Commit 2bc5bab9 authored by Yaliang Wang's avatar Yaliang Wang Committed by Thomas Bogendoerfer
Browse files

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



pgd page is freed by generic implementation pgd_free() since commit
f9cb654c ("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: f9cb654c ("asm-generic: pgalloc: provide generic pgd_free()")
Signed-off-by: default avatarYaliang Wang <Yaliang.Wang@windriver.com>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
parent 8755d57b

arch/mips/include/asm/pgalloc.h

+6 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 


#define __HAVE_ARCH_PMD_ALLOC_ONE

#define __HAVE_ARCH_PUD_ALLOC_ONE

#define __HAVE_ARCH_PGD_FREE

#include <asm-generic/pgalloc.h>



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 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)			\

do {							\

	pgtable_pte_page_dtor(pte);			\