mm, thp: change pmd_trans_huge_lock() to return taken lock

With split ptlock it's important to know which lock
pmd_trans_huge_lock() took.  This patch adds one more parameter to the
function to return the lock.

In most places migration to new api is trivial.  Exception is
move_huge_pmd(): we need to take two locks if pmd tables are different.

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>

1 files changed, 7 insertions, 6 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8faaebdc6b02..42b5cf5d0326 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -506,9 +506,9 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
         pte_t *pte;
         spinlock_t *ptl;
 
-        if (pmd_trans_huge_lock(pmd, vma) == 1) {
+        if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
                 smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk);
-                spin_unlock(&walk->mm->page_table_lock);
+                spin_unlock(ptl);
                 mss->anonymous_thp += HPAGE_PMD_SIZE;
                 return 0;
         }
@@ -999,13 +999,14 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 {
         struct vm_area_struct *vma;
         struct pagemapread *pm = walk->private;
+        spinlock_t *ptl;
         pte_t *pte;
         int err = 0;
         pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
 
         /* find the first VMA at or above 'addr' */
         vma = find_vma(walk->mm, addr);
-        if (vma && pmd_trans_huge_lock(pmd, vma) == 1) {
+        if (vma && pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
                 int pmd_flags2;
 
                 if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
@@ -1023,7 +1024,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                         if (err)
                                 break;
                 }
-                spin_unlock(&walk->mm->page_table_lock);
+                spin_unlock(ptl);
                 return err;
         }
 
@@ -1325,7 +1326,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
 
         md = walk->private;
 
-        if (pmd_trans_huge_lock(pmd, md->vma) == 1) {
+        if (pmd_trans_huge_lock(pmd, md->vma, &ptl) == 1) {
                 pte_t huge_pte = *(pte_t *)pmd;
                 struct page *page;
 
@@ -1333,7 +1334,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
                 if (page)
                         gather_stats(page, md, pte_dirty(huge_pte),
                                      HPAGE_PMD_SIZE/PAGE_SIZE);
-                spin_unlock(&walk->mm->page_table_lock);
+                spin_unlock(ptl);
                 return 0;
         }