mm: drop all references of writable and SCAN_PAGE_RO

Now that all actionable outcomes from checking pte_write() are gone, drop
the related references.

Link: https://lkml.kernel.org/r/20250908075028.38431-3-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Kiryl Shutsemau <kas@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
index 2305df6cb4853e9f33ff1791845ceee7c2e14d43..dd94d14a24272d942b66c053daf8ec94ba03dfb0 100644 (file)
--- a/include/trace/events/huge_memory.h
+++ b/include/trace/events/huge_memory.h
@@ -19,7 +19,6 @@
        EM( SCAN_PTE_NON_PRESENT,       "pte_non_present")              \
        EM( SCAN_PTE_UFFD_WP,           "pte_uffd_wp")                  \
        EM( SCAN_PTE_MAPPED_HUGEPAGE,   "pte_mapped_hugepage")          \
-       EM( SCAN_PAGE_RO,               "no_writable_page")             \
        EM( SCAN_LACK_REFERENCED_PAGE,  "lack_referenced_page")         \
        EM( SCAN_PAGE_NULL,             "page_null")                    \
        EM( SCAN_SCAN_ABORT,            "scan_aborted")                 \
@@ -55,15 +54,14 @@ SCAN_STATUS
 
 TRACE_EVENT(mm_khugepaged_scan_pmd,
 
-       TP_PROTO(struct mm_struct *mm, struct folio *folio, bool writable,
+       TP_PROTO(struct mm_struct *mm, struct folio *folio,
                 int referenced, int none_or_zero, int status, int unmapped),
 
-       TP_ARGS(mm, folio, writable, referenced, none_or_zero, status, unmapped),
+       TP_ARGS(mm, folio, referenced, none_or_zero, status, unmapped),
 
        TP_STRUCT__entry(
                __field(struct mm_struct *, mm)
                __field(unsigned long, pfn)
-               __field(bool, writable)
                __field(int, referenced)
                __field(int, none_or_zero)
                __field(int, status)
@@ -73,17 +71,15 @@ TRACE_EVENT(mm_khugepaged_scan_pmd,
        TP_fast_assign(
                __entry->mm = mm;
                __entry->pfn = folio ? folio_pfn(folio) : -1;
-               __entry->writable = writable;
                __entry->referenced = referenced;
                __entry->none_or_zero = none_or_zero;
                __entry->status = status;
                __entry->unmapped = unmapped;
        ),
 
-       TP_printk("mm=%p, scan_pfn=0x%lx, writable=%d, referenced=%d, none_or_zero=%d, status=%s, unmapped=%d",
+       TP_printk("mm=%p, scan_pfn=0x%lx, referenced=%d, none_or_zero=%d, status=%s, unmapped=%d",
                __entry->mm,
                __entry->pfn,
-               __entry->writable,
                __entry->referenced,
                __entry->none_or_zero,
                __print_symbolic(__entry->status, SCAN_STATUS),
@@ -117,15 +113,14 @@ TRACE_EVENT(mm_collapse_huge_page,
 TRACE_EVENT(mm_collapse_huge_page_isolate,
 
        TP_PROTO(struct folio *folio, int none_or_zero,
-                int referenced, bool  writable, int status),
+                int referenced, int status),
 
-       TP_ARGS(folio, none_or_zero, referenced, writable, status),
+       TP_ARGS(folio, none_or_zero, referenced, status),
 
        TP_STRUCT__entry(
                __field(unsigned long, pfn)
                __field(int, none_or_zero)
                __field(int, referenced)
-               __field(bool, writable)
                __field(int, status)
        ),
 
@@ -133,15 +128,13 @@ TRACE_EVENT(mm_collapse_huge_page_isolate,
                __entry->pfn = folio ? folio_pfn(folio) : -1;
                __entry->none_or_zero = none_or_zero;
                __entry->referenced = referenced;
-               __entry->writable = writable;
                __entry->status = status;
        ),
 
-       TP_printk("scan_pfn=0x%lx, none_or_zero=%d, referenced=%d, writable=%d, status=%s",
+       TP_printk("scan_pfn=0x%lx, none_or_zero=%d, referenced=%d, status=%s",
                __entry->pfn,
                __entry->none_or_zero,
                __entry->referenced,
-               __entry->writable,
                __print_symbolic(__entry->status, SCAN_STATUS))
 );
 

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a0f1df2a7ae644dfedcaa03ca513a954275d91ab..af5f5c80fe4ed3d9c61e7fbcd69d0103718a2057 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -39,7 +39,6 @@ enum scan_result {
        SCAN_PTE_NON_PRESENT,
        SCAN_PTE_UFFD_WP,
        SCAN_PTE_MAPPED_HUGEPAGE,
-       SCAN_PAGE_RO,
        SCAN_LACK_REFERENCED_PAGE,
        SCAN_PAGE_NULL,
        SCAN_SCAN_ABORT,
@@ -557,7 +556,6 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
        struct folio *folio = NULL;
        pte_t *_pte;
        int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0;
-       bool writable = false;
 
        for (_pte = pte; _pte < pte + HPAGE_PMD_NR;
             _pte++, address += PAGE_SIZE) {
@@ -671,9 +669,6 @@ next:
                     folio_test_referenced(folio) || mmu_notifier_test_young(vma->vm_mm,
                                                                     address)))
                        referenced++;
-
-               if (pte_write(pteval))
-                       writable = true;
        }
 
        if (unlikely(cc->is_khugepaged && !referenced)) {
@@ -681,13 +676,13 @@ next:
        } else {
                result = SCAN_SUCCEED;
                trace_mm_collapse_huge_page_isolate(folio, none_or_zero,
-                                                   referenced, writable, result);
+                                                   referenced, result);
                return result;
        }
 out:
        release_pte_pages(pte, _pte, compound_pagelist);
        trace_mm_collapse_huge_page_isolate(folio, none_or_zero,
-                                           referenced, writable, result);
+                                           referenced, result);
        return result;
 }
 
@@ -1280,7 +1275,6 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
        unsigned long _address;
        spinlock_t *ptl;
        int node = NUMA_NO_NODE, unmapped = 0;
-       bool writable = false;
 
        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 
@@ -1344,8 +1338,6 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
                        result = SCAN_PTE_UFFD_WP;
                        goto out_unmap;
                }
-               if (pte_write(pteval))
-                       writable = true;
 
                page = vm_normal_page(vma, _address, pteval);
                if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
@@ -1435,7 +1427,7 @@ out_unmap:
                *mmap_locked = false;
        }
 out:
-       trace_mm_khugepaged_scan_pmd(mm, folio, writable, referenced,
+       trace_mm_khugepaged_scan_pmd(mm, folio, referenced,
                                     none_or_zero, result, unmapped);
        return result;
 }