thp, mm: split_huge_page(): caller need to lock page

We're going to use migration entries instead of compound_lock() to
stabilize page refcounts.  Setup and remove migration entries require
page to be locked.

Some of split_huge_page() callers already have the page locked.  Let's
require everybody to lock the page before calling split_huge_page().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 13 insertions, 3 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5b965e27aaae..a2c987df80eb 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1149,7 +1149,9 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
         }
 
         if (!PageHuge(p) && PageTransHuge(hpage)) {
+                lock_page(hpage);
                 if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) {
+                        unlock_page(hpage);
                         if (!PageAnon(hpage))
                                 pr_err("MCE: %#lx: non anonymous thp\n", pfn);
                         else
@@ -1159,6 +1161,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
                         put_hwpoison_page(p);
                         return -EBUSY;
                 }
+                unlock_page(hpage);
                 VM_BUG_ON_PAGE(!page_count(p), p);
                 hpage = compound_head(p);
         }
@@ -1751,7 +1754,10 @@ int soft_offline_page(struct page *page, int flags)
                 return -EBUSY;
         }
         if (!PageHuge(page) && PageTransHuge(hpage)) {
-                if (PageAnon(hpage) && unlikely(split_huge_page(hpage))) {
+                lock_page(page);
+                ret = split_huge_page(hpage);
+                unlock_page(page);
+                if (unlikely(ret)) {
                         pr_info("soft offline: %#lx: failed to split THP\n",
                                 pfn);
                         if (flags & MF_COUNT_INCREASED)
diff --git a/mm/migrate.c b/mm/migrate.c
index 91545da23fd1..dec81a9e2fd6 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -943,9 +943,13 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
                 goto out;
         }
 
-        if (unlikely(PageTransHuge(page)))
-                if (unlikely(split_huge_page(page)))
+        if (unlikely(PageTransHuge(page))) {
+                lock_page(page);
+                rc = split_huge_page(page);
+                unlock_page(page);
+                if (rc)
                         goto out;
+        }
 
         rc = __unmap_and_move(page, newpage, force, mode);
         if (rc == MIGRATEPAGE_SUCCESS)