[patch 107/262] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact[_nid]

Andrew Morton
2021-11-05T20:40:18Z

From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact[_nid]

Don't use with __GFP_HIGHMEM because page_address() cannot represent
highmem pages without kmap(). Newly allocated pages would leak as
page_address() will return NULL for highmem pages here. But It works now
because the callers do not specify __GFP_HIGHMEM now.

Link: https://lkml.kernel.org/r/20210902121242.41607-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/page_alloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/page_alloc.c~mm-page_allocc-avoid-allocating-highmem-pages-via-alloc_pages_exact
+++ a/mm/page_alloc.c
@@ -5610,8 +5610,8 @@ void *alloc_pages_exact(size_t size, gfp
unsigned int order = get_order(size);
unsigned long addr;

- if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
- gfp_mask &= ~__GFP_COMP;
+ if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
+ gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);

addr = __get_free_pages(gfp_mask, order);
return make_alloc_exact(addr, order, size);
@@ -5635,8 +5635,8 @@ void * __meminit alloc_pages_exact_nid(i
unsigned int order = get_order(size);
struct page *p;

- if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
- gfp_mask &= ~__GFP_COMP;
+ if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
+ gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);

p = alloc_pages_node(nid, gfp_mask, order);
if (!p)
_