As of now if CONFIG_FUNCTION_GRAPH_TRACER is disabled some functions
like gic_handle_irq will not be added in irqentry text section.
which leads to adding more stacks in stackdepot as frames below IRQ
will not be filtered with filter_irq_stack() function.
checked with debug interface for satckdepot:
https://lkml.org/lkml/2017/11/22/242
e.g. (ARM)
stack count 23188 backtrace
prep_new_page+0x14c/0x160
get_page_from_freelist+0x1258/0x1350
...
__handle_domain_irq+0x1ac/0x4ac
gic_handle_irq+0x44/0x80
__irq_svc+0x5c/0x98
__slab_alloc.constprop.0+0x84/0xac
__kmalloc+0x31c/0x340
sf_malloc+0x14/0x18
and for same _irq_svc there were 25000 calls which was causing
memory pressure of 2MB more on satckdepot, which will keep increasing.
Before patch memory consumption on ARM target after 2 hours:
Memory consumed by Stackdepot:3600 KB
After change:
============
Memory consumed by Stackdepot:1744 KB
prep_new_page+0x14c/0x160
get_page_from_freelist+0x2e4/0x1350
...
__handle_domain_irq+0x1ac/0x4ac
gic_handle_irq+0x44/0x80
^^^^^ no frames below this.
Signed-off-by: Maninder Singh <[email protected]>
Signed-off-by: Vaneet Narang <[email protected]>
---
arch/arm/include/asm/exception.h | 2 +-
arch/arm64/include/asm/exception.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm/include/asm/exception.h b/arch/arm/include/asm/exception.h
index 58e039a851af..3f4534cccc0f 100644
--- a/arch/arm/include/asm/exception.h
+++ b/arch/arm/include/asm/exception.h
@@ -10,7 +10,7 @@
#include <linux/interrupt.h>
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_STACKDEPOT)
#define __exception_irq_entry __irq_entry
#else
#define __exception_irq_entry
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 339477dca551..ef2581b63405 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -13,7 +13,7 @@
#include <linux/interrupt.h>
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_STACKDEPOT)
#define __exception_irq_entry __irq_entry
#else
#define __exception_irq_entry __kprobes
--
2.17.1
Hi,
Any inputs on this?
>As of now if CONFIG_FUNCTION_GRAPH_TRACER is disabled some functions
>like gic_handle_irq will not be added in irqentry text section.
>
>which leads to adding more stacks in stackdepot as frames below IRQ
>will not be filtered with filter_irq_stack() function.
>
>checked with debug interface for satckdepot:
>https://lkml.org/lkml/2017/11/22/242
>
>e.g. (ARM)
>stack count 23188 backtrace
> prep_new_page+0x14c/0x160
> get_page_from_freelist+0x1258/0x1350
>...
> __handle_domain_irq+0x1ac/0x4ac
> gic_handle_irq+0x44/0x80
> __irq_svc+0x5c/0x98
> __slab_alloc.constprop.0+0x84/0xac
> __kmalloc+0x31c/0x340
> sf_malloc+0x14/0x18
>
>and for same _irq_svc there were 25000 calls which was causing
>memory pressure of 2MB more on satckdepot, which will keep increasing.
>
>Before patch memory consumption on ARM target after 2 hours:
>Memory consumed by Stackdepot:3600 KB
>
>After change:
>============
>Memory consumed by Stackdepot:1744 KB
>
> prep_new_page+0x14c/0x160
> get_page_from_freelist+0x2e4/0x1350
>...
> __handle_domain_irq+0x1ac/0x4ac
> gic_handle_irq+0x44/0x80
>
>^^^^^ no frames below this.
>
>Signed-off-by: Maninder Singh <[email protected]>
>Signed-off-by: Vaneet Narang <[email protected]>
>---
> arch/arm/include/asm/exception.h | 2 +-
> arch/arm64/include/asm/exception.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/arch/arm/include/asm/exception.h b/arch/arm/include/asm/exception.h
>index 58e039a851af..3f4534cccc0f 100644
>--- a/arch/arm/include/asm/exception.h
>+++ b/arch/arm/include/asm/exception.h
>@@ -10,7 +10,7 @@
>
> #include <linux/interrupt.h>
>
>-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>+#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_STACKDEPOT)
> #define __exception_irq_entry __irq_entry
> #else
> #define __exception_irq_entry
>diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
>index 339477dca551..ef2581b63405 100644
>--- a/arch/arm64/include/asm/exception.h
>+++ b/arch/arm64/include/asm/exception.h
>@@ -13,7 +13,7 @@
>
> #include <linux/interrupt.h>
>
>-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>+#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_STACKDEPOT)
> #define __exception_irq_entry __irq_entry
> #else
> #define __exception_irq_entry __kprobes
>--
On Mon, Sep 06, 2021 at 06:13:51PM +0530, Maninder Singh wrote:
>
> Hi,
>
> Any inputs on this?
No, I've not heard of stackdepot, I don't know what it is, or what
it does. It doesn't appear to be documented in Documentation - case
insensitive grep for "stackdepot" gets no hits. No help text on its
Kconfig option.
How are arch maintainers supposed to know anything about this?
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
Hi,
>No, I've not heard of stackdepot, I don't know what it is, or what
>it does. It doesn't appear to be documented in Documentation - case
>insensitive grep for "stackdepot" gets no hits. No help text on its
>Kconfig option.
>
>How are arch maintainers supposed to know anything about this?
ok.
Added reviewers/maintainers of stackdepot and KASAN(filter_irq_stack) code.
Because on our ARM H/W it was causing memory issue, and without this change
purpose of filter_irq_stack was gone as it was not filtering irq stacks.
If anyone else has any views or comments for this.
Thanks
Maninder Singh