mm, thp: move ptl taking inside page_check_address_pmd()
With split page table lock we can't know which lock we need to take
before we find the relevant pmd.
Let's move lock taking inside the function.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Alex Thorlton <athorlton@sgi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 471eb04..c2082ab 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1552,23 +1552,33 @@
return 0;
}
+/*
+ * This function returns whether a given @page is mapped onto the @address
+ * in the virtual space of @mm.
+ *
+ * When it's true, this function returns *pmd with holding the page table lock
+ * and passing it back to the caller via @ptl.
+ * If it's false, returns NULL without holding the page table lock.
+ */
pmd_t *page_check_address_pmd(struct page *page,
struct mm_struct *mm,
unsigned long address,
- enum page_check_address_pmd_flag flag)
+ enum page_check_address_pmd_flag flag,
+ spinlock_t **ptl)
{
- pmd_t *pmd, *ret = NULL;
+ pmd_t *pmd;
if (address & ~HPAGE_PMD_MASK)
- goto out;
+ return NULL;
pmd = mm_find_pmd(mm, address);
if (!pmd)
- goto out;
+ return NULL;
+ *ptl = pmd_lock(mm, pmd);
if (pmd_none(*pmd))
- goto out;
+ goto unlock;
if (pmd_page(*pmd) != page)
- goto out;
+ goto unlock;
/*
* split_vma() may create temporary aliased mappings. There is
* no risk as long as all huge pmd are found and have their
@@ -1578,14 +1588,15 @@
*/
if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
pmd_trans_splitting(*pmd))
- goto out;
+ goto unlock;
if (pmd_trans_huge(*pmd)) {
VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
!pmd_trans_splitting(*pmd));
- ret = pmd;
+ return pmd;
}
-out:
- return ret;
+unlock:
+ spin_unlock(*ptl);
+ return NULL;
}
static int __split_huge_page_splitting(struct page *page,
@@ -1593,6 +1604,7 @@
unsigned long address)
{
struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
pmd_t *pmd;
int ret = 0;
/* For mmu_notifiers */
@@ -1600,9 +1612,8 @@
const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
- spin_lock(&mm->page_table_lock);
pmd = page_check_address_pmd(page, mm, address,
- PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
+ PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
if (pmd) {
/*
* We can't temporarily set the pmd to null in order
@@ -1613,8 +1624,8 @@
*/
pmdp_splitting_flush(vma, address, pmd);
ret = 1;
+ spin_unlock(ptl);
}
- spin_unlock(&mm->page_table_lock);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
return ret;
@@ -1745,14 +1756,14 @@
unsigned long address)
{
struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
pmd_t *pmd, _pmd;
int ret = 0, i;
pgtable_t pgtable;
unsigned long haddr;
- spin_lock(&mm->page_table_lock);
pmd = page_check_address_pmd(page, mm, address,
- PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
+ PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
if (pmd) {
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
pmd_populate(mm, &_pmd, pgtable);
@@ -1807,8 +1818,8 @@
pmdp_invalidate(vma, address, pmd);
pmd_populate(mm, pmd, pgtable);
ret = 1;
+ spin_unlock(ptl);
}
- spin_unlock(&mm->page_table_lock);
return ret;
}