1 From 7f297c70bebd20f3e02c9b6046e4e5e71d38ffe9 Mon Sep 17 00:00:00 2001
2 From: Yaliang Wang <Yaliang.Wang@windriver.com>
3 Date: Thu, 10 Mar 2022 19:31:16 +0800
4 Subject: [PATCH] MIPS: pgalloc: fix memory leak caused by pgd_free()
6 pgd page is freed by generic implementation pgd_free() since commit
7 f9cb654cb550 ("asm-generic: pgalloc: provide generic pgd_free()"),
8 however, there are scenarios that the system uses more than one page as
9 the pgd table, in such cases the generic implementation pgd_free() won't
10 be applicable anymore. For example, when PAGE_SIZE_4KB is enabled and
11 MIPS_VA_BITS_48 is not enabled in a 64bit system, the macro "PGD_ORDER"
12 will be set as "1", which will cause allocating two pages as the pgd
13 table. Well, at the same time, the generic implementation pgd_free()
14 just free one pgd page, which will result in the memory leak.
16 The memory leak can be easily detected by executing shell command:
17 "while true; do ls > /dev/null; grep MemFree /proc/meminfo; done"
19 Fixes: f9cb654cb550 ("asm-generic: pgalloc: provide generic pgd_free()")
20 Signed-off-by: Yaliang Wang <Yaliang.Wang@windriver.com>
21 Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
22 (cherry picked from commit 2bc5bab9a763d520937e4f3fe8df51c6a1eceb97)
24 arch/mips/include/asm/pgalloc.h | 6 ++++++
25 1 file changed, 6 insertions(+)
27 --- a/arch/mips/include/asm/pgalloc.h
28 +++ b/arch/mips/include/asm/pgalloc.h
31 #define __HAVE_ARCH_PMD_ALLOC_ONE
32 #define __HAVE_ARCH_PUD_ALLOC_ONE
33 +#define __HAVE_ARCH_PGD_FREE
34 #include <asm-generic/pgalloc.h>
36 static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
37 @@ -48,6 +49,11 @@ static inline void pud_populate(struct m
38 extern void pgd_init(unsigned long page);
39 extern pgd_t *pgd_alloc(struct mm_struct *mm);
41 +static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
43 + free_pages((unsigned long)pgd, PGD_ORDER);
46 #define __pte_free_tlb(tlb,pte,address) \
48 pgtable_pte_page_dtor(pte); \