mm: __first_valid_page skip over offline pages

__first_valid_page skips over invalid pfns in the range but it might
still stumble over offline pages.  At least start_isolate_page_range
will mark those set_migratetype_isolate.  This doesn't represent any
immediate AFAICS because alloc_contig_range will fail to isolate those
pages but it relies on not fully initialized page which will become a
problem later when we stop associating offline pages to zones.  Use
pfn_to_online_page to handle this.

This is more a preparatory patch than a fix.

Link: http://lkml.kernel.org/r/20170515085827.16474-10-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 5092e4ef00c832fefb624a1d9d8f618402ad4402..3606104893e0b8dce843d5ac8fcf3f48434ab5f9 100644 (file)
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -138,12 +138,18 @@ static inline struct page *
 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 {
        int i;
-       for (i = 0; i < nr_pages; i++)
-               if (pfn_valid_within(pfn + i))
-                       break;
-       if (unlikely(i == nr_pages))
-               return NULL;
-       return pfn_to_page(pfn + i);
+
+       for (i = 0; i < nr_pages; i++) {
+               struct page *page;
+
+               if (!pfn_valid_within(pfn + i))
+                       continue;
+               page = pfn_to_online_page(pfn + i);
+               if (!page)
+                       continue;
+               return page;
+       }
+       return NULL;
 }
 
 /*
@@ -184,8 +190,12 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 undo:
        for (pfn = start_pfn;
             pfn < undo_pfn;
-            pfn += pageblock_nr_pages)
-               unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
+            pfn += pageblock_nr_pages) {
+               struct page *page = pfn_to_online_page(pfn);
+               if (!page)
+                       continue;
+               unset_migratetype_isolate(page, migratetype);
+       }
 
        return -EBUSY;
 }