From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: dan.j.williams@intel.com, akpm@linux-foundation.org,
Jan Kara <jack@suse.cz>
Cc: linux-nvdimm@lists.01.org, linux-mm@kvack.org,
linuxppc-dev@lists.ozlabs.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
stable@vger.kernel.org, Chandan Rajendra <chandan@linux.ibm.com>
Subject: [PATCH v2] mm: Fix modifying of page protection by insert_pfn_pmd()
Date: Tue, 2 Apr 2019 17:21:25 +0530 [thread overview]
Message-ID: <20190402115125.18803-1-aneesh.kumar@linux.ibm.com> (raw)
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>
---
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
next reply other threads:[~2019-04-02 11:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-02 11:51 Aneesh Kumar K.V [this message]
2019-04-02 15:24 ` [PATCH v2] mm: Fix modifying of page protection by insert_pfn_pmd() Jan Kara
2019-04-03 12:29 ` Sasha Levin
2019-04-09 4:46 ` Aneesh Kumar K.V
2019-04-24 17:13 ` Dan Williams
2019-04-24 17:38 ` Matthew Wilcox
2019-04-24 18:13 ` Dan Williams
2019-04-25 1:37 ` Aneesh Kumar K.V
2019-04-25 4:33 ` Dan Williams
2019-04-25 7:31 ` Jan Kara
2019-04-26 0:33 ` Dan Williams
2019-04-26 0:51 ` Matthew Wilcox
2019-04-26 8:36 ` Jan Kara
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