* [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup
@ 2019-08-08 12:48 Christophe Leroy
2019-08-08 21:12 ` Chris Packham
2019-08-12 13:15 ` Michael Ellerman
0 siblings, 2 replies; 3+ messages in thread
From: Christophe Leroy @ 2019-08-08 12:48 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, Chris Packham
Cc: linux-kernel, linuxppc-dev
Santa commit ebb9d30a6a74 ("powerpc/mm: any thread in one core can be
the first to setup TLB1") removed the need to know the cpu_id in
early_init_this_mmu(), but the call to smp_processor_id() which was
marked __maybe_used remained.
Since commit ed1cd6deb013 ("powerpc: Activate
CONFIG_THREAD_INFO_IN_TASK") thread_info cannot be reached before mmu
is properly set up.
Drop this stale call to smp_processor_id() which make SMP hang
when CONFIG_PREEMPT is set.
Reported-by: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Fixes: ebb9d30a6a74 ("powerpc/mm: any thread in one core can be the first to setup TLB1")
Link: https://github.com/linuxppc/issues/issues/264
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: stable@vger.kernel.org
---
arch/powerpc/mm/nohash/tlb.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/powerpc/mm/nohash/tlb.c b/arch/powerpc/mm/nohash/tlb.c
index d4acf6fa0596..bf60983a58c7 100644
--- a/arch/powerpc/mm/nohash/tlb.c
+++ b/arch/powerpc/mm/nohash/tlb.c
@@ -630,7 +630,6 @@ static void early_init_this_mmu(void)
#ifdef CONFIG_PPC_FSL_BOOK3E
if (mmu_has_feature(MMU_FTR_TYPE_FSL_E)) {
unsigned int num_cams;
- int __maybe_unused cpu = smp_processor_id();
bool map = true;
/* use a quarter of the TLBCAM for bolted linear map */
--
2.13.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup
2019-08-08 12:48 [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup Christophe Leroy
@ 2019-08-08 21:12 ` Chris Packham
2019-08-12 13:15 ` Michael Ellerman
1 sibling, 0 replies; 3+ messages in thread
From: Chris Packham @ 2019-08-08 21:12 UTC (permalink / raw)
To: christophe.leroy, paulus, mpe, benh; +Cc: linuxppc-dev, linux-kernel
Hi Christophe,
On Thu, 2019-08-08 at 12:48 +0000, Christophe Leroy wrote:
> Santa commit ebb9d30a6a74 ("powerpc/mm: any thread in one core can be
> the first to setup TLB1") removed the need to know the cpu_id in
> early_init_this_mmu(), but the call to smp_processor_id() which was
> marked __maybe_used remained.
>
> Since commit ed1cd6deb013 ("powerpc: Activate
> CONFIG_THREAD_INFO_IN_TASK") thread_info cannot be reached before mmu
> is properly set up.
>
> Drop this stale call to smp_processor_id() which make SMP hang
> when CONFIG_PREEMPT is set.
>
> Reported-by: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
> Fixes: ebb9d30a6a74 ("powerpc/mm: any thread in one core can be the
> first to setup TLB1")
> Link: https://github.com/linuxppc/issues/issues/264
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: stable@vger.kernel.org
Many thanks for your help.
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
> arch/powerpc/mm/nohash/tlb.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/powerpc/mm/nohash/tlb.c
> b/arch/powerpc/mm/nohash/tlb.c
> index d4acf6fa0596..bf60983a58c7 100644
> --- a/arch/powerpc/mm/nohash/tlb.c
> +++ b/arch/powerpc/mm/nohash/tlb.c
> @@ -630,7 +630,6 @@ static void early_init_this_mmu(void)
> #ifdef CONFIG_PPC_FSL_BOOK3E
> if (mmu_has_feature(MMU_FTR_TYPE_FSL_E)) {
> unsigned int num_cams;
> - int __maybe_unused cpu = smp_processor_id();
> bool map = true;
>
> /* use a quarter of the TLBCAM for bolted linear map
> */
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup
2019-08-08 12:48 [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup Christophe Leroy
2019-08-08 21:12 ` Chris Packham
@ 2019-08-12 13:15 ` Michael Ellerman
1 sibling, 0 replies; 3+ messages in thread
From: Michael Ellerman @ 2019-08-12 13:15 UTC (permalink / raw)
To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras, Chris Packham
Cc: linuxppc-dev, linux-kernel
On Thu, 2019-08-08 at 12:48:26 UTC, Christophe Leroy wrote:
> Santa commit ebb9d30a6a74 ("powerpc/mm: any thread in one core can be
> the first to setup TLB1") removed the need to know the cpu_id in
> early_init_this_mmu(), but the call to smp_processor_id() which was
> marked __maybe_used remained.
>
> Since commit ed1cd6deb013 ("powerpc: Activate
> CONFIG_THREAD_INFO_IN_TASK") thread_info cannot be reached before mmu
> is properly set up.
>
> Drop this stale call to smp_processor_id() which make SMP hang
> when CONFIG_PREEMPT is set.
>
> Reported-by: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
> Fixes: ebb9d30a6a74 ("powerpc/mm: any thread in one core can be the first to setup TLB1")
> Link: https://github.com/linuxppc/issues/issues/264
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: stable@vger.kernel.org
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/b9ee5e04fd77898208c51b1395fa0b5e8536f9b6
cheers
^ permalink raw reply [flat|nested] 3+ messages in thread
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