Re: [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PMD modifying tests
From: Gavin Shan
Date: Thu Jul 22 2021 - 21:00:12 EST
Hi Anshuman,
On 7/22/21 5:11 PM, Anshuman Khandual wrote:
On 7/22/21 12:11 PM, Gavin Shan wrote:
On 7/22/21 3:45 PM, Anshuman Khandual wrote:
On 7/19/21 6:36 PM, Gavin Shan wrote:
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.
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
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.
+ if (args->pmd_pfn == ULONG_MAX) {
+ pr_debug("%s: Skipped\n", __func__);
+ return;
+ }
Just return. Please dont call out "Skipped".
Ok.
- 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!
+ WARN_ON(!pmd_set_huge(args->pmdp, __pfn_to_phys(args->fixed_pmd_pfn),
+ args->page_prot));
Dont break the line.
Ok.
+ 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,
we still need to keep each individual patch complete to make 'git bisect'
friendly.
Thanks,
Gavin