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Kiryl Shutsemau (Meta)
b79d51e92e
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. Link: https://lore.kernel.org/20260919002451.496763-11-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com> Assisted-by: LLM Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: "David Hildenbrand (arm)" <david@kernel.org> Cc: Dev Jain <dev.jain@arm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: kernel-team@meta.com Cc: Lance Yang <lance.yang@linux.dev> Cc: Leon Romanovsky <leon@kernel.org> Cc: Liam Howlett <liam@infradead.org> Cc: Lorenzo Stoakes (ARM) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Nico Pache (Red Hat) <nico.pache@linux.dev> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Shuah Khan (Samsung OSG) <shuah@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usama.arif@linux.dev> Cc: "Vlastimil Babka (SUSE)" <vbabka@kernel.org> Cc: Zi Yan <ziy@nvidia.com>