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mm/khugepaged: change collapse_pte_mapped_thp() to return void

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The only external caller of collapse_pte_mapped_thp() is uprobe, which
ignores the return value.  Change the external API to return void to
simplify the interface.

Introduce try_collapse_pte_mapped_thp() for internal use that preserves
the return value.  This prepares for future patch that will convert the
return type to use enum scan_result.

Link: https://lkml.kernel.org/r/20260118192253.9263-10-shivankg@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Tested-by: Nico Pache <npache@redhat.com>
Reviewed-by: Nico Pache <npache@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Shivank Garg 2026-01-18 19:22:57 +00:00 committed by Andrew Morton
parent 7832e4d583
commit 3ab981c1fc
2 changed files with 27 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/khugepaged.h
View File

@ -17,8 +17,8 @@ extern void khugepaged_enter_vma(struct vm_area_struct *vma,
vm_flags_t vm_flags);
extern void khugepaged_min_free_kbytes_update(void);
extern bool current_is_khugepaged(void);
extern int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
bool install_pmd);
void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
bool install_pmd);
static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
@ -42,10 +42,9 @@ static inline void khugepaged_enter_vma(struct vm_area_struct *vma,
vm_flags_t vm_flags)
{
}
static inline int collapse_pte_mapped_thp(struct mm_struct *mm,
unsigned long addr, bool install_pmd)
static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
unsigned long addr, bool install_pmd)
{
return 0;
}
static inline void khugepaged_min_free_kbytes_update(void)

40
mm/khugepaged.c
View File

@ -1477,20 +1477,8 @@ static int set_huge_pmd(struct vm_area_struct *vma, unsigned long addr,
return SCAN_SUCCEED;
}
/**
* collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at
* address haddr.
*
* @mm: process address space where collapse happens
* @addr: THP collapse address
* @install_pmd: If a huge PMD should be installed
*
* This function checks whether all the PTEs in the PMD are pointing to the
* right THP. If so, retract the page table so the THP can refault in with
* as pmd-mapped. Possibly install a huge PMD mapping the THP.
*/
int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
bool install_pmd)
static int try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
bool install_pmd)
{
int nr_mapped_ptes = 0, result = SCAN_FAIL;
unsigned int nr_batch_ptes;
@ -1711,6 +1699,24 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
return result;
}
/**
* collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at
* address haddr.
*
* @mm: process address space where collapse happens
* @addr: THP collapse address
* @install_pmd: If a huge PMD should be installed
*
* This function checks whether all the PTEs in the PMD are pointing to the
* right THP. If so, retract the page table so the THP can refault in with
* as pmd-mapped. Possibly install a huge PMD mapping the THP.
*/
void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
bool install_pmd)
{
try_collapse_pte_mapped_thp(mm, addr, install_pmd);
}
/* Can we retract page tables for this file-backed VMA? */
static bool file_backed_vma_is_retractable(struct vm_area_struct *vma)
{
@ -2227,7 +2233,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
/*
* Remove pte page tables, so we can re-fault the page as huge.
* If MADV_COLLAPSE, adjust result to call collapse_pte_mapped_thp().
* If MADV_COLLAPSE, adjust result to call try_collapse_pte_mapped_thp().
*/
retract_page_tables(mapping, start);
if (cc && !cc->is_khugepaged)
@ -2479,7 +2485,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
mmap_read_lock(mm);
if (hpage_collapse_test_exit_or_disable(mm))
goto breakouterloop;
*result = collapse_pte_mapped_thp(mm,
*result = try_collapse_pte_mapped_thp(mm,
khugepaged_scan.address, false);
if (*result == SCAN_PMD_MAPPED)
*result = SCAN_SUCCEED;
@ -2844,7 +2850,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
case SCAN_PTE_MAPPED_HUGEPAGE:
BUG_ON(mmap_locked);
mmap_read_lock(mm);
result = collapse_pte_mapped_thp(mm, addr, true);
result = try_collapse_pte_mapped_thp(mm, addr, true);
mmap_read_unlock(mm);
goto handle_result;
/* Whitelisted set of results where continuing OK */