3RQrAG1uwO/M3HcH77UkEQKMEQihg0SEzsNQoEpXnFv60fNQwiHSoqy+A5jLleb+jWjf8gjz73ig6wEi9exJnbIr3Rk9zOA5i2by5ZId85EBVlTWxvo9pPL1xutDMYq21o 5ZCAzVxh 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 30, 2026 at 10:29:48PM -0700, Andrew Morton wrote: > On Tue, 31 Mar 2026 12:01:54 +0800 Li Wang 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 > > 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. No worries, we can hang this one as well. Let me send to kbuild ML with the two valid fix (1/4, 4/4), I will reformat them. -- Regards, Li Wang