Re: [PATCH v3 07/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PTE modifying tests
From: Gavin Shan
Date: Thu Jul 22 2021 - 02:37:27 EST
Hi Anshuman,
On 7/22/21 3:56 PM, Anshuman Khandual wrote:
On 7/19/21 6:36 PM, Gavin Shan wrote:
This uses struct pgtable_debug_args in PTE modifying tests. The allocated
page is used as set_pte_at() is used there. The tests are skipped if
the allocated page doesn't exist. Besides, the unused variable @ptep
and @pte_aligned in debug_vm_pgtable() are dropped.
Please dont drop @ptep and @pte_aligned just yet.
We need to do so. Otherwise, there are build warning raised to
complain something like 'unused variable'.
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 75 ++++++++++++++++++++++---------------------
1 file changed, 39 insertions(+), 36 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index d32e55a95c55..eb6dda88e0d9 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -116,10 +116,7 @@ static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
WARN_ON(!pte_dirty(pte_wrprotect(pte_mkdirty(pte))));
}
-static void __init pte_advanced_tests(struct mm_struct *mm,
- struct vm_area_struct *vma, pte_t *ptep,
- unsigned long pfn, unsigned long vaddr,
- pgprot_t prot)
+static void __init pte_advanced_tests(struct pgtable_debug_args *args)
{
pte_t pte;
@@ -130,33 +127,38 @@ static void __init pte_advanced_tests(struct mm_struct *mm,
*/
pr_debug("Validating PTE advanced\n");
- pte = pfn_pte(pfn, prot);
- set_pte_at(mm, vaddr, ptep, pte);
- ptep_set_wrprotect(mm, vaddr, ptep);
- pte = ptep_get(ptep);
+ if (args->pte_pfn == ULONG_MAX) {
+ pr_debug("%s: Skipped\n", __func__);
+ return;
+ }
Just return. Please dont call out "Skipped". Also this check should be
performed before printing pr_debug("Validating PTE advanced\n"). The
print indicates that the test has started.
Sure.
+
+ pte = pfn_pte(args->pte_pfn, args->page_prot);
+ set_pte_at(args->mm, args->vaddr, args->ptep, pte);
+ ptep_set_wrprotect(args->mm, args->vaddr, args->ptep);
+ pte = ptep_get(args->ptep);
WARN_ON(pte_write(pte));
- ptep_get_and_clear(mm, vaddr, ptep);
- pte = ptep_get(ptep);
+ ptep_get_and_clear(args->mm, args->vaddr, args->ptep);
+ pte = ptep_get(args->ptep);
WARN_ON(!pte_none(pte));
- pte = pfn_pte(pfn, prot);
+ pte = pfn_pte(args->pte_pfn, args->page_prot);
pte = pte_wrprotect(pte);
pte = pte_mkclean(pte);
- set_pte_at(mm, vaddr, ptep, pte);
+ set_pte_at(args->mm, args->vaddr, args->ptep, pte);
pte = pte_mkwrite(pte);
pte = pte_mkdirty(pte);
- ptep_set_access_flags(vma, vaddr, ptep, pte, 1);
- pte = ptep_get(ptep);
+ ptep_set_access_flags(args->vma, args->vaddr, args->ptep, pte, 1);
+ pte = ptep_get(args->ptep);
WARN_ON(!(pte_write(pte) && pte_dirty(pte)));
- ptep_get_and_clear_full(mm, vaddr, ptep, 1);
- pte = ptep_get(ptep);
+ ptep_get_and_clear_full(args->mm, args->vaddr, args->ptep, 1);
+ pte = ptep_get(args->ptep);
WARN_ON(!pte_none(pte));
- pte = pfn_pte(pfn, prot);
+ pte = pfn_pte(args->pte_pfn, args->page_prot);
pte = pte_mkyoung(pte);
- set_pte_at(mm, vaddr, ptep, pte);
- ptep_test_and_clear_young(vma, vaddr, ptep);
- pte = ptep_get(ptep);
+ set_pte_at(args->mm, args->vaddr, args->ptep, pte);
+ ptep_test_and_clear_young(args->vma, args->vaddr, args->ptep);
+ pte = ptep_get(args->ptep);
WARN_ON(pte_young(pte));
}
@@ -617,20 +619,24 @@ static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
}
#endif /* PAGETABLE_P4D_FOLDED */
-static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
- unsigned long pfn, unsigned long vaddr,
- pgprot_t prot)
+static void __init pte_clear_tests(struct pgtable_debug_args *args)
{
- pte_t pte = pfn_pte(pfn, prot);
+ pte_t pte;
pr_debug("Validating PTE clear\n");
+ if (args->pte_pfn == ULONG_MAX) {
+ pr_debug("%s: Skipped\n", __func__);
+ return;
+ }
Just return. Please dont call out "Skipped". Also this check should be
performed before printing pr_debug("Validating PTE clear\n"). The print
indicates that the test has started.
Sure.
+
+ pte = pfn_pte(args->pte_pfn, args->page_prot);
Please keep this unchanged and move to its original position.
Ok.
#ifndef CONFIG_RISCV
pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
#endif
- set_pte_at(mm, vaddr, ptep, pte);
+ set_pte_at(args->mm, args->vaddr, args->ptep, pte);
barrier();
- pte_clear(mm, vaddr, ptep);
- pte = ptep_get(ptep);
+ pte_clear(args->mm, args->vaddr, args->ptep);
+ pte = ptep_get(args->ptep);
WARN_ON(!pte_none(pte));
}
@@ -1150,11 +1156,10 @@ static int __init debug_vm_pgtable(void)
p4d_t *p4dp, *saved_p4dp;
pud_t *pudp, *saved_pudp;
pmd_t *pmdp, *saved_pmdp, pmd;
- pte_t *ptep;
pgtable_t saved_ptep;
pgprot_t prot;
phys_addr_t paddr;
- unsigned long vaddr, pte_aligned, pmd_aligned;
+ unsigned long vaddr, pmd_aligned;
unsigned long pud_aligned;
spinlock_t *ptl = NULL;
int idx, ret;
@@ -1189,10 +1194,8 @@ static int __init debug_vm_pgtable(void)
*/
paddr = __pa_symbol(&start_kernel);
- pte_aligned = (paddr & PAGE_MASK) >> PAGE_SHIFT;
Please dont drop pte_aligned just yet.
We need to drop the variable. Otherwise, there is build warning to
complain: 'unused variable'.
pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
- WARN_ON(!pfn_valid(pte_aligned));
This should go into init_args() at the right place as the following,
after evaluating it from 'start_kernel' symbol - just to be sure.
WARN_ON(!pfn_valid(args->fixed_pte_pfn))
Yes.
pgdp = pgd_offset(mm, vaddr);
p4dp = p4d_alloc(mm, pgdp, vaddr);
@@ -1272,11 +1275,11 @@ static int __init debug_vm_pgtable(void)
* Page table modifying tests. They need to hold
* proper page table lock.
*/
-
- ptep = pte_offset_map_lock(mm, pmdp, vaddr, &ptl);
- pte_clear_tests(mm, ptep, pte_aligned, vaddr, prot);
- pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
- pte_unmap_unlock(ptep, ptl);
+ ptl = pte_lockptr(args.mm, args.pmdp);
+ spin_lock(ptl);
+ pte_clear_tests(&args);
+ pte_advanced_tests(&args);
+ spin_unlock(ptl);
Why pte_offset_map_lock()/pte_unmap_unlock() has been dropped and
spin_lock()/spin_unlock() sequence has been added ? Please dont
change the tests in these patches.
The semantics of pte_offset_map_lock() is to grab and take the lock
and return the PTE entry, which is mapped if needed. We already had
the PTE entry tracked by args->ptep in init_args(). So some of the
operations covered by pte_offset_map_lock() isn't needed any more.
ptl = pmd_lock(mm, pmdp);
pmd_clear_tests(mm, pmdp);
Thanks,
Gavin