linux-kernel - Re: jemalloc testsuite stalls in memset

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Message-ID: <20161221235422.GA12727@bbox>
Date:   Thu, 22 Dec 2016 08:54:22 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Andreas Schwab <schwab@...e.de>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        mbrugger@...e.de, linux-mm@...ck.org, Jason Evans <je@...com>
Subject: Re: jemalloc testsuite stalls in memset

Hello, Andreas

Sorry for long delay. I was on vacation.

On Fri, Dec 16, 2016 at 03:16:20PM +0100, Andreas Schwab wrote:
> On Dez 16 2016, Minchan Kim <minchan@...nel.org> wrote:
> 
> > Below helps?
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index e10a4fe..dc37c9a 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -1611,6 +1611,7 @@ int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> >  			tlb->fullmm);
> >  		orig_pmd = pmd_mkold(orig_pmd);
> >  		orig_pmd = pmd_mkclean(orig_pmd);
> > +		orig_pmd = pmd_wrprotect(orig_pmd);
> >  
> >  		set_pmd_at(mm, addr, pmd, orig_pmd);
> >  		tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
> 
> Thanks, this fixes the issue (tested with 4.9).

It was a quick hack to know what exact problem is there and your confirming
helped a lot to understand the problem clear.

More right approach is to support pmd dirty handling in general page fault
handler rather than tweaking MADV_FREE. I just sent a new patch with Ccing
you.

Could you test it, please?
Thanks!