On 2016-03-10 01:04:24 [+0530], Aneesh Kumar K.V wrote: > Sebastian Andrzej Siewior <bige...@linutronix.de> 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 <aneesh.ku...@linux.vnet.ibm.com> > > > Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> > > Cc: Christoph Lameter <c...@linux.com> > > Cc: Michael Ellerman <m...@ellerman.id.au> > > Cc: <sta...@vger.kernel.org> > > Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de> > > --- > > 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 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
