Currently arm64 supports per-CPU IRQ stack, but softirqs
are still handled in the task context.
Since any call to local_bh_enable() at any level in the task's
call stack may trigger a softirq processing run, which could
potentially cause a task stack overflow if the combined stack
footprints exceed the stack's size, let's run these softirqs
on the IRQ stack as well.
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Acked-by: Will Deacon <[email protected]>
---
v1: https://lore.kernel.org/lkml/[email protected]/
RFC: https://lore.kernel.org/lkml/[email protected]/
Changelog in v1 -> v2:
- temporarily discard [PATCH v1 2/2] to allow this patch to be merged first
- rebase onto the v5.19
- collect Reviewed-by and Acked-by
Changelog in RFC -> v1:
- fix conflicts with commit f2c5092190f2 ("arch/*: Disable softirq stacks on PREEMPT_RT.")
arch/arm64/Kconfig | 1 +
arch/arm64/kernel/irq.c | 13 +++++++++++++
2 files changed, 14 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1652a9800ebe..90f1ab403724 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -226,6 +226,7 @@ config ARM64
select THREAD_INFO_IN_TASK
select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD
select TRACE_IRQFLAGS_SUPPORT
+ select HAVE_SOFTIRQ_ON_OWN_STACK
help
ARM 64-bit (AArch64) Linux support.
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index bda49430c9ea..c36ad20a52f3 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -22,6 +22,7 @@
#include <linux/vmalloc.h>
#include <asm/daifflags.h>
#include <asm/vmap_stack.h>
+#include <asm/exception.h>
/* Only access this in an NMI enter/exit */
DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts);
@@ -71,6 +72,18 @@ static void init_irq_stacks(void)
}
#endif
+#ifndef CONFIG_PREEMPT_RT
+static void ____do_softirq(struct pt_regs *regs)
+{
+ __do_softirq();
+}
+
+void do_softirq_own_stack(void)
+{
+ call_on_irq_stack(NULL, ____do_softirq);
+}
+#endif
+
static void default_handle_irq(struct pt_regs *regs)
{
panic("IRQ taken without a root IRQ handler\n");
--
2.20.1
On 2022/8/2 14:53, Qi Zheng wrote:
> Currently arm64 supports per-CPU IRQ stack, but softirqs
> are still handled in the task context.
>
> Since any call to local_bh_enable() at any level in the task's
> call stack may trigger a softirq processing run, which could
> potentially cause a task stack overflow if the combined stack
> footprints exceed the stack's size, let's run these softirqs
> on the IRQ stack as well.
>
> Signed-off-by: Qi Zheng <[email protected]>
> Reviewed-by: Arnd Bergmann <[email protected]>
> Acked-by: Will Deacon <[email protected]>
Hi Will,
Are we good to merge it into 6.0-rc1?
Thanks,
Qi
> ---
> v1: https://lore.kernel.org/lkml/[email protected]/
> RFC: https://lore.kernel.org/lkml/[email protected]/
>
> Changelog in v1 -> v2:
> - temporarily discard [PATCH v1 2/2] to allow this patch to be merged first
> - rebase onto the v5.19
> - collect Reviewed-by and Acked-by
>
> Changelog in RFC -> v1:
> - fix conflicts with commit f2c5092190f2 ("arch/*: Disable softirq stacks on PREEMPT_RT.")
>
> arch/arm64/Kconfig | 1 +
> arch/arm64/kernel/irq.c | 13 +++++++++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1652a9800ebe..90f1ab403724 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -226,6 +226,7 @@ config ARM64
> select THREAD_INFO_IN_TASK
> select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD
> select TRACE_IRQFLAGS_SUPPORT
> + select HAVE_SOFTIRQ_ON_OWN_STACK
> help
> ARM 64-bit (AArch64) Linux support.
>
> diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
> index bda49430c9ea..c36ad20a52f3 100644
> --- a/arch/arm64/kernel/irq.c
> +++ b/arch/arm64/kernel/irq.c
> @@ -22,6 +22,7 @@
> #include <linux/vmalloc.h>
> #include <asm/daifflags.h>
> #include <asm/vmap_stack.h>
> +#include <asm/exception.h>
>
> /* Only access this in an NMI enter/exit */
> DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts);
> @@ -71,6 +72,18 @@ static void init_irq_stacks(void)
> }
> #endif
>
> +#ifndef CONFIG_PREEMPT_RT
> +static void ____do_softirq(struct pt_regs *regs)
> +{
> + __do_softirq();
> +}
> +
> +void do_softirq_own_stack(void)
> +{
> + call_on_irq_stack(NULL, ____do_softirq);
> +}
> +#endif
> +
> static void default_handle_irq(struct pt_regs *regs)
> {
> panic("IRQ taken without a root IRQ handler\n");
--
Thanks,
Qi
On 2022/8/5 15:50, Arnd Bergmann wrote:
> On Fri, Aug 5, 2022 at 9:10 AM Qi Zheng <[email protected]> wrote:
>> On 2022/8/2 14:53, Qi Zheng wrote:
>>> Currently arm64 supports per-CPU IRQ stack, but softirqs
>>> are still handled in the task context.
>>>
>>> Since any call to local_bh_enable() at any level in the task's
>>> call stack may trigger a softirq processing run, which could
>>> potentially cause a task stack overflow if the combined stack
>>> footprints exceed the stack's size, let's run these softirqs
>>> on the IRQ stack as well.
>>>
>>> Signed-off-by: Qi Zheng <[email protected]>
>>> Reviewed-by: Arnd Bergmann <[email protected]>
>>> Acked-by: Will Deacon <[email protected]>
>>
>> Are we good to merge it into 6.0-rc1?
>
> I think you misunderstood the timing that Will proposed in
>
> https://lore.kernel.org/linux-arm-kernel/[email protected]/
>
> You should send your patch after 6.0-rc1 has been released, to be merged
> into the linux-next tree and sent as part of the 6.1 merge window.
Oh, got it. I will repost it after 6.0-rc1.
>
> The two ways patches get merged are:
>
> - bugfixes can get merged into maintainer trees at any time and sent
> upstream regardless of the merge window, these never need to wait
>
> - non-bugfix patches can get merged into maintainer trees based on an
> -rc release and then sent upstream during the following merge window.
Thanks for such detailed information. :)
>
> Arnd
Thanks,
Qi
--
Thanks,
Qi
On Fri, Aug 5, 2022 at 9:10 AM Qi Zheng <[email protected]> wrote:
> On 2022/8/2 14:53, Qi Zheng wrote:
> > Currently arm64 supports per-CPU IRQ stack, but softirqs
> > are still handled in the task context.
> >
> > Since any call to local_bh_enable() at any level in the task's
> > call stack may trigger a softirq processing run, which could
> > potentially cause a task stack overflow if the combined stack
> > footprints exceed the stack's size, let's run these softirqs
> > on the IRQ stack as well.
> >
> > Signed-off-by: Qi Zheng <[email protected]>
> > Reviewed-by: Arnd Bergmann <[email protected]>
> > Acked-by: Will Deacon <[email protected]>
>
> Are we good to merge it into 6.0-rc1?
I think you misunderstood the timing that Will proposed in
https://lore.kernel.org/linux-arm-kernel/[email protected]/
You should send your patch after 6.0-rc1 has been released, to be merged
into the linux-next tree and sent as part of the 6.1 merge window.
The two ways patches get merged are:
- bugfixes can get merged into maintainer trees at any time and sent
upstream regardless of the merge window, these never need to wait
- non-bugfix patches can get merged into maintainer trees based on an
-rc release and then sent upstream during the following merge window.
Arnd
Hi Qi,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on soc/for-next]
[also build test WARNING on v5.19]
[cannot apply to arm64/for-next/core linus/master next-20220805]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Qi-Zheng/arm64-run-softirqs-on-the-per-CPU-IRQ-stack/20220802-145547
base: https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: arm64-randconfig-r032-20220801 (https://download.01.org/0day-ci/archive/20220807/[email protected]/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 52cd00cabf479aa7eb6dbb063b7ba41ea57bce9e)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/34ac9375ce5e75127084159f724fcb2208c022a3
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Qi-Zheng/arm64-run-softirqs-on-the-per-CPU-IRQ-stack/20220802-145547
git checkout 34ac9375ce5e75127084159f724fcb2208c022a3
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash arch/arm64/kernel/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
>> arch/arm64/kernel/irq.c:81:6: warning: no previous prototype for function 'do_softirq_own_stack' [-Wmissing-prototypes]
void do_softirq_own_stack(void)
^
arch/arm64/kernel/irq.c:81:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
void do_softirq_own_stack(void)
^
static
arch/arm64/kernel/irq.c:120:13: warning: no previous prototype for function 'init_IRQ' [-Wmissing-prototypes]
void __init init_IRQ(void)
^
arch/arm64/kernel/irq.c:120:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
void __init init_IRQ(void)
^
static
2 warnings generated.
vim +/do_softirq_own_stack +81 arch/arm64/kernel/irq.c
80
> 81 void do_softirq_own_stack(void)
82 {
83 call_on_irq_stack(NULL, ____do_softirq);
84 }
85 #endif
86
--
0-DAY CI Kernel Test Service
https://01.org/lkp
Hi Qi,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on soc/for-next]
[also build test WARNING on v5.19]
[cannot apply to arm64/for-next/core linus/master next-20220805]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Qi-Zheng/arm64-run-softirqs-on-the-per-CPU-IRQ-stack/20220802-145547
base: https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: arm64-randconfig-r024-20220801 (https://download.01.org/0day-ci/archive/20220807/[email protected]/config)
compiler: aarch64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/34ac9375ce5e75127084159f724fcb2208c022a3
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Qi-Zheng/arm64-run-softirqs-on-the-per-CPU-IRQ-stack/20220802-145547
git checkout 34ac9375ce5e75127084159f724fcb2208c022a3
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash arch/arm64/kernel/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
>> arch/arm64/kernel/irq.c:81:6: warning: no previous prototype for 'do_softirq_own_stack' [-Wmissing-prototypes]
81 | void do_softirq_own_stack(void)
| ^~~~~~~~~~~~~~~~~~~~
arch/arm64/kernel/irq.c:120:13: warning: no previous prototype for 'init_IRQ' [-Wmissing-prototypes]
120 | void __init init_IRQ(void)
| ^~~~~~~~
vim +/do_softirq_own_stack +81 arch/arm64/kernel/irq.c
80
> 81 void do_softirq_own_stack(void)
82 {
83 call_on_irq_stack(NULL, ____do_softirq);
84 }
85 #endif
86
--
0-DAY CI Kernel Test Service
https://01.org/lkp