[PATCH v2 11/26] mm: merge parameters for change_protection()

Peter Xu
2019-02-12T02:58:55Z

change_protection() was used by either the NUMA or mprotect() code,
there's one parameter for each of the callers (dirty_accountable and
prot_numa). Further, these parameters are passed along the calls:

- change_protection_range()
- change_p4d_range()
- change_pud_range()
- change_pmd_range()
- ...

Now we introduce a flag for change_protect() and all these helpers to
replace these parameters. Then we can avoid passing multiple parameters
multiple times along the way.

More importantly, it'll greatly simplify the work if we want to
introduce any new parameters to change_protection(). In the follow up
patches, a new parameter for userfaultfd write protection will be
introduced.

No functional change at all.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
include/linux/huge_mm.h | 2 +-
include/linux/mm.h | 14 +++++++++++++-
mm/huge_memory.c | 3 ++-
mm/mempolicy.c | 2 +-
mm/mprotect.c | 29 ++++++++++++++++-------------
5 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 381e872bfde0..1550fb12dbd4 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -46,7 +46,7 @@ extern bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
pmd_t *old_pmd, pmd_t *new_pmd);
extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, pgprot_t newprot,
- int prot_numa);
+ unsigned long cp_flags);
vm_fault_t vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, pfn_t pfn, bool write);
vm_fault_t vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 80bb6408fe73..9fe3b0066324 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1646,9 +1646,21 @@ extern unsigned long move_page_tables(struct vm_area_struct *vma,
unsigned long old_addr, struct vm_area_struct *new_vma,
unsigned long new_addr, unsigned long len,
bool need_rmap_locks);
+
+/*
+ * Flags used by change_protection(). For now we make it a bitmap so
+ * that we can pass in multiple flags just like parameters. However
+ * for now all the callers are only use one of the flags at the same
+ * time.
+ */
+/* Whether we should allow dirty bit accounting */
+#define MM_CP_DIRTY_ACCT (1UL << 0)
+/* Whether this protection change is for NUMA hints */
+#define MM_CP_PROT_NUMA (1UL << 1)
+
extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgprot_t newprot,
- int dirty_accountable, int prot_numa);
+ unsigned long cp_flags);
extern int mprotect_fixup(struct vm_area_struct *vma,
struct vm_area_struct **pprev, unsigned long start,
unsigned long end, unsigned long newflags);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index faf357eaf0ce..8d65b0f041f9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1860,13 +1860,14 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
* - HPAGE_PMD_NR is protections changed and TLB flush necessary
*/
int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, pgprot_t newprot, int prot_numa)
+ unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
{
struct mm_struct *mm = vma->vm_mm;
spinlock_t *ptl;
pmd_t entry;
bool preserve_write;
int ret;
+ bool prot_numa = cp_flags & MM_CP_PROT_NUMA;

ptl = __pmd_trans_huge_lock(pmd, vma);
if (!ptl)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d4496d9d34f5..233194f3d69a 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -554,7 +554,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
{
int nr_updated;

- nr_updated = change_protection(vma, addr, end, PAGE_NONE, 0, 1);
+ nr_updated = change_protection(vma, addr, end, PAGE_NONE, MM_CP_PROT_NUMA);
if (nr_updated)
count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated);

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 36cb358db170..a6ba448c8565 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -37,13 +37,15 @@

static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable, int prot_numa)
+ unsigned long cp_flags)
{
struct mm_struct *mm = vma->vm_mm;
pte_t *pte, oldpte;
spinlock_t *ptl;
unsigned long pages = 0;
int target_node = NUMA_NO_NODE;
+ bool dirty_accountable = cp_flags & MM_CP_DIRTY_ACCT;
+ bool prot_numa = cp_flags & MM_CP_PROT_NUMA;

/*
* Can be called with only the mmap_sem for reading by
@@ -164,7 +166,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,

static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
pud_t *pud, unsigned long addr, unsigned long end,
- pgprot_t newprot, int dirty_accountable, int prot_numa)
+ pgprot_t newprot, unsigned long cp_flags)
{
pmd_t *pmd;
unsigned long next;
@@ -194,7 +196,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
__split_huge_pmd(vma, pmd, addr, false, NULL);
} else {
int nr_ptes = change_huge_pmd(vma, pmd, addr,
- newprot, prot_numa);
+ newprot, cp_flags);

if (nr_ptes) {
if (nr_ptes == HPAGE_PMD_NR) {
@@ -209,7 +211,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
/* fall through, the trans huge pmd just split */
}
this_pages = change_pte_range(vma, pmd, addr, next, newprot,
- dirty_accountable, prot_numa);
+ cp_flags);
pages += this_pages;
next:
cond_resched();
@@ -225,7 +227,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,

static inline unsigned long change_pud_range(struct vm_area_struct *vma,
p4d_t *p4d, unsigned long addr, unsigned long end,
- pgprot_t newprot, int dirty_accountable, int prot_numa)
+ pgprot_t newprot, unsigned long cp_flags)
{
pud_t *pud;
unsigned long next;
@@ -237,7 +239,7 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma,
if (pud_none_or_clear_bad(pud))
continue;
pages += change_pmd_range(vma, pud, addr, next, newprot,
- dirty_accountable, prot_numa);
+ cp_flags);
} while (pud++, addr = next, addr != end);

return pages;
@@ -245,7 +247,7 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma,

static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
pgd_t *pgd, unsigned long addr, unsigned long end,
- pgprot_t newprot, int dirty_accountable, int prot_numa)
+ pgprot_t newprot, unsigned long cp_flags)
{
p4d_t *p4d;
unsigned long next;
@@ -257,7 +259,7 @@ static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
if (p4d_none_or_clear_bad(p4d))
continue;
pages += change_pud_range(vma, p4d, addr, next, newprot,
- dirty_accountable, prot_numa);
+ cp_flags);
} while (p4d++, addr = next, addr != end);

return pages;
@@ -265,7 +267,7 @@ static inline unsigned long change_p4d_range(struct vm_area_struct *vma,

static unsigned long change_protection_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable, int prot_numa)
+ unsigned long cp_flags)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
@@ -282,7 +284,7 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,
if (pgd_none_or_clear_bad(pgd))
continue;
pages += change_p4d_range(vma, pgd, addr, next, newprot,
- dirty_accountable, prot_numa);
+ cp_flags);
} while (pgd++, addr = next, addr != end);

/* Only flush the TLB if we actually modified any entries: */
@@ -295,14 +297,15 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,

unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgprot_t newprot,
- int dirty_accountable, int prot_numa)
+ unsigned long cp_flags)
{
unsigned long pages;

if (is_vm_hugetlb_page(vma))
pages = hugetlb_change_protection(vma, start, end, newprot);
else
- pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
+ pages = change_protection_range(vma, start, end, newprot,
+ cp_flags);

return pages;
}
@@ -430,7 +433,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
vma_set_page_prot(vma);

change_protection(vma, start, end, vma->vm_page_prot,
- dirty_accountable, 0);
+ dirty_accountable ? MM_CP_DIRTY_ACCT : 0);

/*
* Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
--
2.17.1