From: Marc Zyngier <marc.zyngier@arm.com> To: Chintan Pandya <cpandya@codeaurora.org>, catalin.marinas@arm.com, will.deacon@arm.com, arnd@arndb.de Cc: mark.rutland@arm.com, ard.biesheuvel@linaro.org, james.morse@arm.com, kristina.martsenko@arm.com, takahiro.akashi@linaro.org, gregkh@linuxfoundation.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, akpm@linux-foundation.org, toshi.kani@hpe.com Subject: Re: [PATCH v1 3/4] arm64: Fix the page leak in pud/pmd_set_huge Date: Wed, 14 Mar 2018 10:35:55 +0000 [thread overview] Message-ID: <4b955357-23a0-c0ac-4407-79a1198e1913@arm.com> (raw) In-Reply-To: <1521017305-28518-4-git-send-email-cpandya@codeaurora.org> 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@codeaurora.org> > --- > 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...
WARNING: multiple messages have this Message-ID (diff)
From: marc.zyngier@arm.com (Marc Zyngier) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v1 3/4] arm64: Fix the page leak in pud/pmd_set_huge Date: Wed, 14 Mar 2018 10:35:55 +0000 [thread overview] Message-ID: <4b955357-23a0-c0ac-4407-79a1198e1913@arm.com> (raw) In-Reply-To: <1521017305-28518-4-git-send-email-cpandya@codeaurora.org> 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@codeaurora.org> > --- > 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...
next prev parent reply other threads:[~2018-03-14 10:35 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-14 8:48 [PATCH v1 0/4] Fix issues with huge mapping in ioremap Chintan Pandya 2018-03-14 8:48 ` Chintan Pandya 2018-03-14 8:48 ` [PATCH v1 1/4] asm/tlbflush: Add flush_tlb_pgtable() for ARM64 Chintan Pandya 2018-03-14 8:48 ` Chintan Pandya 2018-03-16 8:26 ` kbuild test robot 2018-03-16 8:26 ` kbuild test robot 2018-03-16 8:26 ` kbuild test robot 2018-03-16 8:26 ` kbuild test robot 2018-03-14 8:48 ` [PATCH v1 2/4] ioremap: Invalidate TLB after huge mappings Chintan Pandya 2018-03-14 8:48 ` Chintan Pandya 2018-03-14 10:48 ` Mark Rutland 2018-03-14 10:48 ` Mark Rutland 2018-03-14 11:20 ` Chintan Pandya 2018-03-14 11:20 ` Chintan Pandya 2018-03-14 11:48 ` Mark Rutland 2018-03-14 11:48 ` Mark Rutland 2018-03-14 8:48 ` [PATCH v1 3/4] arm64: Fix the page leak in pud/pmd_set_huge Chintan Pandya 2018-03-14 8:48 ` Chintan Pandya 2018-03-14 10:35 ` Marc Zyngier [this message] 2018-03-14 10:35 ` Marc Zyngier 2018-03-14 10:53 ` Mark Rutland 2018-03-14 10:53 ` Mark Rutland 2018-03-14 11:27 ` Chintan Pandya 2018-03-14 11:27 ` Chintan Pandya 2018-03-14 11:50 ` Mark Rutland 2018-03-14 11:50 ` Mark Rutland 2018-03-16 14:50 ` kbuild test robot 2018-03-16 14:50 ` kbuild test robot 2018-03-16 14:50 ` kbuild test robot 2018-03-16 14:50 ` kbuild test robot 2018-03-14 8:48 ` [PATCH v1 4/4] Revert "arm64: Enforce BBM for huge IO/VMAP mappings" Chintan Pandya 2018-03-14 8:48 ` Chintan Pandya 2018-03-14 10:46 ` Marc Zyngier 2018-03-14 10:46 ` Marc Zyngier 2018-03-14 11:32 ` Chintan Pandya 2018-03-14 11:32 ` Chintan Pandya 2018-03-14 14:38 ` [PATCH v1 0/4] Fix issues with huge mapping in ioremap Kani, Toshi 2018-03-14 14:38 ` Kani, Toshi 2018-03-15 7:17 ` Chintan Pandya 2018-03-15 7:17 ` Chintan Pandya 2018-03-15 14:38 ` Kani, Toshi 2018-03-15 14:38 ` Kani, Toshi
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