On 9/1/20 8:55 AM, Anshuman Khandual wrote:
On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote:
pte_clear_tests operate on an existing pte entry. Make sure that is not a none
pte entry.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 21329c7d672f..8527ebb75f2c 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -546,7 +546,7 @@ static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
unsigned long vaddr)
{
- pte_t pte = ptep_get(ptep);
+ pte_t pte = ptep_get_and_clear(mm, vaddr, ptep);
Seems like ptep_get_and_clear() here just clears the entry in preparation
for a following set_pte_at() which otherwise would have been a problem on
ppc64 as you had pointed out earlier i.e set_pte_at() should not update an
existing valid entry. So the commit message here is bit misleading.
and also fetch the pte value which is used further.
pr_debug("Validating PTE clear\n");
pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
@@ -944,7 +944,7 @@ 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;
+ pte_t *ptep, pte;
pgtable_t saved_ptep;
pgprot_t prot, protnone;
phys_addr_t paddr;
@@ -1049,6 +1049,8 @@ static int __init debug_vm_pgtable(void)
*/
ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl);
+ pte = pfn_pte(pte_aligned, prot);
+ set_pte_at(mm, vaddr, ptep, pte);
Not here, creating and populating an entry must be done in respective
test functions itself. Besides, this seems bit redundant as well. The
test pte_clear_tests() with the above change added, already
- Clears the PTEP entry with ptep_get_and_clear()
and fetch the old value set previously.
- Creates and populates the PTEP with set_pte_at()
- Clears with pte_clear()
- Checks for pte_none()
If the objective is to clear the PTEP entry before calling set_pte_at(),
then only the first chunk is required and it should also be merged with
a previous patch.
[PATCH v3 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry
pte_clear_tests(mm, ptep, vaddr);
pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
pte_unmap_unlock(ptep, ptl);
There is a checkpatch.pl warning here.
WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#7:
pte_clear_tests operate on an existing pte entry. Make sure that is not a none
total: 0 errors, 1 warnings, 24 lines checked
There is also a build failure on x86 reported from kernel test robot.
