Commit 9e014077 authored by Wei Yang's avatar Wei Yang Committed by Andrew Morton
Browse files

mm/khugepaged: unify SCAN_PMD_NONE and SCAN_PMD_NULL into SCAN_NO_PTE_TABLE 

The current hugepage collapse scan results include two separate values,
SCAN_PMD_NONE and SCAN_PMD_NULL, which are handled identically by the
consuming code.

To reduce confusion and improve long-term maintenance, this commit merges
these two functionally equivalent states into a single, clearer
identifier: SCAN_NO_PTE_TABLE

Link: https://lkml.kernel.org/r/20251114030028.7035-4-richard.weiyang@gmail.com


Suggested-by: default avatar"David Hildenbrand (Red Hat)" <david@kernel.org>
Signed-off-by: default avatarWei Yang <richard.weiyang@gmail.com>
Reviewed-by: default avatarDev Jain <dev.jain@arm.com>
Acked-by: default avatarDavid Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarNico Pache <npache@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f1040f88

include/trace/events/huge_memory.h

+1 −2
Original line number Diff line number Diff line
@@ -10,8 +10,7 @@ 
#define SCAN_STATUS							\

	EM( SCAN_FAIL,			"failed")			\

	EM( SCAN_SUCCEED,		"succeeded")			\

	EM( SCAN_PMD_NULL,		"pmd_null")			\

	EM( SCAN_PMD_NONE,		"pmd_none")			\

	EM( SCAN_NO_PTE_TABLE,		"no_pte_table")			\

	EM( SCAN_PMD_MAPPED,		"page_pmd_mapped")		\

	EM( SCAN_EXCEED_NONE_PTE,	"exceed_none_pte")		\

	EM( SCAN_EXCEED_SWAP_PTE,	"exceed_swap_pte")		\

mm/khugepaged.c

+10 −13
Original line number Diff line number Diff line
@@ -30,8 +30,7 @@ 
enum scan_result {

	SCAN_FAIL,

	SCAN_SUCCEED,

	SCAN_PMD_NULL,

	SCAN_PMD_NONE,

	SCAN_NO_PTE_TABLE,

	SCAN_PMD_MAPPED,

	SCAN_EXCEED_NONE_PTE,

	SCAN_EXCEED_SWAP_PTE,
@@ -934,7 +933,7 @@ static inline int check_pmd_state(pmd_t *pmd) 
	pmd_t pmde = pmdp_get_lockless(pmd);



	if (pmd_none(pmde))

		return SCAN_PMD_NONE;

		return SCAN_NO_PTE_TABLE;



	/*

	 * The folio may be under migration when khugepaged is trying to
@@ -944,11 +943,11 @@ static inline int check_pmd_state(pmd_t *pmd) 
	if (pmd_is_migration_entry(pmde))

		return SCAN_PMD_MAPPED;

	if (!pmd_present(pmde))

		return SCAN_PMD_NULL;

		return SCAN_NO_PTE_TABLE;

	if (pmd_trans_huge(pmde))

		return SCAN_PMD_MAPPED;

	if (pmd_bad(pmde))

		return SCAN_PMD_NULL;

		return SCAN_NO_PTE_TABLE;

	return SCAN_SUCCEED;

}
@@ -958,7 +957,7 @@ static int find_pmd_or_thp_or_none(struct mm_struct *mm, 
{

	*pmd = mm_find_pmd(mm, address);

	if (!*pmd)

		return SCAN_PMD_NULL;

		return SCAN_NO_PTE_TABLE;



	return check_pmd_state(*pmd);

}
@@ -1013,7 +1012,7 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, 
			pte = pte_offset_map_ro_nolock(mm, pmd, addr, &ptl);

			if (!pte) {

				mmap_read_unlock(mm);

				result = SCAN_PMD_NULL;

				result = SCAN_NO_PTE_TABLE;

				goto out;

			}

		}
@@ -1187,7 +1186,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, 
						      &compound_pagelist);

		spin_unlock(pte_ptl);

	} else {

		result = SCAN_PMD_NULL;

		result = SCAN_NO_PTE_TABLE;

	}



	if (unlikely(result != SCAN_SUCCEED)) {
@@ -1270,7 +1269,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, 
	nodes_clear(cc->alloc_nmask);

	pte = pte_offset_map_lock(mm, pmd, start_addr, &ptl);

	if (!pte) {

		result = SCAN_PMD_NULL;

		result = SCAN_NO_PTE_TABLE;

		goto out;

	}
@@ -1544,8 +1543,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, 
	switch (result) {

	case SCAN_SUCCEED:

		break;

	case SCAN_PMD_NULL:

	case SCAN_PMD_NONE:

	case SCAN_NO_PTE_TABLE:

		/*

		 * All pte entries have been removed and pmd cleared.

		 * Skip all the pte checks and just update the pmd mapping.
@@ -2832,8 +2830,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, 
			mmap_read_unlock(mm);

			goto handle_result;

		/* Whitelisted set of results where continuing OK */

		case SCAN_PMD_NULL:

		case SCAN_PMD_NONE:

		case SCAN_NO_PTE_TABLE:

		case SCAN_PTE_NON_PRESENT:

		case SCAN_PTE_UFFD_WP:

		case SCAN_LACK_REFERENCED_PAGE: