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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Greg Thelen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 0/3] selftests: mm: introduce page allocation stall reproducer Message-Id: <20260820170348.48f04ed654dce5193ca3a532@linux-foundation.org> In-Reply-To: <20260819070538.2404983-1-jasonmiu@google.com> References: <20260819070538.2404983-1-jasonmiu@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8E7AD120003 X-Stat-Signature: ija49x6e9tdu77yinaonp3wo19c3yg45 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1787270630-809513 X-HE-Meta: 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 0aqRcGf0 5mC3t5CJoLXWU2sTaMsDi8TCV/DEr08o1RZYgxj689wOHqwJ2CXZ/vhweq7yARFtpYY6g+Dl3jjGWmOUC+f/zTLpiq3xVjGwgD/Urs7492libPTF+qm7bsbufajWgsVOFZUgze+fXVvbTSFCwaThnHoHxXL97cN9jhYDQK7WCuTp66x6pifX461tDmOjHCzpGBZNx9Qh56NXPbkYcDixv1ZM1+4EbWIvs7WpP4lhbHegbLxie+QwTRDh9sgcuKVtCNVJqNs81k3xFdZK4sCT+IWzC91Xe0YNYyuNa4k5pef4y35lqwd4uMb3ufYxHTlKwFgErvGTChNTufAk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 19 Aug 2026 00:05:35 -0700 Jason Miu wrote: > Background > ========== > Under severe system memory pressure, system unresponsiveness often > occurs due to page allocation stalls. In commit 94e0bcde055e ("mm, > page_alloc: reintroduce page allocation stall warning"), David Rientjes > introduced a warning mechanism to emit a kernel log when a page > allocation takes longer than 10 seconds. This log is used to correlate > a frozen system with the system memory state at the time of failure. > > To further debug and analyze these allocation stalls, we need a > reproducible test case. This patch series introduces a new selftest > designed to artificially mimic the severe memory pressure scenarios > seen in production, allowing us to observe the resulting allocation > stalls. Interesting. > lib/Kconfig.debug | 11 + > lib/Makefile | 1 + > lib/test_mempress_timer.c | 140 +++++++++++ > .../testing/selftests/mm/page_alloc_stall.sh | 80 ++++++ > .../selftests/mm/page_alloc_stall_pressure.py | 235 ++++++++++++++++++ > 5 files changed, 467 insertions(+) > create mode 100644 lib/test_mempress_timer.c > create mode 100644 tools/testing/selftests/mm/page_alloc_stall.sh > create mode 100644 tools/testing/selftests/mm/page_alloc_stall_pressure.py Nothing fits very well, does it? selftests is for quick tests which are run by run_kselftest.sh. You had to place it in selftests because there isn't anywhere obvious for it to live. So I suggest a brand new tools/testing/stresstests/mm. If we create this, people will jump on it and start adding things which presently reside in their personal collections. I can't say I like "mempress". Is "memory_pressure" too wordy? All of lib/test*.c shouldn't be in lib/. lib/ is for library code! Again, we put them there because people are shy about doing mkdir. Sashiko said hello: https://sashiko.dev/#/patchset/20260819070538.2404983-1-jasonmiu@google.com In [patch 1/3], s/__GFP_NOFAIL// and s/cond_resched()//.