On 14/03/18 08:48, Chintan Pandya wrote: > While setting huge page, we need to take care of > previously existing next level mapping. Since, > we are going to overrite previous mapping, the > only reference to next level page table will get > lost and the next level page table will be zombie, > occupying space forever. So, free it before > overriding. > > Signed-off-by: Chintan Pandya <cpandya@xxxxxxxxxxxxxx> > --- > arch/arm64/mm/mmu.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 8c704f1..c0df264 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -32,7 +32,7 @@ > #include <linux/io.h> > #include <linux/mm.h> > #include <linux/vmalloc.h> > - > +#include <linux/hugetlb.h> > #include <asm/barrier.h> > #include <asm/cputype.h> > #include <asm/fixmap.h> > @@ -45,6 +45,7 @@ > #include <asm/memblock.h> > #include <asm/mmu_context.h> > #include <asm/ptdump.h> > +#include <asm/page.h> > > #define NO_BLOCK_MAPPINGS BIT(0) > #define NO_CONT_MAPPINGS BIT(1) > @@ -939,6 +940,9 @@ int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot) > return 0; > > BUG_ON(phys & ~PUD_MASK); > + if (pud_val(*pud) && !pud_huge(*pud)) > + free_page((unsigned long)__va(pud_val(*pud))); > + This is absolutely scary. Isn't this page still referenced in the page tables (assuming patch 4 has been applied too)? > set_pud(pudp, pfn_pud(__phys_to_pfn(phys), sect_prot)); > return 1; > } > @@ -953,6 +957,9 @@ int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot) > return 0; > > BUG_ON(phys & ~PMD_MASK); > + if (pmd_val(*pmd) && !pmd_huge(*pmd)) > + free_page((unsigned long)__va(pmd_val(*pmd))); > + > set_pmd(pmdp, pfn_pmd(__phys_to_pfn(phys), sect_prot)); > return 1; > } > Thanks, M. -- Jazz is not dead. It just smells funny...
