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Subject[PATCH v1] mm:free unused pages in kmalloc_order
Environment using the slub allocator, 1G memory in my ARM32.
kmalloc(1024, GFP_HIGHUSER) can allocate memory normally,
kmalloc(64*1024, GFP_HIGHUSER) will cause a memory leak, because
alloc_pages returns highmem physical pages, but it cannot be directly
converted into a virtual address and return NULL, the pages has not
been released. Usually driver developers will not use the
GFP_HIGHUSER flag to allocate memory in kmalloc, but I think this
memory leak is not perfect, it is best to be fixed. This is the
first time I have posted a patch, there may be something wrong.

Signed-off-by: Long Li <lonuxli.64@gmail.com>
---
mm/slab_common.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index a143a8c8f874..d2c53b980ab3 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -819,8 +819,12 @@ void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
page = alloc_pages(flags, order);
if (likely(page)) {
ret = page_address(page);
- mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
- PAGE_SIZE << order);
+ if (ret)
+ mod_node_page_state(page_pgdat(page),
+ NR_SLAB_UNRECLAIMABLE_B,
+ PAGE_SIZE << order);
+ else
+ __free_pages(page, order);
}
ret = kasan_kmalloc_large(ret, size, flags);
/* As ret might get tagged, call kmemleak hook after KASAN. */
--
2.17.1
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