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>

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5b965e2..a2c987d 100644 (file)
--- 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 91545da..dec81a9 100644 (file)
--- 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)