Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
On 03/30/2016 02:41 AM, Michael Ellerman wrote: > The merge window just closed, I'm still recovering. > > I've got it in my fixes branch locally, I'll probably push that today to > linux-next. Thank you. > > cheers > Sebastian ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
On Tue, 2016-03-29 at 15:40 +0200, Sebastian Andrzej Siewior wrote: > On 2016-03-10 01:04:24 [+0530], Aneesh Kumar K.V wrote: > > Sebastian Andrzej Siewior writes: > > *ping* > http://patchwork.ozlabs.org/patch/593943/ *pong* The merge window just closed, I'm still recovering. I've got it in my fixes branch locally, I'll probably push that today to linux-next. cheers ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
On 2016-03-10 01:04:24 [+0530], Aneesh Kumar K.V wrote:
> Sebastian Andrzej Siewior writes:
*ping*
http://patchwork.ozlabs.org/patch/593943/
> > [ text/plain ]
> > hugepd_free() used __get_cpu_var() once. Nothing ensured that the code
> > accessing the variable did not migrate from one CPU to another and soon
> > this was noticed by Tiejun Chen in 94b09d755462 ("powerpc/hugetlb:
> > Replace __get_cpu_var with get_cpu_var"). So we had it fixed.
> >
> > Christoph Lameter was doing his __get_cpu_var() replaces and forgot
> > PowerPC. Then he noticed this and sent his fixed up batch again which
> > got applied as 69111bac42f5 ("powerpc: Replace __get_cpu_var uses").
> >
> > The careful reader will noticed one little detail: get_cpu_var() got
> > replaced with this_cpu_ptr(). So now we have a put_cpu_var() which does
> > a preempt_enable() and nothing that does preempt_disable() so we
> > underflow the preempt counter.
> >
>
> Reviewed-by: Aneesh Kumar K.V
>
> > Cc: Benjamin Herrenschmidt
> > Cc: Christoph Lameter
> > Cc: Michael Ellerman
> > Cc:
> > Signed-off-by: Sebastian Andrzej Siewior
> > ---
> > v1…v2: - use get_cpu_var() instead of get_cpu_ptr()
> >- correct indentation of put_cpu_var()
> >
> > arch/powerpc/mm/hugetlbpage.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> > index 744e24bcb85c..4a811ca7ac9d 100644
> > --- a/arch/powerpc/mm/hugetlbpage.c
> > +++ b/arch/powerpc/mm/hugetlbpage.c
> > @@ -414,13 +414,13 @@ static void hugepd_free(struct mmu_gather *tlb, void
> > *hugepte)
> > {
> > struct hugepd_freelist **batchp;
> >
> > - batchp = this_cpu_ptr(&hugepd_freelist_cur);
> > + batchp = &get_cpu_var(hugepd_freelist_cur);
> >
> > if (atomic_read(&tlb->mm->mm_users) < 2 ||
> > cpumask_equal(mm_cpumask(tlb->mm),
> > cpumask_of(smp_processor_id( {
> > kmem_cache_free(hugepte_cache, hugepte);
> > -put_cpu_var(hugepd_freelist_cur);
> > + put_cpu_var(hugepd_freelist_cur);
> > return;
> > }
> >
Sebastian
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Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
Sebastian Andrzej Siewior writes:
> [ text/plain ]
> hugepd_free() used __get_cpu_var() once. Nothing ensured that the code
> accessing the variable did not migrate from one CPU to another and soon
> this was noticed by Tiejun Chen in 94b09d755462 ("powerpc/hugetlb:
> Replace __get_cpu_var with get_cpu_var"). So we had it fixed.
>
> Christoph Lameter was doing his __get_cpu_var() replaces and forgot
> PowerPC. Then he noticed this and sent his fixed up batch again which
> got applied as 69111bac42f5 ("powerpc: Replace __get_cpu_var uses").
>
> The careful reader will noticed one little detail: get_cpu_var() got
> replaced with this_cpu_ptr(). So now we have a put_cpu_var() which does
> a preempt_enable() and nothing that does preempt_disable() so we
> underflow the preempt counter.
>
Reviewed-by: Aneesh Kumar K.V
> Cc: Benjamin Herrenschmidt
> Cc: Christoph Lameter
> Cc: Michael Ellerman
> Cc:
> Signed-off-by: Sebastian Andrzej Siewior
> ---
> v1…v2: - use get_cpu_var() instead of get_cpu_ptr()
>- correct indentation of put_cpu_var()
>
> arch/powerpc/mm/hugetlbpage.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index 744e24bcb85c..4a811ca7ac9d 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -414,13 +414,13 @@ static void hugepd_free(struct mmu_gather *tlb, void
> *hugepte)
> {
> struct hugepd_freelist **batchp;
>
> - batchp = this_cpu_ptr(&hugepd_freelist_cur);
> + batchp = &get_cpu_var(hugepd_freelist_cur);
>
> if (atomic_read(&tlb->mm->mm_users) < 2 ||
> cpumask_equal(mm_cpumask(tlb->mm),
> cpumask_of(smp_processor_id( {
> kmem_cache_free(hugepte_cache, hugepte);
> -put_cpu_var(hugepd_freelist_cur);
> + put_cpu_var(hugepd_freelist_cur);
> return;
> }
>
> --
> 2.7.0
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