linux-kernel - Re: [PATCH V2] SelfTest: KVM: Drop Asserts for madvise MADV

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Date:   Mon, 24 Dec 2018 16:56:50 +0200
From:   Ahmed Soliman <ahmedsoliman@...a.vt.edu>
To:     Shuah Khan <shuah@...nel.org>, Andrew Jones <drjones@...hat.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Colin Ian King <colin.king@...onical.com>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hossam Hassan <7ossam9063@...il.com>,
        Ahmed Lotfy <A7med.lotfey@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Anders Roxell <anders.roxell@...aro.org>
Subject: Re: [PATCH V2] SelfTest: KVM: Drop Asserts for madvise
 MADV_NOHUGEPAGE failure

Kind reminder to merge my patch into next

thanks.

On Fri, Nov 16, 2018 at 2:59 PM Andrew Jones <drjones@...hat.com> wrote:
>
> On Fri, Nov 16, 2018 at 01:50:55PM +0200, Ahmed Abd El Mawgood wrote:
> > From: Ahmed Abd El Mawgood <ahmedsoliman@...a.vt.edu>
> >
> > madvise() returns -1 without CONFIG_TRANSPARENT_HUGEPAGE=y. That would
> > trigger asserts when checking for return value of madvice. Following
> > similar decision to [1]. I thought it is ok to assume that madvise()
> > MADV_NOHUGEPAGE failures implies that THP is not supported by host kernel.
> >
> > Other options was to check for Transparent Huge Page support in
> > /sys/kernel/mm/transparent_hugepage/enabled.
> >
> > -- links --
> > [1] https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg04514.html
> >
> > Signed-off-by: Ahmed Abd El Mawgood <ahmedsoliman@...a.vt.edu>
> > ---
> >  tools/testing/selftests/kvm/lib/kvm_util.c | 21 +++++++++++++++------
> >  1 file changed, 15 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> > index 1b41e71283d5..437c5bb48061 100644
> > --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> > @@ -586,14 +586,23 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> >                                src_type == VM_MEM_SRC_ANONYMOUS_THP ?  huge_page_size : 1);
> >
> >       /* As needed perform madvise */
> > -     if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {
> > +     if (src_type == VM_MEM_SRC_ANONYMOUS) {
> > +             /*
> > +              * Neglect madvise error because it is ok to not have THP
> > +              * support in this case.
> > +              */
> > +             madvise(region->host_mem, npages * vm->page_size,
> > +                     MADV_NOHUGEPAGE);
> > +     } else if (src_type == VM_MEM_SRC_ANONYMOUS_THP) {
> >               ret = madvise(region->host_mem, npages * vm->page_size,
> > -                          src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
> > +                     MADV_HUGEPAGE);
> >               TEST_ASSERT(ret == 0, "madvise failed,\n"
> > -                         "  addr: %p\n"
> > -                         "  length: 0x%lx\n"
> > -                         "  src_type: %x",
> > -                         region->host_mem, npages * vm->page_size, src_type);
> > +                     "Does the kernel have CONFIG_TRANSPARENT_HUGEPAGE=y\n"
> > +                     "  addr: %p\n"
> > +                     "  length: 0x%lx\n"
> > +                     "  src_type: %x\n",
> > +                     region->host_mem, npages * vm->page_size,
> > +                     src_type);
> >       }
> >
> >       region->unused_phy_pages = sparsebit_alloc();
> > --
> > 2.18.1
> >
>
> Reviewed-by: Andrew Jones <drjones@...hat.com>



-- 
Junior Researcher, IoT and Cyber Security lab, SmartCI, Alexandria
University, & CIS @  VMI