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Subject[PATCH] mm/sparse: fix memory leak of sparsemap_buf in aliged memory
Date
sparse_buffer_alloc(size) get size of memory from sparsemap_buf after
being aligned with the size. However, the size is at least
PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION) and usually larger
than PAGE_SIZE.
Also, the Sparse_buffer_fini() only frees memory between
sparsemap_buf and sparsemap_buf_end, since sparsemap_buf may be changed
by PTR_ALIGN() first, the aligned space before sparsemap_buf is
wasted and no one will touch it.

In our ARM32 platform (without SPARSEMEM_VMEMMAP)
Sparse_buffer_init
Reserve d359c000 - d3e9c000 (9M)
Sparse_buffer_alloc
Alloc d3a00000 - d3E80000 (4.5M)
Sparse_buffer_fini
Free d3e80000 - d3e9c000 (~=100k)
The reserved memory between d359c000 - d3a00000 (~=4.4M) is unfreed.

In ARM64 platform (with SPARSEMEM_VMEMMAP)

sparse_buffer_init
Reserve ffffffc07d623000 - ffffffc07f623000 (32M)
Sparse_buffer_alloc
Alloc ffffffc07d800000 - ffffffc07f600000 (30M)
Sparse_buffer_fini
Free ffffffc07f600000 - ffffffc07f623000 (140K)
The reserved memory between ffffffc07d623000 - ffffffc07d800000
(~=1.9M) is unfreed.

Let explicit free redundant aligned memory.

Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Mark-PK Tsai <Mark-PK.Tsai@mediatek.com>
Cc: YJ Chiang <yj.chiang@mediatek.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org
---
mm/sparse.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index fd13166949b5..2b3b5be85120 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -428,6 +428,12 @@ struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid,
static void *sparsemap_buf __meminitdata;
static void *sparsemap_buf_end __meminitdata;

+static inline void __init sparse_buffer_free(unsigned long size)
+{
+ WARN_ON(!sparsemap_buf || size == 0);
+ memblock_free_early(__pa(sparsemap_buf), size);
+}
+
static void __init sparse_buffer_init(unsigned long size, int nid)
{
phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
@@ -444,7 +450,7 @@ static void __init sparse_buffer_fini(void)
unsigned long size = sparsemap_buf_end - sparsemap_buf;

if (sparsemap_buf && size > 0)
- memblock_free_early(__pa(sparsemap_buf), size);
+ sparse_buffer_free(size);
sparsemap_buf = NULL;
}

@@ -456,8 +462,12 @@ void * __meminit sparse_buffer_alloc(unsigned long size)
ptr = PTR_ALIGN(sparsemap_buf, size);
if (ptr + size > sparsemap_buf_end)
ptr = NULL;
- else
+ else {
+ /* Free redundant aligned space */
+ if ((unsigned long)(ptr - sparsemap_buf) > 0)
+ sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
sparsemap_buf = ptr + size;
+ }
}
return ptr;
}
--
2.18.0
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