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Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XAg1fiJ_1789003039 cluster:ay36) by smtp.aliyun-inc.com; Thu, 10 Sep 2026 09:17:20 +0800 Message-ID: Date: Thu, 10 Sep 2026 09:17:19 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 10/19] selftests/mm: add khugepaged completion barrier helper To: Kiryl Shutsemau , akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, rppt@kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, usama.anjum@arm.com, usama.arif@linux.dev, nico.pache@linux.dev, ziy@nvidia.com, baohua@kernel.org, dev.jain@arm.com, hughd@google.com, lance.yang@linux.dev, liam@infradead.org, mhocko@suse.com, ryan.roberts@arm.com, shuah@kernel.org, surenb@google.com, vbabka@kernel.org, agordeev@linux.ibm.com, jgg@ziepe.ca, leon@kernel.org, kernel-team@meta.com, "Kiryl Shutsemau (Meta)" References: <20260908125105.1510704-1-kirill@shutemov.name> <20260908125105.1510704-11-kirill@shutemov.name> From: Baolin Wang In-Reply-To: <20260908125105.1510704-11-kirill@shutemov.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 44BBC40006 X-Stat-Signature: 57s7wzbc5frq8ezhqm9rfcawik9jpehg X-Rspam-User: X-HE-Tag: 1789003044-9214 X-HE-Meta: U2FsdGVkX19OsUPPVdpdxTnHXYGyHcSzKuevIO0cXg56Wwh3vt7/kIWHzXyyB0ivwaJ8uhLOOaPc4FxW9NZgzr4lFvkfNOuF999+xHTPU5wI7cpk3zwm3ZOYZLCIxHDf8D1tG2WUm00m4Hzg17RQM+Vj0oSJTRenIJcOVYQktEXGcXlGPP25wbLRl9wjzQBtBinMY2fqNWgJq4fNMlqcD5ivLQtbTEjp8ZobpgqXHzEid90V5QBQ1kJ6ftxRA4YJDoESgOc5x6xUtxKLXD/cVLX7G0f4n1p2YGHPiGIE68LmoQONKNHvLs/oDsTEZznp45qtlq1KtF5X07pjsaOwJrVxmC7JSw2KO0Bbc86RTwk8uNdoHWTertn61F+Lji43sdjAprBqVWcBYH0BrtiSuDjDhe9l59+nVvXF4qaQU2boRf9i2NinmvQla/HUHdqg0GGFus31B+XrQc0H1VwkbNeMFc7MjpTdH0lGU2JqtOUDNlyVp2g4zQ55ZlN96T3dehj+dfelYptiza/8TuIOMfpP3ou49RnRWZWyUtcFtLKjZ4as2ybc0O/uXv6b2M54CpygqWLhGLZCmHIm/bPyVEvta6mkUx+hTMgPleUEBWYBh6cQgqsACWgAxYxiRgm01HY4RWoUngHULwPG5JhxZPJuHM9WSH5lY9jEU4X7ZgV67psRnsdyYvmtPVOBhoGXbk/Jx76Xn/3LZuWEZCHM523/2hyQm3MCnlaoOAc2OCO4gft/dPuq3VFWHpgK/0N4xCagLQIl2PcVVgtbp72csP0U+umG2jsXVQahWeoJ4osF0X6RfvbObpPMggEI9KMQA2JvbZtDdYh+yjftJQl3OAmWQyVQgLnCQ1kTRZDG/u3Ex88R9jCqYpcZwPvOsyT5kW41O0Tq8CtrnmH3TYEzftmGdhut99K4KbQMOhlbuPgALmDJG7t/XghELk51iGvwh+JzzhArCXJUBHzxtkz Bwl5kMYb hutrOnc3diEkVSfnfv+pAolMHrLDY5ZzAyzOE1UdeqLfETbgqLE1ltMcGV765YcVeyAY7kipLomhvjgZPHm+JYKqVqbGvsJX5kdZMFTOazVfFYUMvtrPrpSBkZwvNnJNHP7eId4hfffrd3JpxJ6+fBso798//mOyZRvAWCBrPp/11x8p3KeBN3JkjJP+MTnZK+u9DajSFvgUL6vAFc+7m0RHJKpzUcq4DLd2Eg36aKmjL+jttEzQad0C/VdTjdDcTfioKJJ3up3+IdlT6zgAYu9PkQtremhRuOfX6HCTfRnxumwTfCnSPYTk3Tyfz6nULOXCGI45BUq+E6HUW34L4shCB5ceNOCRFDWGyu2zQ7tWXmRNdXzKofq1h9VEVGPEbh9/n Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/8/26 8:50 PM, Kiryl Shutsemau wrote: > From: "Kiryl Shutsemau (Meta)" > > A khugepaged test has to tell "not collapsed" from "not scanned yet", and > nothing in the selftests can. wait_for_scan() in khugepaged.c comes > closest: it polls full_scans until the counter has advanced by two, since > the pass in progress may already have passed the test's mm. But it only > returns in time if scan_sleep_millisecs happens to be short, and it is > private to that one test. > > Add khugepaged_full_pass() to hugepage_settings, built on the same > advance-by-two wait but driven through sysfs: a store to > scan_sleep_millisecs wakes the daemon, so the barrier completes whatever > the scan cadence. A store made while the daemon is scanning rather than > sleeping is lost, so the helper keeps storing until the pass lands. > > One wake completes one pass only if pages_to_scan covers every mm on the > list, so callers need it large. > > Settings pushes must not start passes of their own. A store to either > sleep knob wakes the daemon, so thp_write_settings() now writes a > khugepaged knob only when its value changes. > > Assisted-by: LLM > Tested-by: Muhammad Usama Anjum > Signed-off-by: Kiryl Shutsemau (Meta) > --- Make sense to me. Reviewed-by: Baolin Wang