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MIPS: pgalloc: fix memory leak caused by pgd_free()

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pgd page is freed by generic implementation pgd_free() since commit
f9cb654cb5 ("asm-generic: pgalloc: provide generic pgd_free()"),
however, there are scenarios that the system uses more than one page as
the pgd table, in such cases the generic implementation pgd_free() won't
be applicable anymore. For example, when PAGE_SIZE_4KB is enabled and
MIPS_VA_BITS_48 is not enabled in a 64bit system, the macro "PGD_ORDER"
will be set as "1", which will cause allocating two pages as the pgd
table. Well, at the same time, the generic implementation pgd_free()
just free one pgd page, which will result in the memory leak.

The memory leak can be easily detected by executing shell command:
"while true; do ls > /dev/null; grep MemFree /proc/meminfo; done"

Fixes: f9cb654cb5 ("asm-generic: pgalloc: provide generic pgd_free()")
Signed-off-by: Yaliang Wang <Yaliang.Wang@windriver.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Yaliang Wang 2022-03-10 19:31:16 +08:00 committed by Thomas Bogendoerfer
parent 8755d57ba1
commit 2bc5bab9a7
1 changed files with 6 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

6
arch/mips/include/asm/pgalloc.h
View file

@ -15,6 +15,7 @@
#define __HAVE_ARCH_PMD_ALLOC_ONE #define __HAVE_ARCH_PMD_ALLOC_ONE
#define __HAVE_ARCH_PUD_ALLOC_ONE #define __HAVE_ARCH_PUD_ALLOC_ONE
#define __HAVE_ARCH_PGD_FREE
#include <asm-generic/pgalloc.h> #include <asm-generic/pgalloc.h>
static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
@ -48,6 +49,11 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
extern void pgd_init(unsigned long page); extern void pgd_init(unsigned long page);
extern pgd_t *pgd_alloc(struct mm_struct *mm); extern pgd_t *pgd_alloc(struct mm_struct *mm);
static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
free_pages((unsigned long)pgd, PGD_ORDER);
}
#define __pte_free_tlb(tlb,pte,address) \ #define __pte_free_tlb(tlb,pte,address) \
do { \ do { \
pgtable_pte_page_dtor(pte); \ pgtable_pte_page_dtor(pte); \