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 8E7BC49B5B8 for ; Thu, 10 Sep 2026 21:55:57 +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=1789077359; cv=none; b=PREqxcBian/dIItgMLKURwA9cgvgLbQzXrFZOi7C0S6ZfeTLsaB+TLFraTvaI36GQKN8jE+LPOcHYOlmG2EV5a28ahyLV2hbo2Van1y87Req6BP22LOXjOonI7hAkMRlBPSxKBA01skZVMzXDhQuL2ulUENFZRUzLMM1HUKnCyg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789077359; c=relaxed/simple; bh=qF8vHsHiVKfxkH+SjaFHMtzasMiYc8gHGAxWXH+njZU=; h=Date:To:From:Subject:Message-Id; b=uUVldyP4DFr5kP4AZwZ7qRGJA/w6YuKC3n7nLeRt7plLyXDxn6olQdkWgpT3a4jwgJ2yJLPyOXL1lqiPdTuNmlgK7GUnUHzvh6AuMT6tanq3G8xsaoDjnDRybtXo+YCLTy+5QcbLgnu1K1+nkoPOC9OnH0wQA0WNTf+5gkcmxqk= 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=bLfT6UYG; 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="bLfT6UYG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46BFB1F000FF; Thu, 10 Sep 2026 21:55:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789077357; bh=1tXKPd8ehT3FeGjKsWDAUsdinHevau+yeD7aN3Iw2i8=; h=Date:To:From:Subject; b=bLfT6UYGEbH/WtPePHoT8pjgp6pMdj0URuYoYM8k64Hz5pzx4RkPaY0g2OvkLFMa4 84R/nboutDUFHh+Eei2451Rt3qDi5UisiGHDKs5Ox8GWewohV1zjm4ocafvbX15TWy CO1McInmggXyl5LrQQcMTeqFfSdxprzoH1NuuTUk= Date: Thu, 10 Sep 2026 14:55:56 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,vbabka@kernel.org,ryan.roberts@arm.com,ljs@kernel.org,liam@infradead.org,lance.yang@linux.dev,jannh@google.com,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@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-new branch Message-Id: <20260910215557.46BFB1F000FF@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-new 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-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next 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: Thu, 10 Sep 2026 13:02:24 +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/20260910120238.2529819-5-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) 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 Signed-off-by: Andrew Morton --- 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 @@ -17434,6 +17434,7 @@ 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