mm/huge_memory: add and use has_deposited_pgtable()

Rather than thread has_deposited through zap_huge_pmd(), make things
clearer by adding has_deposited_pgtable() with comments describing why in
each case.

[ljs@kernel.org: fix folio_put()-before-recheck issue, per Sashiko]
Link: https://lkml.kernel.org/r/0a917f80-902f-49b0-a75f-1bbaf23d7f94@lucifer.local
Link: https://lkml.kernel.org/r/f9db59ca90937e39913d50ecb4f662e2bad17bbb.1774029655.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ade49830c699588673291aed86b49b6f613f681b..745eb3d0d4a7867ece9e0d31879a17119f17e9b9 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2403,8 +2403,7 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
 }
 
 static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma,
-               pmd_t pmdval, struct folio *folio, bool is_present,
-               bool *has_deposit)
+               pmd_t pmdval, struct folio *folio, bool is_present)
 {
        const bool is_device_private = folio_is_device_private(folio);
 
@@ -2413,7 +2412,6 @@ static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma,
                folio_remove_rmap_pmd(folio, &folio->page, vma);
 
        if (folio_test_anon(folio)) {
-               *has_deposit = true;
                add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
        } else {
                add_mm_counter(mm, mm_counter_file(folio),
@@ -2440,6 +2438,27 @@ static struct folio *normal_or_softleaf_folio_pmd(struct vm_area_struct *vma,
        return pmd_to_softleaf_folio(pmdval);
 }
 
+static bool has_deposited_pgtable(struct vm_area_struct *vma, pmd_t pmdval,
+               struct folio *folio)
+{
+       /* Some architectures require unconditional depositing. */
+       if (arch_needs_pgtable_deposit())
+               return true;
+
+       /*
+        * Huge zero always deposited except for DAX which handles itself, see
+        * set_huge_zero_folio().
+        */
+       if (is_huge_zero_pmd(pmdval))
+               return !vma_is_dax(vma);
+
+       /*
+        * Otherwise, only anonymous folios are deposited, see
+        * __do_huge_pmd_anonymous_page().
+        */
+       return folio && folio_test_anon(folio);
+}
+
 /**
  * zap_huge_pmd - Zap a huge THP which is of PMD size.
  * @tlb: The MMU gather TLB state associated with the operation.
@@ -2452,10 +2471,10 @@ static struct folio *normal_or_softleaf_folio_pmd(struct vm_area_struct *vma,
 bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                 pmd_t *pmd, unsigned long addr)
 {
-       bool has_deposit = arch_needs_pgtable_deposit();
        struct mm_struct *mm = tlb->mm;
        struct folio *folio = NULL;
        bool is_present = false;
+       bool has_deposit;
        spinlock_t *ptl;
        pmd_t orig_pmd;
 
@@ -2477,12 +2496,9 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 
        is_present = pmd_present(orig_pmd);
        folio = normal_or_softleaf_folio_pmd(vma, addr, orig_pmd, is_present);
+       has_deposit = has_deposited_pgtable(vma, orig_pmd, folio);
        if (folio)
-               zap_huge_pmd_folio(mm, vma, orig_pmd, folio, is_present,
-                                  &has_deposit);
-       else if (is_huge_zero_pmd(orig_pmd))
-               has_deposit = has_deposit || !vma_is_dax(vma);
-
+               zap_huge_pmd_folio(mm, vma, orig_pmd, folio, is_present);
        if (has_deposit)
                zap_deposited_table(mm, pmd);