On Tue 02-04-19 17:21:25, Aneesh Kumar K.V wrote:
With some architectures like ppc64, set_pmd_at() cannot cope with a situation where there is already some (different) valid entry present.
Use pmdp_set_access_flags() instead to modify the pfn which is built to deal with modifying existing PMD entries.
This is similar to commit cae85cb8add3 ("mm/memory.c: fix modifying of page protection by insert_pfn()")
We also do similar update w.r.t insert_pfn_pud eventhough ppc64 don't support pud pfn entries now.
Without this patch we also see the below message in kernel log "BUG: non-zero pgtables_bytes on freeing mm:"
CC: stable@vger.kernel.org Reported-by: Chandan Rajendra chandan@linux.ibm.com Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com
Looks good to me. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
Changes from v1:
- Fix the pgtable leak
mm/huge_memory.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 404acdcd0455..165ea46bf149 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -755,6 +755,21 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, spinlock_t *ptl; ptl = pmd_lock(mm, pmd);
- if (!pmd_none(*pmd)) {
if (write) {if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));goto out_unlock;}entry = pmd_mkyoung(*pmd);entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))update_mmu_cache_pmd(vma, addr, pmd);}goto out_unlock;- }
- entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); if (pfn_t_devmap(pfn)) entry = pmd_mkdevmap(entry);
@@ -766,11 +781,16 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, if (pgtable) { pgtable_trans_huge_deposit(mm, pmd, pgtable); mm_inc_nr_ptes(mm);
pgtable = NULL;set_pmd_at(mm, addr, pmd, entry); update_mmu_cache_pmd(vma, addr, pmd);
+out_unlock: spin_unlock(ptl);
- if (pgtable)
pte_free(mm, pgtable);} vm_fault_t vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, @@ -821,6 +841,20 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, spinlock_t *ptl; ptl = pud_lock(mm, pud);
- if (!pud_none(*pud)) {
if (write) {if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {WARN_ON_ONCE(!is_huge_zero_pud(*pud));goto out_unlock;}entry = pud_mkyoung(*pud);entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);if (pudp_set_access_flags(vma, addr, pud, entry, 1))update_mmu_cache_pud(vma, addr, pud);}goto out_unlock;- }
- entry = pud_mkhuge(pfn_t_pud(pfn, prot)); if (pfn_t_devmap(pfn)) entry = pud_mkdevmap(entry);
@@ -830,6 +864,8 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, } set_pud_at(mm, addr, pud, entry); update_mmu_cache_pud(vma, addr, pud);
+out_unlock: spin_unlock(ptl); } -- 2.20.1