Re: BUG: Bad page state in process true pfn:a8fed on arm

[Anders Roxell]

On Tue, 25 Aug 2020 at 10:32, Mike Rapoport <rppt@xxxxxxxxxxxxx> wrote:
>
> On Tue, Aug 25, 2020 at 01:03:53PM +0530, Naresh Kamboju wrote:
> > On Mon, 24 Aug 2020 at 16:36, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> > >
> > > On Mon, Aug 24, 2020 at 03:14:55PM +0530, Naresh Kamboju wrote:
> > > > [   67.545247] BUG: Bad page state in process true  pfn:a8fed
> > > > [   67.550767] page:9640c0ab refcount:0 mapcount:-1024
> > >
> > > Somebody freed a page table without calling __ClearPageTable() on it.
> >
> > After running git bisect on this problem,
> > The first suspecting of this problem on arm architecture this patch.
> > 424efe723f7717430bec7c93b4d28bba73e31cf6
> > ("mm: account PMD tables like PTE tables ")
> >
> > Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> > Reported-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
>
> Can you please check if this fix helps?

That fixed the problem.

Cheers,
Anders

>
> diff --git a/arch/arm/include/asm/tlb.h b/arch/arm/include/asm/tlb.h
> index 9415222b49ad..b8cbe03ad260 100644
> --- a/arch/arm/include/asm/tlb.h
> +++ b/arch/arm/include/asm/tlb.h
> @@ -59,6 +59,7 @@ __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
>  #ifdef CONFIG_ARM_LPAE
>         struct page *page = virt_to_page(pmdp);
>
> +       pgtable_pmd_page_dtor(page);
>         tlb_remove_table(tlb, page);
>  #endif
>  }
>
> > Additional information:
> > We have tested linux next by reverting this patch and confirmed
> > that the reported BUG is not reproduced.
> >
> > These configs enabled on the running device,
> >
> > CONFIG_TRANSPARENT_HUGEPAGE=y
> > CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y
> >
> >
> > -- Suspecting patch --
> > commit 424efe723f7717430bec7c93b4d28bba73e31cf6
> > Author: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> > Date:   Thu Aug 20 10:01:30 2020 +1000
> >
> >     mm: account PMD tables like PTE tables
> >
> >     We account the PTE level of the page tables to the process in order to
> >     make smarter OOM decisions and help diagnose why memory is fragmented.
> >     For these same reasons, we should account pages allocated for PMDs.  With
> >     larger process address spaces and ASLR, the number of PMDs in use is
> >     higher than it used to be so the inaccuracy is starting to matter.
> >
> >     Link: http://lkml.kernel.org/r/20200627184642.GF25039@xxxxxxxxxxxxxxxxxxxx
> >     Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> >     Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> >     Cc: Abdul Haleem <abdhalee@xxxxxxxxxxxxxxxxxx>
> >     Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> >     Cc: Arnd Bergmann <arnd@xxxxxxxx>
> >     Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> >     Cc: Joerg Roedel <joro@xxxxxxxxxx>
> >     Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
> >     Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> >     Cc: Satheesh Rajendran <sathnaga@xxxxxxxxxxxxxxxxxx>
> >     Cc: Stafford Horne <shorne@xxxxxxxxx>
> >     Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> >     Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index b0a15ee77b8a..a4e5b806347c 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -2239,7 +2239,7 @@ static inline spinlock_t *pmd_lockptr(struct
> > mm_struct *mm, pmd_t *pmd)
> >   return ptlock_ptr(pmd_to_page(pmd));
> >  }
> >
> > -static inline bool pgtable_pmd_page_ctor(struct page *page)
> > +static inline bool pmd_ptlock_init(struct page *page)
> >  {
> >  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >   page->pmd_huge_pte = NULL;
> > @@ -2247,7 +2247,7 @@ static inline bool pgtable_pmd_page_ctor(struct
> > page *page)
> >   return ptlock_init(page);
> >  }
> >
> > -static inline void pgtable_pmd_page_dtor(struct page *page)
> > +static inline void pmd_ptlock_free(struct page *page)
> >  {
> >  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >   VM_BUG_ON_PAGE(page->pmd_huge_pte, page);
> > @@ -2264,8 +2264,8 @@ static inline spinlock_t *pmd_lockptr(struct
> > mm_struct *mm, pmd_t *pmd)
> >   return &mm->page_table_lock;
> >  }
> >
> > -static inline bool pgtable_pmd_page_ctor(struct page *page) { return true; }
> > -static inline void pgtable_pmd_page_dtor(struct page *page) {}
> > +static inline bool pmd_ptlock_init(struct page *page) { return true; }
> > +static inline void pmd_ptlock_free(struct page *page) {}
> >
> >  #define pmd_huge_pte(mm, pmd) ((mm)->pmd_huge_pte)
> >
> > @@ -2278,6 +2278,22 @@ static inline spinlock_t *pmd_lock(struct
> > mm_struct *mm, pmd_t *pmd)
> >   return ptl;
> >  }
> >
> > +static inline bool pgtable_pmd_page_ctor(struct page *page)
> > +{
> > + if (!pmd_ptlock_init(page))
> > + return false;
> > + __SetPageTable(page);
> > + inc_zone_page_state(page, NR_PAGETABLE);
> > + return true;
> > +}
> > +
> > +static inline void pgtable_pmd_page_dtor(struct page *page)
> > +{
> > + pmd_ptlock_free(page);
> > + __ClearPageTable(page);
> > + dec_zone_page_state(page, NR_PAGETABLE);
> > +}
> > +
> >  /*
> >   * No scalability reason to split PUD locks yet, but follow the same pattern
> >   * as the PMD locks to make it easier if we decide to.  The VM should not be
> >
> >
> >
> >
> > - Naresh
>
> --
> Sincerely yours,
> Mike.