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.
Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org>
Signed-off-by: Shivank Garg <shivankg@amd.com>
---
include/linux/khugepaged.h | 9 ++++-----
mm/khugepaged.c | 40 ++++++++++++++++++++++----------------
2 files changed, 27 insertions(+), 22 deletions(-)
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index eb1946a70cff..37b992b22bba 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -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);
+extern 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)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 0b549c3250f9..04ff0730c9a1 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -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;
@@ -2869,7 +2875,7 @@ 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 */
--
2.43.0On 12/24/25 12:13, Shivank Garg wrote: > 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. > > Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org> > Signed-off-by: Shivank Garg <shivankg@amd.com> > --- > include/linux/khugepaged.h | 9 ++++----- > mm/khugepaged.c | 40 ++++++++++++++++++++++---------------- > 2 files changed, 27 insertions(+), 22 deletions(-) > > diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h > index eb1946a70cff..37b992b22bba 100644 > --- a/include/linux/khugepaged.h > +++ b/include/linux/khugepaged.h > @@ -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); > +extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, > + bool install_pmd); Sorry for late review. We remove the "extern" whenever we touch functions. Nit: two tab indent on second parameter line. Same applies for the other code you touch below (if you already adjust that line, just indent with two tabs). Acked-by: David Hildenbrand (Red Hat) <david@kernel.org> -- Cheers David
On 1/16/2026 5:18 AM, David Hildenbrand (Red Hat) wrote: > On 12/24/25 12:13, Shivank Garg wrote: >> 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. >> >> Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org> >> Signed-off-by: Shivank Garg <shivankg@amd.com> >> --- >> include/linux/khugepaged.h | 9 ++++----- >> mm/khugepaged.c | 40 ++++++++++++++++++++++---------------- >> 2 files changed, 27 insertions(+), 22 deletions(-) >> >> diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h >> index eb1946a70cff..37b992b22bba 100644 >> --- a/include/linux/khugepaged.h >> +++ b/include/linux/khugepaged.h >> @@ -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); >> +extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, >> + bool install_pmd); > > > Sorry for late review. > > We remove the "extern" whenever we touch functions. > > Nit: two tab indent on second parameter line. Same applies for the other code you touch below (if you already adjust that line, just indent with two tabs). > > > Acked-by: David Hildenbrand (Red Hat) <david@kernel.org> > Thank you for the review. I've always been unsure about when to use two-tab indent versus aligning with the opening bracket. I'll follow the two-tab indent convention going forward. I have incorporated these reviews in V3 here: https://lore.kernel.org/linux-mm/20260118192253.9263-4-shivankg@amd.com Best Regards, Shivank
On 24 Dec 2025, at 6:13, Shivank Garg wrote: > 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. > > Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org> > Signed-off-by: Shivank Garg <shivankg@amd.com> > --- > include/linux/khugepaged.h | 9 ++++----- > mm/khugepaged.c | 40 ++++++++++++++++++++++---------------- > 2 files changed, 27 insertions(+), 22 deletions(-) > LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com> -- Best Regards, Yan, Zi
On 2025/12/24 19:13, Shivank Garg wrote: > 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. > > Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org> > Signed-off-by: Shivank Garg <shivankg@amd.com> > --- Looks good overall, thanks! Acked-by: Lance Yang <lance.yang@linux.dev>
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