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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup
Date: Thu,  8 Aug 2019 12:48:26 +0000 (UTC)	[thread overview]
Message-ID: <bef479514f4c08329fa649f67735df8918bc0976.1565268248.git.christophe.leroy@c-s.fr> (raw)

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


WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc/64e: drop stale call to smp_processor_id() which hangs SMP startup
Date: Thu,  8 Aug 2019 12:48:26 +0000 (UTC)	[thread overview]
Message-ID: <bef479514f4c08329fa649f67735df8918bc0976.1565268248.git.christophe.leroy@c-s.fr> (raw)

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


             reply	other threads:[~2019-08-08 12:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08 12:48 Christophe Leroy [this message]
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

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