From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 98D144CDA15 for ; Wed, 16 Sep 2026 22:48:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789598941; cv=none; b=DkLItC5+qH3dZTWjJ2+M7eySvZc7Uuit6WqhD8fSu/PtnUgbAABzizT5EXDxkX7rDry3H6uSCKsLy9enDVr+y6dkkOSdpiUOTq5MvlWybNPHvlPuSA02mk4Tq1SMDKcdHzc9g7JTTzfCJlNADjmQgfG0zRZ0z/F2B7XbrFJj+KY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789598941; c=relaxed/simple; bh=LjK7P4oYEB4R9HurzXoUhCxVG5E0S0iQLYMpR5wWv30=; h=Date:To:From:Subject:Message-Id; b=Wr1bq3srMxiV/8rP3IAHhgvEOgWoo5Ab81nLvAqIh5apvizv9YyDFhO5Y2Vmg0pcqD9UEJcrkQUY5P4XheK5UjcjN9qmGe570lT/i78wuKVbplTvjS7wlpSr8vbiLh7r9HuVRxiTaW/VDZUFz3cJ3XSIyXOPUB5XXN7Bep2g0/U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=T1grLMWi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="T1grLMWi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1917E1F00898; Wed, 16 Sep 2026 22:48:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789598931; bh=Bqwc25OxNAZ+eo3mmL4KlQWpQ7apsEY6rH7YcPZ4ozU=; h=Date:To:From:Subject; b=T1grLMWiFJwN6eBd6+lIaj2T0d/1KrAVrL2xKNknvhukPFZ+db3gY5W6NSaJAnSP9 HUrDiE9r23bvCdwDhCpEMR9y6RrmB3bBQQovJqMa9UhJBlwulm4OYZEPf360oj/cSf MAMXP4ET7EeAdONu/78KMoEQGlMolnHQ775ZMXSM= Date: Wed, 16 Sep 2026 15:48:50 -0700 To: mm-commits@vger.kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-collapse-add-collapseh-for-the-collapse-interface.patch added to mm-unstable branch Message-Id: <20260916224851.1917E1F00898@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/collapse: add collapse.h for the collapse interface has been added to the -mm mm-unstable branch. Its filename is mm-collapse-add-collapseh-for-the-collapse-interface.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-collapse-add-collapseh-for-the-collapse-interface.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Kiryl Shutsemau (Meta)" Subject: mm/collapse: add collapse.h for the collapse interface Date: Wed, 16 Sep 2026 10:31:31 +0100 khugepaged.c holds both the users of collapse and the machinery that performs it. The daemon's scan loop, the sysfs tunables, MADV_COLLAPSE's entry point and the collapse itself all sit in one file and reach into each other freely. Nothing marks where a user ends and the engine begins. Start drawing that line. Add mm/collapse.h for what the two sides have to agree on: - enum scan_result - what the engine hands back; - struct collapse_control - the state a request carries. And two constants move with them: - KHUGEPAGED_MAX_PTES_LIMIT -> COLLAPSE_MAX_PTES_LIMIT; - KHUGEPAGED_MIN_MTHP_ORDER -> COLLAPSE_MIN_MTHP_ORDER. Neither is a fact about the daemon, so both lose the KHUGEPAGED_ prefix. No functional change. Assisted-by: LLM Link: https://lore.kernel.org/20260916093145.4022188-5-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) Signed-off-by: Andrew Morton Reviewed-by: Zi Yan Reviewed-by: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Jann Horn Cc: Lance Yang Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Ryan Roberts Cc: Vlastimil Babka --- MAINTAINERS | 1 mm/collapse.h | 64 +++++++++++++++++++++++++++++++++++++ mm/khugepaged.c | 79 +++++++--------------------------------------- 3 files changed, 78 insertions(+), 66 deletions(-) --- a/MAINTAINERS~mm-collapse-add-collapseh-for-the-collapse-interface +++ a/MAINTAINERS @@ -17433,6 +17433,7 @@ F: Documentation/admin-guide/mm/transhug F: include/linux/huge_mm.h F: include/linux/khugepaged.h F: include/trace/events/huge_memory.h +F: mm/collapse.h F: mm/huge_memory.c F: mm/khugepaged.c F: mm/mm_slot.h diff --git a/mm/collapse.h a/mm/collapse.h new file mode 100644 --- /dev/null +++ a/mm/collapse.h @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __MM_COLLAPSE_H +#define __MM_COLLAPSE_H + +#include +#include +#include +#include + +#define COLLAPSE_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1) +#define COLLAPSE_MIN_MTHP_ORDER 2 + +enum scan_result { + SCAN_FAIL, + SCAN_SUCCEED, + SCAN_NO_PTE_TABLE, + SCAN_PMD_MAPPED, + SCAN_EXCEED_NONE_PTE, + SCAN_EXCEED_SWAP_PTE, + SCAN_EXCEED_SHARED_PTE, + SCAN_PTE_NON_PRESENT, + SCAN_PTE_UFFD, + SCAN_PTE_MAPPED_HUGEPAGE, + SCAN_LACK_REFERENCED_PAGE, + SCAN_PAGE_NULL, + SCAN_SCAN_ABORT, + SCAN_PAGE_COUNT, + SCAN_PAGE_LRU, + SCAN_PAGE_LOCK, + SCAN_PAGE_ANON, + SCAN_PAGE_LAZYFREE, + SCAN_PAGE_COMPOUND, + SCAN_ANY_PROCESS, + SCAN_VMA_NULL, + SCAN_VMA_CHECK, + SCAN_ADDRESS_RANGE, + SCAN_DEL_PAGE_LRU, + SCAN_ALLOC_HUGE_PAGE_FAIL, + SCAN_CGROUP_CHARGE_FAIL, + SCAN_TRUNCATED, + SCAN_PAGE_HAS_PRIVATE, + SCAN_STORE_FAILED, + SCAN_COPY_MC, + SCAN_PAGE_FILLED, + SCAN_PAGE_DIRTY_OR_WRITEBACK, +}; + +struct collapse_control { + bool is_khugepaged; + + /* Num pages scanned per node */ + u32 node_load[MAX_NUMNODES]; + + /* Num pages scanned (see khugepaged_pages_to_scan) */ + unsigned int progress; + + /* nodemask for allocation fallback */ + nodemask_t alloc_nmask; + + /* Each bit marks a PTE the scan accepted as a collapse source */ + DECLARE_BITMAP(eligible_ptes, MAX_PTRS_PER_PTE); +}; + +#endif /* __MM_COLLAPSE_H */ --- a/mm/khugepaged.c~mm-collapse-add-collapseh-for-the-collapse-interface +++ a/mm/khugepaged.c @@ -26,44 +26,10 @@ #include #include +#include "collapse.h" #include "internal.h" -#include "page_alloc.h" #include "mm_slot.h" - -enum scan_result { - SCAN_FAIL, - SCAN_SUCCEED, - SCAN_NO_PTE_TABLE, - SCAN_PMD_MAPPED, - SCAN_EXCEED_NONE_PTE, - SCAN_EXCEED_SWAP_PTE, - SCAN_EXCEED_SHARED_PTE, - SCAN_PTE_NON_PRESENT, - SCAN_PTE_UFFD, - SCAN_PTE_MAPPED_HUGEPAGE, - SCAN_LACK_REFERENCED_PAGE, - SCAN_PAGE_NULL, - SCAN_SCAN_ABORT, - SCAN_PAGE_COUNT, - SCAN_PAGE_LRU, - SCAN_PAGE_LOCK, - SCAN_PAGE_ANON, - SCAN_PAGE_LAZYFREE, - SCAN_PAGE_COMPOUND, - SCAN_ANY_PROCESS, - SCAN_VMA_NULL, - SCAN_VMA_CHECK, - SCAN_ADDRESS_RANGE, - SCAN_DEL_PAGE_LRU, - SCAN_ALLOC_HUGE_PAGE_FAIL, - SCAN_CGROUP_CHARGE_FAIL, - SCAN_TRUNCATED, - SCAN_PAGE_HAS_PRIVATE, - SCAN_STORE_FAILED, - SCAN_COPY_MC, - SCAN_PAGE_FILLED, - SCAN_PAGE_DIRTY_OR_WRITEBACK, -}; +#include "page_alloc.h" #define CREATE_TRACE_POINTS #include @@ -91,7 +57,6 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepage * * Note that these are only respected if collapse was initiated by khugepaged. */ -#define KHUGEPAGED_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1) unsigned int khugepaged_max_ptes_none __read_mostly; static unsigned int khugepaged_max_ptes_swap __read_mostly; static unsigned int khugepaged_max_ptes_shared __read_mostly; @@ -101,24 +66,6 @@ static DEFINE_READ_MOSTLY_HASHTABLE(mm_s static struct kmem_cache *mm_slot_cache __ro_after_init; -#define KHUGEPAGED_MIN_MTHP_ORDER 2 - -struct collapse_control { - bool is_khugepaged; - - /* Num pages scanned per node */ - u32 node_load[MAX_NUMNODES]; - - /* Num pages scanned (see khugepaged_pages_to_scan) */ - unsigned int progress; - - /* nodemask for allocation fallback */ - nodemask_t alloc_nmask; - - /* Each bit marks a PTE the scan accepted as a collapse source */ - DECLARE_BITMAP(eligible_ptes, MAX_PTRS_PER_PTE); -}; - /** * struct khugepaged_scan - cursor for scanning * @mm_head: the head of the mm list to scan @@ -267,7 +214,7 @@ static ssize_t max_ptes_none_store(struc unsigned long max_ptes_none; err = kstrtoul(buf, 10, &max_ptes_none); - if (err || max_ptes_none > KHUGEPAGED_MAX_PTES_LIMIT) + if (err || max_ptes_none > COLLAPSE_MAX_PTES_LIMIT) return -EINVAL; khugepaged_max_ptes_none = max_ptes_none; @@ -292,7 +239,7 @@ static ssize_t max_ptes_swap_store(struc unsigned long max_ptes_swap; err = kstrtoul(buf, 10, &max_ptes_swap); - if (err || max_ptes_swap > KHUGEPAGED_MAX_PTES_LIMIT) + if (err || max_ptes_swap > COLLAPSE_MAX_PTES_LIMIT) return -EINVAL; khugepaged_max_ptes_swap = max_ptes_swap; @@ -318,7 +265,7 @@ static ssize_t max_ptes_shared_store(str unsigned long max_ptes_shared; err = kstrtoul(buf, 10, &max_ptes_shared); - if (err || max_ptes_shared > KHUGEPAGED_MAX_PTES_LIMIT) + if (err || max_ptes_shared > COLLAPSE_MAX_PTES_LIMIT) return -EINVAL; khugepaged_max_ptes_shared = max_ptes_shared; @@ -378,19 +325,19 @@ static unsigned int collapse_max_ptes_no if (is_pmd_order(order)) return max_ptes_none; /* - * for mTHP collapse with the sysctl value set to KHUGEPAGED_MAX_PTES_LIMIT, + * for mTHP collapse with the sysctl value set to COLLAPSE_MAX_PTES_LIMIT, * scale the maximum number of PTEs to the order of the collapse. */ - if (max_ptes_none == KHUGEPAGED_MAX_PTES_LIMIT) + if (max_ptes_none == COLLAPSE_MAX_PTES_LIMIT) return (1 << order) - 1; /* - * For mTHP collapse of values other than 0 or KHUGEPAGED_MAX_PTES_LIMIT, + * For mTHP collapse of values other than 0 or COLLAPSE_MAX_PTES_LIMIT, * emit a warning and return 0. */ if (max_ptes_none) pr_warn_once("mTHP collapse does not support max_ptes_none" " values other than 0 or %u, defaulting to 0.\n", - KHUGEPAGED_MAX_PTES_LIMIT); + COLLAPSE_MAX_PTES_LIMIT); return 0; } @@ -476,7 +423,7 @@ int __init khugepaged_init(void) return -ENOMEM; khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; - khugepaged_max_ptes_none = KHUGEPAGED_MAX_PTES_LIMIT; + khugepaged_max_ptes_none = COLLAPSE_MAX_PTES_LIMIT; khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2; @@ -1571,8 +1518,8 @@ next_order: * any smaller order enabled. When at the smallest order * we must always move to the next offset. */ - if (order > KHUGEPAGED_MIN_MTHP_ORDER && - (enabled_orders & GENMASK(order - 1, 0))) { + if (order > COLLAPSE_MIN_MTHP_ORDER && + (enabled_orders & GENMASK(order - 1, 0))) { order--; continue; } @@ -1636,7 +1583,7 @@ static enum scan_result collapse_scan_pm * is then checked again in mthp_collapse() for each attempted order. */ if (enabled_orders != BIT(HPAGE_PMD_ORDER)) - max_ptes_none = KHUGEPAGED_MAX_PTES_LIMIT; + max_ptes_none = COLLAPSE_MAX_PTES_LIMIT; pte = pte_offset_map_lock(mm, pmd, start_addr, &ptl); if (!pte) { _ Patches currently in -mm which might be from kas@kernel.org are mm-huge_memory-do-not-touch-frozen-folios-in-deferred_split_isolate.patch mm-huge_memory-dequeue-the-deferred-split-after-the-split-freeze.patch mm-huge_memory-add-folio_reset_partially_mapped.patch mm-khugepaged-drop-redundant-mm_struct-pin-in-madvise_collapse.patch mm-khugepaged-count-collapses-where-khugepaged-makes-them.patch mm-khugepaged-rename-mthp_present_ptes-bitmap-to-eligible_ptes.patch mm-collapse-add-collapseh-for-the-collapse-interface.patch mm-collapse-state-what-a-collapse-may-do-in-the-policy.patch mm-collapse-drop-the-collapse_possible-wrapper.patch mm-collapse-name-the-per-table-scan-reset-for-what-it-resets.patch mm-collapse-separate-scanning-a-pte-table-from-collapsing-it.patch mm-collapse-open-code-collapse_single_pmd-in-its-two-callers.patch mm-collapse-work-out-the-orders-a-vma-allows-once-per-vma.patch mm-collapse-declare-the-collapse-interface-in-collapseh.patch mm-collapse-implement-madv_collapse-in-madvisec.patch