The patch titled
Subject: mm/khugepaged: unify collapse pmd clear, flush and free
has been added to the -mm tree. Its filename is
mm-khugepaged-unify-collapse-pmd-clear-flush-and-free.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-khugepaged-unify-collapse-pmd-clear-flush-and-free.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-khugepaged-unify-collapse-pmd-clear-flush-and-free.patch
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------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: mm/khugepaged: unify collapse pmd clear, flush and free
Unify the code that flushes, clears pmd entry, and frees the PTE table
level into a new function collapse_and_free_pmd().
This clean-up is useful as in the next patch we will add another call to
this function to iterate through PTE prior to freeing the level for page
table check.
Link: https://lkml.kernel.org/r/20220126183637.1840960-4-pasha.tatashin@xxxxxxxxxx
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Wei Xu <weixugc@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 34 ++++++++++++++++++----------------
1 file changed, 18 insertions(+), 16 deletions(-)
--- a/mm/khugepaged.c~mm-khugepaged-unify-collapse-pmd-clear-flush-and-free
+++ a/mm/khugepaged.c
@@ -1416,6 +1416,19 @@ static int khugepaged_add_pte_mapped_thp
return 0;
}
+static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, pmd_t *pmdp)
+{
+ spinlock_t *ptl;
+ pmd_t pmd;
+
+ ptl = pmd_lock(vma->vm_mm, pmdp);
+ pmd = pmdp_collapse_flush(vma, addr, pmdp);
+ spin_unlock(ptl);
+ mm_dec_nr_ptes(mm);
+ pte_free(mm, pmd_pgtable(pmd));
+}
+
/**
* collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at
* address haddr.
@@ -1433,7 +1446,7 @@ void collapse_pte_mapped_thp(struct mm_s
struct vm_area_struct *vma = find_vma(mm, haddr);
struct page *hpage;
pte_t *start_pte, *pte;
- pmd_t *pmd, _pmd;
+ pmd_t *pmd;
spinlock_t *ptl;
int count = 0;
int i;
@@ -1509,12 +1522,7 @@ void collapse_pte_mapped_thp(struct mm_s
}
/* step 4: collapse pmd */
- ptl = pmd_lock(vma->vm_mm, pmd);
- _pmd = pmdp_collapse_flush(vma, haddr, pmd);
- spin_unlock(ptl);
- mm_dec_nr_ptes(mm);
- pte_free(mm, pmd_pgtable(_pmd));
-
+ collapse_and_free_pmd(mm, vma, haddr, pmd);
drop_hpage:
unlock_page(hpage);
put_page(hpage);
@@ -1552,7 +1560,7 @@ static void retract_page_tables(struct a
struct vm_area_struct *vma;
struct mm_struct *mm;
unsigned long addr;
- pmd_t *pmd, _pmd;
+ pmd_t *pmd;
i_mmap_lock_write(mapping);
vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
@@ -1591,14 +1599,8 @@ static void retract_page_tables(struct a
* reverse order. Trylock is a way to avoid deadlock.
*/
if (mmap_write_trylock(mm)) {
- if (!khugepaged_test_exit(mm)) {
- spinlock_t *ptl = pmd_lock(mm, pmd);
- /* assume page table is clear */
- _pmd = pmdp_collapse_flush(vma, addr, pmd);
- spin_unlock(ptl);
- mm_dec_nr_ptes(mm);
- pte_free(mm, pmd_pgtable(_pmd));
- }
+ if (!khugepaged_test_exit(mm))
+ collapse_and_free_pmd(mm, vma, addr, pmd);
mmap_write_unlock(mm);
} else {
/* Try again later */
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-debug_vm_pgtable-remove-pte-entry-from-the-page-table.patch
mm-page_table_check-use-unsigned-long-for-page-counters-and-cleanup.patch
mm-khugepaged-unify-collapse-pmd-clear-flush-and-free.patch
mm-page_table_check-check-entries-at-pmd-levels.patch
