Re: [PATCH 34/34] mm: dynamically allocate page->ptl if it cannot be embedded to struct page

[Andrey Wagin <avagin@xxxxxxxxx>]

2013/11/20 Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>:
> Andrey Wagin wrote:
>> Hi Kirill,
>>
>> Looks like this patch adds memory leaks.
>> [  116.188310] kmemleak: 15672 new suspected memory leaks (see
>> /sys/kernel/debug/kmemleak)
>> unreferenced object 0xffff8800da45a350 (size 96):
>>   comm "dracut-initqueu", pid 93, jiffies 4294671391 (age 362.277s)
>>   hex dump (first 32 bytes):
>>     07 00 07 00 ad 4e ad de ff ff ff ff 6b 6b 6b 6b  .....N......kkkk
>>     ff ff ff ff ff ff ff ff 80 24 b4 82 ff ff ff ff  .........$......
>>   backtrace:
>>     [<ffffffff817152fe>] kmemleak_alloc+0x5e/0xc0
>>     [<ffffffff811c34f3>] kmem_cache_alloc_trace+0x113/0x290
>>     [<ffffffff811920f7>] __ptlock_alloc+0x27/0x50
>>     [<ffffffff81192849>] __pmd_alloc+0x59/0x170
>>     [<ffffffff81195ffa>] copy_page_range+0x38a/0x3e0
>>     [<ffffffff8105a013>] dup_mm+0x313/0x540
>>     [<ffffffff8105b9da>] copy_process+0x161a/0x1880
>>     [<ffffffff8105c01b>] do_fork+0x8b/0x360
>>     [<ffffffff8105c306>] SyS_clone+0x16/0x20
>>     [<ffffffff81727b79>] stub_clone+0x69/0x90
>>     [<ffffffffffffffff>] 0xffffffffffffffff
>>
>> It's quite serious, because my test host went to panic in a few hours.
>
> Sorry for that.
>
> Could you test patch below.

Yes, it works.

I found this too a few minutes ago:)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index a7cccb6..44c366c 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -62,6 +62,7 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
 void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
 {
        paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
+       pgtable_pmd_page_dtor(virt_to_page(pmd));
        /*
         * NOTE! For PAE, any changes to the top page-directory-pointer-table
         * entries need a full cr3 reload to flush.

Thanks.

>
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index a7cccb6d7fec..7be5809754cf 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -61,6 +61,7 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
>  #if PAGETABLE_LEVELS > 2
>  void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
>  {
> +       struct page *page = virt_to_page(pmd);
>         paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
>         /*
>          * NOTE! For PAE, any changes to the top page-directory-pointer-table
> @@ -69,7 +70,8 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
>  #ifdef CONFIG_X86_PAE
>         tlb->need_flush_all = 1;
>  #endif
> -       tlb_remove_page(tlb, virt_to_page(pmd));
> +       pgtable_pmd_page_dtor(page);
> +       tlb_remove_page(tlb, page);
>  }
>
>  #if PAGETABLE_LEVELS > 3
> --
>  Kirill A. Shutemov
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