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From: Chen Jun <chenjun102@huawei.com>
To: <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>
Cc: <akpm@linux-foundation.org>, <catalin.marinas@arm.com>,
	<will@kernel.org>,  <rui.xiang@huawei.com>
Subject: [PATCH 2/2] arm64: stacktrace: Add skip when task == current
Date: Wed, 17 Mar 2021 14:20:50 +0000	[thread overview]
Message-ID: <20210317142050.57712-3-chenjun102@huawei.com> (raw)
In-Reply-To: <20210317142050.57712-1-chenjun102@huawei.com>

On ARM64, cat /sys/kernel/debug/page_owner, all pages return the same
stack:
 stack_trace_save+0x4c/0x78
 register_early_stack+0x34/0x70
 init_page_owner+0x34/0x230
 page_ext_init+0x1bc/0x1dc

The reason is that:
check_recursive_alloc always return 1 because that
entries[0] is always equal to ip (__set_page_owner+0x3c/0x60).

The root cause is that:
commit 5fc57df2f6fd ("arm64: stacktrace: Convert to ARCH_STACKWALK")
make the save_trace save 2 more entries.

Add skip in arch_stack_walk when task == current.

Fixes: 5fc57df2f6fd ("arm64: stacktrace: Convert to ARCH_STACKWALK")
Signed-off-by: Chen Jun <chenjun102@huawei.com>
---
 arch/arm64/kernel/stacktrace.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ad20981..c26b0ac 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -201,11 +201,12 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 
 	if (regs)
 		start_backtrace(&frame, regs->regs[29], regs->pc);
-	else if (task == current)
+	else if (task == current) {
+		((struct stacktrace_cookie *)cookie)->skip += 2;
 		start_backtrace(&frame,
 				(unsigned long)__builtin_frame_address(0),
 				(unsigned long)arch_stack_walk);
-	else
+	} else
 		start_backtrace(&frame, thread_saved_fp(task),
 				thread_saved_pc(task));
 
-- 
2.9.4


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Chen Jun <chenjun102@huawei.com>
To: <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>
Cc: <akpm@linux-foundation.org>, <catalin.marinas@arm.com>,
	<will@kernel.org>, <rui.xiang@huawei.com>
Subject: [PATCH 2/2] arm64: stacktrace: Add skip when task == current
Date: Wed, 17 Mar 2021 14:20:50 +0000	[thread overview]
Message-ID: <20210317142050.57712-3-chenjun102@huawei.com> (raw)
In-Reply-To: <20210317142050.57712-1-chenjun102@huawei.com>

On ARM64, cat /sys/kernel/debug/page_owner, all pages return the same
stack:
 stack_trace_save+0x4c/0x78
 register_early_stack+0x34/0x70
 init_page_owner+0x34/0x230
 page_ext_init+0x1bc/0x1dc

The reason is that:
check_recursive_alloc always return 1 because that
entries[0] is always equal to ip (__set_page_owner+0x3c/0x60).

The root cause is that:
commit 5fc57df2f6fd ("arm64: stacktrace: Convert to ARCH_STACKWALK")
make the save_trace save 2 more entries.

Add skip in arch_stack_walk when task == current.

Fixes: 5fc57df2f6fd ("arm64: stacktrace: Convert to ARCH_STACKWALK")
Signed-off-by: Chen Jun <chenjun102@huawei.com>
---
 arch/arm64/kernel/stacktrace.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ad20981..c26b0ac 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -201,11 +201,12 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 
 	if (regs)
 		start_backtrace(&frame, regs->regs[29], regs->pc);
-	else if (task == current)
+	else if (task == current) {
+		((struct stacktrace_cookie *)cookie)->skip += 2;
 		start_backtrace(&frame,
 				(unsigned long)__builtin_frame_address(0),
 				(unsigned long)arch_stack_walk);
-	else
+	} else
 		start_backtrace(&frame, thread_saved_fp(task),
 				thread_saved_pc(task));
 
-- 
2.9.4


  parent reply	other threads:[~2021-03-17 14:25 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-17 14:20 [PATCH 0/2] Fix page_owner broken on arm64 Chen Jun
2021-03-17 14:20 ` Chen Jun
2021-03-17 14:20 ` [PATCH 1/2] stacktrace: Move struct stacktrace_cookie to stacktrace.h Chen Jun
2021-03-17 14:20   ` Chen Jun
2021-03-17 14:20 ` Chen Jun [this message]
2021-03-17 14:20   ` [PATCH 2/2] arm64: stacktrace: Add skip when task == current Chen Jun
2021-03-17 18:36   ` Catalin Marinas
2021-03-17 18:36     ` Catalin Marinas
2021-03-17 19:34     ` Mark Rutland
2021-03-17 19:34       ` Mark Rutland
2021-03-18  3:24       ` chenjun (AM)
2021-03-18  3:24         ` chenjun (AM)
2021-03-18 13:22         ` chenjun (AM)
2021-03-18 13:22           ` chenjun (AM)
2021-03-18 16:17       ` Catalin Marinas
2021-03-18 16:17         ` Catalin Marinas
2021-03-18 17:12         ` Mark Rutland
2021-03-18 17:12           ` Mark Rutland
2021-03-18 18:36           ` Catalin Marinas
2021-03-18 18:36             ` Catalin Marinas
2021-03-17 22:23 ` [PATCH 0/2] Fix page_owner broken on arm64 Andrew Morton
2021-03-17 22:23   ` Andrew Morton

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