thp+memcg-numa: fix BUG at include/linux/mm.h:370!
THP's collapse_huge_page() has an understandable but ugly difference
in when its huge page is allocated: inside if NUMA but outside if not.
It's hardly surprising that the memcg failure path forgot that, freeing
the page in the non-NUMA case, then hitting a VM_BUG_ON in get_page()
(or even worse, using the freed page).
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index dbe99a5..113e35c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1762,6 +1762,10 @@
#ifndef CONFIG_NUMA
VM_BUG_ON(!*hpage);
new_page = *hpage;
+ if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
+ up_read(&mm->mmap_sem);
+ return;
+ }
#else
VM_BUG_ON(*hpage);
/*
@@ -1781,12 +1785,12 @@
*hpage = ERR_PTR(-ENOMEM);
return;
}
-#endif
if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
up_read(&mm->mmap_sem);
put_page(new_page);
return;
}
+#endif
/* after allocating the hugepage upgrade to mmap_sem write mode */
up_read(&mm->mmap_sem);