Hi Anshuman,

On 7/22/21 5:11 PM, Anshuman Khandual wrote:

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On 7/22/21 12:11 PM, Gavin Shan wrote:

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On 7/22/21 3:45 PM, Anshuman Khandual wrote:

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On 7/19/21 6:36 PM, Gavin Shan wrote:

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This uses struct pgtable_debug_args in PMD modifying tests. The allocated
huge page is used when set_pmd_at() is used. The corresponding tests
are skipped if the huge page doesn't exist. Besides, the unused variable
@pmd_aligned in debug_vm_pgtable() is dropped.

Please dont drop @pmd_aligned just yet.

We need do so. Otherwise, there is build warning to complain
something like 'unused variable' after this patch is applied.

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Signed-off-by: Gavin Shan <redacted>
---
   mm/debug_vm_pgtable.c | 102 ++++++++++++++++++++----------------------
   1 file changed, 48 insertions(+), 54 deletions(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index eb6dda88e0d9..cec3cbf99a6b 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c

@@ -213,54 +213,54 @@ static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)

       WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
   }
   -static void __init pmd_advanced_tests(struct mm_struct *mm,
-                      struct vm_area_struct *vma, pmd_t *pmdp,
-                      unsigned long pfn, unsigned long vaddr,
-                      pgprot_t prot, pgtable_t pgtable)
+static void __init pmd_advanced_tests(struct pgtable_debug_args *args)
   {
       pmd_t pmd;
+    unsigned long vaddr = (args->vaddr & HPAGE_PMD_MASK);
         if (!has_transparent_hugepage())
           return;
         pr_debug("Validating PMD advanced\n");
-    /* Align the address wrt HPAGE_PMD_SIZE */
-    vaddr &= HPAGE_PMD_MASK;

Please just leave these unchanged. If has_transparent_hugepage() evaluates
negative, it skips the masking operation. As mentioned earlier please avoid
changing the test in any manner during these transition patches.

Ok.

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+    if (args->pmd_pfn == ULONG_MAX) {
+        pr_debug("%s: Skipped\n", __func__);
+        return;
+    }

Just return. Please dont call out "Skipped".

Ok.

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quoted

   -    pgtable_trans_huge_deposit(mm, pmdp, pgtable);
+    pgtable_trans_huge_deposit(args->mm, args->pmdp, args->start_ptep);
   -    pmd = pfn_pmd(pfn, prot);
-    set_pmd_at(mm, vaddr, pmdp, pmd);
-    pmdp_set_wrprotect(mm, vaddr, pmdp);
-    pmd = READ_ONCE(*pmdp);
+    pmd = pfn_pmd(args->pmd_pfn, args->page_prot);
+    set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
+    pmdp_set_wrprotect(args->mm, vaddr, args->pmdp);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(pmd_write(pmd));
-    pmdp_huge_get_and_clear(mm, vaddr, pmdp);
-    pmd = READ_ONCE(*pmdp);
+    pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(!pmd_none(pmd));
   -    pmd = pfn_pmd(pfn, prot);
+    pmd = pfn_pmd(args->pmd_pfn, args->page_prot);
       pmd = pmd_wrprotect(pmd);
       pmd = pmd_mkclean(pmd);
-    set_pmd_at(mm, vaddr, pmdp, pmd);
+    set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
       pmd = pmd_mkwrite(pmd);
       pmd = pmd_mkdirty(pmd);
-    pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1);
-    pmd = READ_ONCE(*pmdp);
+    pmdp_set_access_flags(args->vma, vaddr, args->pmdp, pmd, 1);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
-    pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1);
-    pmd = READ_ONCE(*pmdp);
+    pmdp_huge_get_and_clear_full(args->vma, vaddr, args->pmdp, 1);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(!pmd_none(pmd));
   -    pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
+    pmd = pmd_mkhuge(pfn_pmd(args->pmd_pfn, args->page_prot));
       pmd = pmd_mkyoung(pmd);
-    set_pmd_at(mm, vaddr, pmdp, pmd);
-    pmdp_test_and_clear_young(vma, vaddr, pmdp);
-    pmd = READ_ONCE(*pmdp);
+    set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
+    pmdp_test_and_clear_young(args->vma, vaddr, args->pmdp);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(pmd_young(pmd));
         /*  Clear the pte entries  */
-    pmdp_huge_get_and_clear(mm, vaddr, pmdp);
-    pgtable = pgtable_trans_huge_withdraw(mm, pmdp);
+    pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp);
+    pgtable_trans_huge_withdraw(args->mm, args->pmdp);
   }
     static void __init pmd_leaf_tests(struct pgtable_debug_args *args)

@@ -417,12 +417,7 @@ static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }

   #else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
   static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx) { }
   static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
-static void __init pmd_advanced_tests(struct mm_struct *mm,
-                      struct vm_area_struct *vma, pmd_t *pmdp,
-                      unsigned long pfn, unsigned long vaddr,
-                      pgprot_t prot, pgtable_t pgtable)
-{
-}
+static void __init pmd_advanced_tests(struct pgtable_debug_args *args) { }
   static void __init pud_advanced_tests(struct mm_struct *mm,
                         struct vm_area_struct *vma, pud_t *pudp,
                         unsigned long pfn, unsigned long vaddr,

@@ -435,11 +430,11 @@ static void __init pmd_savedwrite_tests(struct pgtable_debug_args *args) { }

   #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
     #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
-static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
+static void __init pmd_huge_tests(struct pgtable_debug_args *args)
   {
       pmd_t pmd;
   -    if (!arch_vmap_pmd_supported(prot))
+    if (!arch_vmap_pmd_supported(args->page_prot))
           return;
         pr_debug("Validating PMD huge\n");

@@ -447,10 +442,11 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)

        * X86 defined pmd_set_huge() verifies that the given
        * PMD is not a populated non-leaf entry.
        */
-    WRITE_ONCE(*pmdp, __pmd(0));
-    WARN_ON(!pmd_set_huge(pmdp, __pfn_to_phys(pfn), prot));
-    WARN_ON(!pmd_clear_huge(pmdp));
-    pmd = READ_ONCE(*pmdp);
+    WRITE_ONCE(*(args->pmdp), __pmd(0));

Possible extra braces.

Will drop it in v4, thanks!

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+    WARN_ON(!pmd_set_huge(args->pmdp, __pfn_to_phys(args->fixed_pmd_pfn),
+                  args->page_prot));

Dont break the line.

Ok.

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+    WARN_ON(!pmd_clear_huge(args->pmdp));
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(!pmd_none(pmd));
   }
   @@ -473,7 +469,7 @@ static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
       WARN_ON(!pud_none(pud));
   }
   #else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
-static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot) { }
+static void __init pmd_huge_tests(struct pgtable_debug_args *args) { }
   static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot) { }
   #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
   @@ -640,20 +636,19 @@ static void __init pte_clear_tests(struct pgtable_debug_args *args)
       WARN_ON(!pte_none(pte));
   }
   -static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp)
+static void __init pmd_clear_tests(struct pgtable_debug_args *args)
   {
-    pmd_t pmd = READ_ONCE(*pmdp);
+    pmd_t pmd = READ_ONCE(*(args->pmdp));
         pr_debug("Validating PMD clear\n");
       pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE);
-    WRITE_ONCE(*pmdp, pmd);
-    pmd_clear(pmdp);
-    pmd = READ_ONCE(*pmdp);
+    WRITE_ONCE(*(args->pmdp), pmd);
+    pmd_clear(args->pmdp);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(!pmd_none(pmd));
   }
   -static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
-                      pgtable_t pgtable)
+static void __init pmd_populate_tests(struct pgtable_debug_args *args)
   {
       pmd_t pmd;
   @@ -662,8 +657,8 @@ static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
        * This entry points to next level page table page.
        * Hence this must not qualify as pmd_bad().
        */
-    pmd_populate(mm, pmdp, pgtable);
-    pmd = READ_ONCE(*pmdp);
+    pmd_populate(args->mm, args->pmdp, args->start_ptep);
+    pmd = READ_ONCE(*(args->pmdp));
       WARN_ON(pmd_bad(pmd));
   }
   @@ -1159,7 +1154,7 @@ static int __init debug_vm_pgtable(void)
       pgtable_t saved_ptep;
       pgprot_t prot;
       phys_addr_t paddr;
-    unsigned long vaddr, pmd_aligned;
+    unsigned long vaddr;
       unsigned long pud_aligned;
       spinlock_t *ptl = NULL;
       int idx, ret;

@@ -1194,7 +1189,6 @@ static int __init debug_vm_pgtable(void)

        */
       paddr = __pa_symbol(&start_kernel);
   -    pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;

Please dont drop these just yet and wait until [PATCH 11/12].

Otherwise, it causes build warning: 'unused variable'.

Why ? Just the evaluation of 'pmd_aligned' from 'paddr' should
be enough to avoid such warning. 'pmd_aligned' need not be used
afterwards.

It's not enough to avoid the warning. I apply the patches till
this one (PATCH[v3 08/12]) and have additional code to keep
@pmd_aligned, then I run into build warning as below:

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index cec3cbf99a6b..961c9bb6fc7c 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c

@@ -1154,7 +1154,7 @@ static int __init debug_vm_pgtable(void)

        pgtable_t saved_ptep;
        pgprot_t prot;
        phys_addr_t paddr;
-       unsigned long vaddr;
+       unsigned long vaddr, pmd_aligned;
        unsigned long pud_aligned;
        spinlock_t *ptl = NULL;
        int idx, ret;

@@ -1189,6 +1189,7 @@ static int __init debug_vm_pgtable(void)

         */
        paddr = __pa_symbol(&start_kernel);
 
+       pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
        pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
 
        pgdp = pgd_offset(mm, vaddr);

[gwshan@gshan l]$ make W=1 mm/debug_vm_pgtable.o
     :
mm/debug_vm_pgtable.c: In function ‘debug_vm_pgtable’:
mm/debug_vm_pgtable.c:1157:23: warning: variable ‘pmd_aligned’ set but not used [-Wunused-but-set-variable]
 1157 |  unsigned long vaddr, pmd_aligned;
      |                       ^~~~~~~~~~~


By the way, 0-day is trying to build kernel with "W=1". It means the
build warnings will be reported by 0-day if the unused variables aren't
dropped from individual patches. It makes the review a bit harder. However,