* [PATCH] powerpc: mm: fixup preempt undefflow with huge pages
@ 2016-03-07 13:55 Sebastian Andrzej Siewior
2016-03-07 15:34 ` Aneesh Kumar K.V
0 siblings, 1 reply; 10+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-03-07 13:55 UTC (permalink / raw)
To: linuxppc-dev, Benjamin Herrenschmidt
Cc: Paul Mackerras, Michael Ellerman, Aneesh Kumar K.V,
Christoph Lameter, Tiejun Chen, Scott Wood
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.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Tiejun Chen <tiejun.chen@windriver.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/powerpc/mm/hugetlbpage.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 744e24bcb85c..9e8919b39640 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -414,7 +414,7 @@ static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
{
struct hugepd_freelist **batchp;
- batchp = this_cpu_ptr(&hugepd_freelist_cur);
+ batchp = get_cpu_ptr(&hugepd_freelist_cur);
if (atomic_read(&tlb->mm->mm_users) < 2 ||
cpumask_equal(mm_cpumask(tlb->mm),
--
2.7.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-07 13:55 [PATCH] powerpc: mm: fixup preempt undefflow with huge pages Sebastian Andrzej Siewior
@ 2016-03-07 15:34 ` Aneesh Kumar K.V
2016-03-07 23:41 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 10+ messages in thread
From: Aneesh Kumar K.V @ 2016-03-07 15:34 UTC (permalink / raw)
To: Sebastian Andrzej Siewior, linuxppc-dev, Benjamin Herrenschmidt
Cc: Paul Mackerras, Michael Ellerman, Christoph Lameter, Tiejun Chen,
Scott Wood
Sebastian Andrzej Siewior <bigeasy@linutronix.de> 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.
>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Tiejun Chen <tiejun.chen@windriver.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> arch/powerpc/mm/hugetlbpage.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index 744e24bcb85c..9e8919b39640 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -414,7 +414,7 @@ static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
> {
> struct hugepd_freelist **batchp;
>
> - batchp = this_cpu_ptr(&hugepd_freelist_cur);
> + batchp = get_cpu_ptr(&hugepd_freelist_cur);
>
> if (atomic_read(&tlb->mm->mm_users) < 2 ||
> cpumask_equal(mm_cpumask(tlb->mm),
IMHO it would better if we do
batchp = get_cpu_var(hugepd_freelist_cpu);
so that it match the existing
put_cpu_var(hugepd_freelist_cur);
While you are there, can you also fix the wrong indentation on line 423
?
-aneesh
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-07 15:34 ` Aneesh Kumar K.V
@ 2016-03-07 23:41 ` Benjamin Herrenschmidt
2016-03-08 8:08 ` Sebastian Andrzej Siewior
2016-03-08 9:03 ` [PATCH v2] " Sebastian Andrzej Siewior
0 siblings, 2 replies; 10+ messages in thread
From: Benjamin Herrenschmidt @ 2016-03-07 23:41 UTC (permalink / raw)
To: Aneesh Kumar K.V, Sebastian Andrzej Siewior, linuxppc-dev
Cc: Paul Mackerras, Michael Ellerman, Christoph Lameter, Tiejun Chen,
Scott Wood
On Mon, 2016-03-07 at 21:04 +0530, Aneesh Kumar K.V wrote:
> Sebastian Andrzej Siewior <bigeasy@linutronix.de> writes:
>
> While you are there, can you also fix the wrong indentation on line
> 423
> ?
.../...
Also this looks like stable material no ?
Cheers,
Ben.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-07 23:41 ` Benjamin Herrenschmidt
@ 2016-03-08 8:08 ` Sebastian Andrzej Siewior
2016-03-08 9:03 ` [PATCH v2] " Sebastian Andrzej Siewior
1 sibling, 0 replies; 10+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-03-08 8:08 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Aneesh Kumar K.V, linuxppc-dev
Cc: Paul Mackerras, Michael Ellerman, Christoph Lameter, Tiejun Chen,
Scott Wood
On 03/08/2016 12:41 AM, Benjamin Herrenschmidt wrote:
> On Mon, 2016-03-07 at 21:04 +0530, Aneesh Kumar K.V wrote:
>> Sebastian Andrzej Siewior <bigeasy@linutronix.de> writes:
>>
>> While you are there, can you also fix the wrong indentation on line
>> 423
>> ?
>
> .../...
>
> Also this looks like stable material no ?
Yes, I had a stable tag attached. I am going to resend it with the
additional changes Aneesh asked for.
> Cheers,
> Ben.
>
Sebastian
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-07 23:41 ` Benjamin Herrenschmidt
2016-03-08 8:08 ` Sebastian Andrzej Siewior
@ 2016-03-08 9:03 ` Sebastian Andrzej Siewior
2016-03-09 19:34 ` Aneesh Kumar K.V
2016-03-30 23:29 ` [v2] " Michael Ellerman
1 sibling, 2 replies; 10+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-03-08 9:03 UTC (permalink / raw)
To: Benjamin Herrenschmidt
Cc: Aneesh Kumar K.V, linuxppc-dev, Paul Mackerras, Michael Ellerman,
Christoph Lameter, Scott Wood
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.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v1=E2=80=A6v2: - 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;
=20
- batchp =3D this_cpu_ptr(&hugepd_freelist_cur);
+ batchp =3D &get_cpu_var(hugepd_freelist_cur);
=20
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;
}
=20
--=20
2.7.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-08 9:03 ` [PATCH v2] " Sebastian Andrzej Siewior
@ 2016-03-09 19:34 ` Aneesh Kumar K.V
2016-03-29 13:40 ` Sebastian Andrzej Siewior
2016-03-30 23:29 ` [v2] " Michael Ellerman
1 sibling, 1 reply; 10+ messages in thread
From: Aneesh Kumar K.V @ 2016-03-09 19:34 UTC (permalink / raw)
To: Sebastian Andrzej Siewior, Benjamin Herrenschmidt
Cc: linuxppc-dev, Paul Mackerras, Michael Ellerman,
Christoph Lameter, Scott Wood
Sebastian Andrzej Siewior <bigeasy@linutronix.de> 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 <aneesh.kumar@linux.vnet.ibm.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> v1=E2=80=A6v2: - 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, voi=
d *hugepte)
> {
> struct hugepd_freelist **batchp;
>=20=20
> - batchp =3D this_cpu_ptr(&hugepd_freelist_cur);
> + batchp =3D &get_cpu_var(hugepd_freelist_cur);
>=20=20
> 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;
> }
>=20=20
> --=20
> 2.7.0
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-09 19:34 ` Aneesh Kumar K.V
@ 2016-03-29 13:40 ` Sebastian Andrzej Siewior
2016-03-30 0:41 ` Michael Ellerman
0 siblings, 1 reply; 10+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-03-29 13:40 UTC (permalink / raw)
To: Aneesh Kumar K.V, Benjamin Herrenschmidt, Scott Wood, Michael Ellerman
Cc: Sebastian Andrzej Siewior, Paul Mackerras, Christoph Lameter,
linuxppc-dev
On 2016-03-10 01:04:24 [+0530], Aneesh Kumar K.V wrote:
> Sebastian Andrzej Siewior <bigeasy@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.
> >
>=20
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>=20
> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > Cc: Christoph Lameter <cl@linux.com>
> > Cc: Michael Ellerman <mpe@ellerman.id.au>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> > ---
> > v1=E2=80=A6v2: - 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/hugetlbpag=
e.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, v=
oid *hugepte)
> > {
> > struct hugepd_freelist **batchp;
> > =20
> > - batchp =3D this_cpu_ptr(&hugepd_freelist_cur);
> > + batchp =3D &get_cpu_var(hugepd_freelist_cur);
> > =20
> > 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;
> > }
> > =20
Sebastian
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-29 13:40 ` Sebastian Andrzej Siewior
@ 2016-03-30 0:41 ` Michael Ellerman
2016-03-30 8:17 ` Sebastian Andrzej Siewior
0 siblings, 1 reply; 10+ messages in thread
From: Michael Ellerman @ 2016-03-30 0:41 UTC (permalink / raw)
To: Sebastian Andrzej Siewior, Aneesh Kumar K.V,
Benjamin Herrenschmidt, Scott Wood
Cc: Sebastian Andrzej Siewior, Paul Mackerras, Christoph Lameter,
linuxppc-dev
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 <bigeasy@linutronix.de> 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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-30 0:41 ` Michael Ellerman
@ 2016-03-30 8:17 ` Sebastian Andrzej Siewior
0 siblings, 0 replies; 10+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-03-30 8:17 UTC (permalink / raw)
To: Michael Ellerman, Sebastian Andrzej Siewior, Aneesh Kumar K.V,
Benjamin Herrenschmidt, Scott Wood
Cc: Paul Mackerras, Christoph Lameter, linuxppc-dev
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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [v2] powerpc: mm: fixup preempt undefflow with huge pages
2016-03-08 9:03 ` [PATCH v2] " Sebastian Andrzej Siewior
2016-03-09 19:34 ` Aneesh Kumar K.V
@ 2016-03-30 23:29 ` Michael Ellerman
1 sibling, 0 replies; 10+ messages in thread
From: Michael Ellerman @ 2016-03-30 23:29 UTC (permalink / raw)
To: Sebastian Siewior, Benjamin Herrenschmidt
Cc: Paul Mackerras, Aneesh Kumar K.V, Scott Wood, Christoph Lameter,
linuxppc-dev
On Tue, 2016-08-03 at 09:03:56 UTC, Sebastian Siewior wrote:
> 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.
>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/08a5bb2921e490939f78f38fd0
cheers
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2016-03-30 23:29 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-03-07 13:55 [PATCH] powerpc: mm: fixup preempt undefflow with huge pages Sebastian Andrzej Siewior
2016-03-07 15:34 ` Aneesh Kumar K.V
2016-03-07 23:41 ` Benjamin Herrenschmidt
2016-03-08 8:08 ` Sebastian Andrzej Siewior
2016-03-08 9:03 ` [PATCH v2] " Sebastian Andrzej Siewior
2016-03-09 19:34 ` Aneesh Kumar K.V
2016-03-29 13:40 ` Sebastian Andrzej Siewior
2016-03-30 0:41 ` Michael Ellerman
2016-03-30 8:17 ` Sebastian Andrzej Siewior
2016-03-30 23:29 ` [v2] " Michael Ellerman
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