(2014/06/21 3:30), Toshi Kani wrote:
On Wed, 2014-06-18 at 15:38 +0900, Yasuaki Ishimatsu wrote:
  :
@@ -186,7 +186,12 @@ void sync_global_pgds(unsigned long start, unsigned long 
end)
                const pgd_t *pgd_ref = pgd_offset_k(address);
                struct page *page;

-               if (pgd_none(*pgd_ref))
+               /*
+                * When it is called after memory hot remove, pgd_none()
+                * returns true. In this case (removed == 1), we must clear
+                * the PGD entries in the local PGD level page.
+                */
+               if (pgd_none(*pgd_ref) && !removed)
                        continue;

                spin_lock(&pgd_lock);
@@ -199,12 +204,18 @@ void sync_global_pgds(unsigned long start, unsigned long 
end)
                        pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
                        spin_lock(pgt_lock);

-                       if (pgd_none(*pgd))
-                               set_pgd(pgd, *pgd_ref);
-                       else

+                       if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
                                BUG_ON(pgd_page_vaddr(*pgd)
                                       != pgd_page_vaddr(*pgd_ref));

+                       if (removed) {

Shouldn't this condition be "else if"?

The first if sentence checks whether PGDs hit to BUG_ON. And the second
if sentence checks whether the function was called after hot-removing memory.
I think that the first if sentence and the second if sentence check different
things. So I think the condition should be "if" sentence.

Thanks,
Yasuaki Ishimatsu


Thanks,
-Toshi

+                               if (pgd_none(*pgd_ref) && !pgd_none(*pgd))
+                                       pgd_clear(pgd);
+                       } else {
+                               if (pgd_none(*pgd))
+                                       set_pgd(pgd, *pgd_ref);
+                       }
+
                        spin_unlock(pgt_lock);
                }




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