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From: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>, <stable@vger.kernel.org>,
	<wsd_upstream@mediatek.com>,
	Eason-YH Lin <eason-yh.lin@mediatek.com>,
	Kobe-CP Wu <kobe-cp.wu@mediatek.com>,
	Jeff-CC Hsu <jeff-cc.hsu@mediatek.com>,
	Cheng Jui Wang <cheng-jui.wang@mediatek.com>
Subject: [PATCH] lockdep: Correct lock_classes index mapping
Date: Thu, 10 Feb 2022 18:50:11 +0800	[thread overview]
Message-ID: <20220210105011.21712-1-cheng-jui.wang@mediatek.com> (raw)

A kernel exception was hit when trying to dump /proc/lockdep_chains after
lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!":

Unable to handle kernel paging request at virtual address 00054005450e05c3
...
00054005450e05c3] address between user and kernel address ranges
...
pc : [0xffffffece769b3a8] string+0x50/0x10c
lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c
...
 Call trace:
  string+0x50/0x10c
  vsnprintf+0x468/0x69c
  seq_printf+0x8c/0xd8
  print_name+0x64/0xf4
  lc_show+0xb8/0x128
  seq_read_iter+0x3cc/0x5fc
  proc_reg_read_iter+0xdc/0x1d4

The cause of the problem is the function lock_chain_get_class() will
shift lock_classes index by 1, but the index don't need to be shifted
anymore since commit 01bb6f0af992 ("locking/lockdep: Change the range of
class_idx in held_lock struct") already change the index to start from
0.

The lock_classes[-1] located at chain_hlocks array. When printing
lock_classes[-1] after the chain_hlocks entries are modified, the
exception happened.

The output of lockdep_chains are incorrect due to this problem too.

Fixes: f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey")

Signed-off-by: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
---
 kernel/locking/lockdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4a882f83aeb9..f8a0212189ca 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3462,7 +3462,7 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
 	u16 chain_hlock = chain_hlocks[chain->base + i];
 	unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
 
-	return lock_classes + class_idx - 1;
+	return lock_classes + class_idx;
 }
 
 /*
@@ -3530,7 +3530,7 @@ static void print_chain_keys_chain(struct lock_chain *chain)
 		hlock_id = chain_hlocks[chain->base + i];
 		chain_key = print_chain_key_iteration(hlock_id, chain_key);
 
-		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1);
+		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
 		printk("\n");
 	}
 }
-- 
2.18.0


WARNING: multiple messages have this Message-ID (diff)
From: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>, <stable@vger.kernel.org>,
	<wsd_upstream@mediatek.com>,
	Eason-YH Lin <eason-yh.lin@mediatek.com>,
	Kobe-CP Wu <kobe-cp.wu@mediatek.com>,
	Jeff-CC Hsu <jeff-cc.hsu@mediatek.com>,
	 Cheng Jui Wang <cheng-jui.wang@mediatek.com>
Subject: [PATCH] lockdep: Correct lock_classes index mapping
Date: Thu, 10 Feb 2022 18:50:11 +0800	[thread overview]
Message-ID: <20220210105011.21712-1-cheng-jui.wang@mediatek.com> (raw)

A kernel exception was hit when trying to dump /proc/lockdep_chains after
lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!":

Unable to handle kernel paging request at virtual address 00054005450e05c3
...
00054005450e05c3] address between user and kernel address ranges
...
pc : [0xffffffece769b3a8] string+0x50/0x10c
lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c
...
 Call trace:
  string+0x50/0x10c
  vsnprintf+0x468/0x69c
  seq_printf+0x8c/0xd8
  print_name+0x64/0xf4
  lc_show+0xb8/0x128
  seq_read_iter+0x3cc/0x5fc
  proc_reg_read_iter+0xdc/0x1d4

The cause of the problem is the function lock_chain_get_class() will
shift lock_classes index by 1, but the index don't need to be shifted
anymore since commit 01bb6f0af992 ("locking/lockdep: Change the range of
class_idx in held_lock struct") already change the index to start from
0.

The lock_classes[-1] located at chain_hlocks array. When printing
lock_classes[-1] after the chain_hlocks entries are modified, the
exception happened.

The output of lockdep_chains are incorrect due to this problem too.

Fixes: f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey")

Signed-off-by: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
---
 kernel/locking/lockdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4a882f83aeb9..f8a0212189ca 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3462,7 +3462,7 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
 	u16 chain_hlock = chain_hlocks[chain->base + i];
 	unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
 
-	return lock_classes + class_idx - 1;
+	return lock_classes + class_idx;
 }
 
 /*
@@ -3530,7 +3530,7 @@ static void print_chain_keys_chain(struct lock_chain *chain)
 		hlock_id = chain_hlocks[chain->base + i];
 		chain_key = print_chain_key_iteration(hlock_id, chain_key);
 
-		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1);
+		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
 		printk("\n");
 	}
 }
-- 
2.18.0


_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

WARNING: multiple messages have this Message-ID (diff)
From: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>, <stable@vger.kernel.org>,
	<wsd_upstream@mediatek.com>,
	Eason-YH Lin <eason-yh.lin@mediatek.com>,
	Kobe-CP Wu <kobe-cp.wu@mediatek.com>,
	Jeff-CC Hsu <jeff-cc.hsu@mediatek.com>,
	 Cheng Jui Wang <cheng-jui.wang@mediatek.com>
Subject: [PATCH] lockdep: Correct lock_classes index mapping
Date: Thu, 10 Feb 2022 18:50:11 +0800	[thread overview]
Message-ID: <20220210105011.21712-1-cheng-jui.wang@mediatek.com> (raw)

A kernel exception was hit when trying to dump /proc/lockdep_chains after
lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!":

Unable to handle kernel paging request at virtual address 00054005450e05c3
...
00054005450e05c3] address between user and kernel address ranges
...
pc : [0xffffffece769b3a8] string+0x50/0x10c
lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c
...
 Call trace:
  string+0x50/0x10c
  vsnprintf+0x468/0x69c
  seq_printf+0x8c/0xd8
  print_name+0x64/0xf4
  lc_show+0xb8/0x128
  seq_read_iter+0x3cc/0x5fc
  proc_reg_read_iter+0xdc/0x1d4

The cause of the problem is the function lock_chain_get_class() will
shift lock_classes index by 1, but the index don't need to be shifted
anymore since commit 01bb6f0af992 ("locking/lockdep: Change the range of
class_idx in held_lock struct") already change the index to start from
0.

The lock_classes[-1] located at chain_hlocks array. When printing
lock_classes[-1] after the chain_hlocks entries are modified, the
exception happened.

The output of lockdep_chains are incorrect due to this problem too.

Fixes: f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey")

Signed-off-by: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
---
 kernel/locking/lockdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4a882f83aeb9..f8a0212189ca 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3462,7 +3462,7 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
 	u16 chain_hlock = chain_hlocks[chain->base + i];
 	unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
 
-	return lock_classes + class_idx - 1;
+	return lock_classes + class_idx;
 }
 
 /*
@@ -3530,7 +3530,7 @@ static void print_chain_keys_chain(struct lock_chain *chain)
 		hlock_id = chain_hlocks[chain->base + i];
 		chain_key = print_chain_key_iteration(hlock_id, chain_key);
 
-		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1);
+		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
 		printk("\n");
 	}
 }
-- 
2.18.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

             reply	other threads:[~2022-02-10 10:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-10 10:50 Cheng Jui Wang [this message]
2022-02-10 10:50 ` [PATCH] lockdep: Correct lock_classes index mapping Cheng Jui Wang
2022-02-10 10:50 ` Cheng Jui Wang
2022-02-10 12:45 ` Boqun Feng
2022-02-10 12:45   ` Boqun Feng
2022-02-10 12:45   ` Boqun Feng
2022-02-10 12:53 ` Greg KH
2022-02-10 12:53   ` Greg KH
2022-02-10 12:53   ` Greg KH
2022-02-14 10:37 ` [tip: locking/urgent] " tip-bot2 for Cheng Jui Wang

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