[PATCH 0/3] kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

[PATCH 0/3] kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

[Baoquan He]

Ignat reported a potential config regression was introduced by
commit 89cde455915f ("kexec: consolidate kexec and crash options
into kernel/Kconfig.kexec"). Please click below link for more details:

https://lore.kernel.org/all/CALrw=nHpRQQaQTP_jZfREgrQEMpS8jBF8JQCv4ygqXycE-StaA@mail.gmail.com/T/#u

The patch 1 fix the regression by removing incorrect CONFIG_KEXEC
ifdeffery scope adding in arm's <asm/kexec.h>, then dropping the
select of KEXEC for CRASH_DUMP. This is tested and passed a cross
comiping of arm.

Patch 2 is to fix a build failure when I tested patch 1 on x86_64, the
wrong CONFIG_KEXEC iddeffery is replaced with CONFIG_KEXEC_CORE. Test
passed on x86_64.

Patch 3 is to fix an unnecessary 'select KEXEC' in s390 ARCH. Removing
the select won't impact anything. Test passed on a ibm-z system.

Baoquan He (3):
  kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP
  drivers/base/cpu: crash data showing should depends on KEXEC_CORE
  s390/Kconfig: drop select of KEXEC

 arch/arm/include/asm/kexec.h | 4 ----
 arch/s390/Kconfig            | 1 -
 drivers/base/cpu.c           | 6 +++---
 kernel/Kconfig.kexec         | 1 -
 4 files changed, 3 insertions(+), 9 deletions(-)

-- 
2.41.0

[PATCH 1/3] kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

[Baoquan He]

Ignat Korchagin complained that a potential config regression was
introduced by commit 89cde455915f ("kexec: consolidate kexec and
crash options into kernel/Kconfig.kexec"). Before the commit,
CONFIG_CRASH_DUMP has no dependency on CONFIG_KEXEC. After the commit,
CRASH_DUMP selects KEXEC. That enforces system to have CONFIG_KEXEC=y
as long as CONFIG_CRASH_DUMP=Y which people may not want.

In Ignat's case, he sets CONFIG_CRASH_DUMP=y, CONFIG_KEXEC_FILE=y and
CONFIG_KEXEC=n because kexec_load interface could have security issue if
kernel/initrd has no chance to be signed and verified.

CRASH_DUMP has select of KEXEC because Eric, author of above commit,
met a LKP report of build failure when posting patch of earlier version.
Please see below link to get detail of the LKP report:

    https://lore.kernel.org/all/3e8eecd1-a277-2cfb-690e-5de2eb7b988e@oracle.com/T/#u

In fact, that LKP report is triggered because arm's <asm/kexec.h> is
wrapped in CONFIG_KEXEC ifdeffery scope. That is wrong. CONFIG_KEXEC
controls the enabling/disabling of kexec_load interface, but not kexec
feature. Removing the wrongly added CONFIG_KEXEC ifdeffery scope in
<asm/kexec.h> of arm allows us to drop the select KEXEC for CRASH_DUMP.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/arm/include/asm/kexec.h | 4 ----
 kernel/Kconfig.kexec         | 1 -
 2 files changed, 5 deletions(-)

diff --git a/arch/arm/include/asm/kexec.h b/arch/arm/include/asm/kexec.h
index e62832dcba76..a8287e7ab9d4 100644
--- a/arch/arm/include/asm/kexec.h
+++ b/arch/arm/include/asm/kexec.h
@@ -2,8 +2,6 @@
 #ifndef _ARM_KEXEC_H
 #define _ARM_KEXEC_H
 
-#ifdef CONFIG_KEXEC
-
 /* Maximum physical address we can use pages from */
 #define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
 /* Maximum address we can reach in physical address mode */
@@ -82,6 +80,4 @@ static inline struct page *boot_pfn_to_page(unsigned long boot_pfn)
 
 #endif /* __ASSEMBLY__ */
 
-#endif /* CONFIG_KEXEC */
-
 #endif /* _ARM_KEXEC_H */
diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
index 7aff28ded2f4..1cc3b1c595d7 100644
--- a/kernel/Kconfig.kexec
+++ b/kernel/Kconfig.kexec
@@ -97,7 +97,6 @@ config CRASH_DUMP
 	depends on ARCH_SUPPORTS_KEXEC
 	select CRASH_CORE
 	select KEXEC_CORE
-	select KEXEC
 	help
 	  Generate crash dump after being started by kexec.
 	  This should be normally only set in special crash dump kernels
-- 
2.41.0

[PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Baoquan He]

When below kernel config items are set, compiling error are triggered.

CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
CONFIG_CRASH_HOTPLUG=y

------------------------------------------------------
drivers/base/cpu.c: In function ‘crash_hotplug_show’:
drivers/base/cpu.c:309:40: error: implicit declaration of function ‘crash_hotplug_cpu_support’; did you mean ‘crash_hotplug_show’? [-Werror=implicit-function-declaration]
  309 |         return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support());
      |                                        ^~~~~~~~~~~~~~~~~~~~~~~~~
      |                                        crash_hotplug_show
cc1: some warnings being treated as errors
------------------------------------------------------

CONFIG_KEXEC is used to enable kexec_load interface, the
crash_notes/crash_notes_size/crash_hotplug showing depends on
CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.

Fix it now.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 drivers/base/cpu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 9ea22e165acd..548491de818e 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -144,7 +144,7 @@ static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 #endif /* CONFIG_HOTPLUG_CPU */
 
-#ifdef CONFIG_KEXEC
+#ifdef CONFIG_KEXEC_CORE
 #include <linux/kexec.h>
 
 static ssize_t crash_notes_show(struct device *dev,
@@ -189,14 +189,14 @@ static const struct attribute_group crash_note_cpu_attr_group = {
 #endif
 
 static const struct attribute_group *common_cpu_attr_groups[] = {
-#ifdef CONFIG_KEXEC
+#ifdef CONFIG_KEXEC_CORE
 	&crash_note_cpu_attr_group,
 #endif
 	NULL
 };
 
 static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
-#ifdef CONFIG_KEXEC
+#ifdef CONFIG_KEXEC_CORE
 	&crash_note_cpu_attr_group,
 #endif
 	NULL
-- 
2.41.0

[PATCH 3/3] s390/Kconfig: drop select of KEXEC

[Baoquan He]

No proof is found to require that S390 architecture has to select
KEXEC. At least from my testing at below, dropping select of KEXEC won't
impact anything.

===testing 1===
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
===

===testing 2===
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC_FILE=y
CONFIG_CRASH_DUMP=y
===

So drop the select of KEXEC now.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/s390/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3bec98d20283..1aec2e692dca 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -217,7 +217,6 @@ config S390
 	select HAVE_VIRT_CPU_ACCOUNTING_IDLE
 	select IOMMU_HELPER		if PCI
 	select IOMMU_SUPPORT		if PCI
-	select KEXEC
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_GATHER_NO_GATHER
 	select MMU_GATHER_RCU_TABLE_FREE
-- 
2.41.0

Re: [PATCH 1/3] kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

[Ignat Korchagin]

On Thu, Nov 23, 2023 at 7:37 AM Baoquan He <bhe@redhat.com> wrote:
>
> Ignat Korchagin complained that a potential config regression was
> introduced by commit 89cde455915f ("kexec: consolidate kexec and
> crash options into kernel/Kconfig.kexec"). Before the commit,
> CONFIG_CRASH_DUMP has no dependency on CONFIG_KEXEC. After the commit,
> CRASH_DUMP selects KEXEC. That enforces system to have CONFIG_KEXEC=y
> as long as CONFIG_CRASH_DUMP=Y which people may not want.
>
> In Ignat's case, he sets CONFIG_CRASH_DUMP=y, CONFIG_KEXEC_FILE=y and
> CONFIG_KEXEC=n because kexec_load interface could have security issue if
> kernel/initrd has no chance to be signed and verified.
>
> CRASH_DUMP has select of KEXEC because Eric, author of above commit,
> met a LKP report of build failure when posting patch of earlier version.
> Please see below link to get detail of the LKP report:
>
>     https://lore.kernel.org/all/3e8eecd1-a277-2cfb-690e-5de2eb7b988e@oracle.com/T/#u
>
> In fact, that LKP report is triggered because arm's <asm/kexec.h> is
> wrapped in CONFIG_KEXEC ifdeffery scope. That is wrong. CONFIG_KEXEC
> controls the enabling/disabling of kexec_load interface, but not kexec
> feature. Removing the wrongly added CONFIG_KEXEC ifdeffery scope in
> <asm/kexec.h> of arm allows us to drop the select KEXEC for CRASH_DUMP.

Hm... With the patch, when cross compiling for arm and
CONFIG_KEXEC_CORE=y
# CONFIG_KEXEC is not set
CONFIG_CRASH_DUMP=y

I get the following linker error at the end:

  CALL    scripts/checksyscalls.sh
  UPD     include/generated/utsversion.h
  CC      init/version-timestamp.o
  LD      .tmp_vmlinux.kallsyms1
arm-linux-gnueabi-ld: kernel/kexec_core.o: in function `kimage_free':
kexec_core.c:(.text+0xf5c): undefined reference to `machine_kexec_cleanup'
arm-linux-gnueabi-ld: kernel/kexec_core.o: in function `__crash_kexec':
kexec_core.c:(.text+0x15bc): undefined reference to `machine_crash_shutdown'
arm-linux-gnueabi-ld: kexec_core.c:(.text+0x15c4): undefined reference
to `machine_kexec'
arm-linux-gnueabi-ld: kernel/kexec_core.o: in function `kernel_kexec':
kexec_core.c:(.text+0x1a04): undefined reference to `machine_kexec'
make[2]: *** [scripts/Makefile.vmlinux:37: vmlinux] Error 1
make[1]: *** [/home/ignat/git/linux-upstream/Makefile:1154: vmlinux] Error 2
make: *** [Makefile:234: __sub-make] Error 2

> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  arch/arm/include/asm/kexec.h | 4 ----
>  kernel/Kconfig.kexec         | 1 -
>  2 files changed, 5 deletions(-)
>
> diff --git a/arch/arm/include/asm/kexec.h b/arch/arm/include/asm/kexec.h
> index e62832dcba76..a8287e7ab9d4 100644
> --- a/arch/arm/include/asm/kexec.h
> +++ b/arch/arm/include/asm/kexec.h
> @@ -2,8 +2,6 @@
>  #ifndef _ARM_KEXEC_H
>  #define _ARM_KEXEC_H
>
> -#ifdef CONFIG_KEXEC
> -
>  /* Maximum physical address we can use pages from */
>  #define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
>  /* Maximum address we can reach in physical address mode */
> @@ -82,6 +80,4 @@ static inline struct page *boot_pfn_to_page(unsigned long boot_pfn)
>
>  #endif /* __ASSEMBLY__ */
>
> -#endif /* CONFIG_KEXEC */
> -
>  #endif /* _ARM_KEXEC_H */
> diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
> index 7aff28ded2f4..1cc3b1c595d7 100644
> --- a/kernel/Kconfig.kexec
> +++ b/kernel/Kconfig.kexec
> @@ -97,7 +97,6 @@ config CRASH_DUMP
>         depends on ARCH_SUPPORTS_KEXEC
>         select CRASH_CORE
>         select KEXEC_CORE
> -       select KEXEC
>         help
>           Generate crash dump after being started by kexec.
>           This should be normally only set in special crash dump kernels
> --
> 2.41.0
>

Re: [PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Ignat Korchagin]

On Thu, Nov 23, 2023 at 7:37 AM Baoquan He <bhe@redhat.com> wrote:
>
> When below kernel config items are set, compiling error are triggered.
>
> CONFIG_CRASH_CORE=y
> CONFIG_KEXEC_CORE=y
> CONFIG_CRASH_DUMP=y
> CONFIG_CRASH_HOTPLUG=y
>
> ------------------------------------------------------
> drivers/base/cpu.c: In function ‘crash_hotplug_show’:
> drivers/base/cpu.c:309:40: error: implicit declaration of function ‘crash_hotplug_cpu_support’; did you mean ‘crash_hotplug_show’? [-Werror=implicit-function-declaration]
>   309 |         return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support());
>       |                                        ^~~~~~~~~~~~~~~~~~~~~~~~~
>       |                                        crash_hotplug_show
> cc1: some warnings being treated as errors
> ------------------------------------------------------
>
> CONFIG_KEXEC is used to enable kexec_load interface, the
> crash_notes/crash_notes_size/crash_hotplug showing depends on
> CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.
>
> Fix it now.

Can we add Fixes/CC stable, so it gets eventually backported into 6.6?

> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  drivers/base/cpu.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 9ea22e165acd..548491de818e 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -144,7 +144,7 @@ static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
>  #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
>  #endif /* CONFIG_HOTPLUG_CPU */
>
> -#ifdef CONFIG_KEXEC
> +#ifdef CONFIG_KEXEC_CORE
>  #include <linux/kexec.h>
>
>  static ssize_t crash_notes_show(struct device *dev,
> @@ -189,14 +189,14 @@ static const struct attribute_group crash_note_cpu_attr_group = {
>  #endif
>
>  static const struct attribute_group *common_cpu_attr_groups[] = {
> -#ifdef CONFIG_KEXEC
> +#ifdef CONFIG_KEXEC_CORE
>         &crash_note_cpu_attr_group,
>  #endif
>         NULL
>  };
>
>  static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
> -#ifdef CONFIG_KEXEC
> +#ifdef CONFIG_KEXEC_CORE
>         &crash_note_cpu_attr_group,
>  #endif
>         NULL
> --
> 2.41.0
>

Re: [PATCH 1/3] kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

[Baoquan He]

On 11/23/23 at 08:23am, Ignat Korchagin wrote:
> On Thu, Nov 23, 2023 at 7:37 AM Baoquan He <bhe@redhat.com> wrote:
> >
> > Ignat Korchagin complained that a potential config regression was
> > introduced by commit 89cde455915f ("kexec: consolidate kexec and
> > crash options into kernel/Kconfig.kexec"). Before the commit,
> > CONFIG_CRASH_DUMP has no dependency on CONFIG_KEXEC. After the commit,
> > CRASH_DUMP selects KEXEC. That enforces system to have CONFIG_KEXEC=y
> > as long as CONFIG_CRASH_DUMP=Y which people may not want.
> >
> > In Ignat's case, he sets CONFIG_CRASH_DUMP=y, CONFIG_KEXEC_FILE=y and
> > CONFIG_KEXEC=n because kexec_load interface could have security issue if
> > kernel/initrd has no chance to be signed and verified.
> >
> > CRASH_DUMP has select of KEXEC because Eric, author of above commit,
> > met a LKP report of build failure when posting patch of earlier version.
> > Please see below link to get detail of the LKP report:
> >
> >     https://lore.kernel.org/all/3e8eecd1-a277-2cfb-690e-5de2eb7b988e@oracle.com/T/#u
> >
> > In fact, that LKP report is triggered because arm's <asm/kexec.h> is
> > wrapped in CONFIG_KEXEC ifdeffery scope. That is wrong. CONFIG_KEXEC
> > controls the enabling/disabling of kexec_load interface, but not kexec
> > feature. Removing the wrongly added CONFIG_KEXEC ifdeffery scope in
> > <asm/kexec.h> of arm allows us to drop the select KEXEC for CRASH_DUMP.
> 
> Hm... With the patch, when cross compiling for arm and
> CONFIG_KEXEC_CORE=y
> # CONFIG_KEXEC is not set
> CONFIG_CRASH_DUMP=y
> 
> I get the following linker error at the end:
> 
>   CALL    scripts/checksyscalls.sh
>   UPD     include/generated/utsversion.h
>   CC      init/version-timestamp.o
>   LD      .tmp_vmlinux.kallsyms1
> arm-linux-gnueabi-ld: kernel/kexec_core.o: in function `kimage_free':
> kexec_core.c:(.text+0xf5c): undefined reference to `machine_kexec_cleanup'
> arm-linux-gnueabi-ld: kernel/kexec_core.o: in function `__crash_kexec':
> kexec_core.c:(.text+0x15bc): undefined reference to `machine_crash_shutdown'
> arm-linux-gnueabi-ld: kexec_core.c:(.text+0x15c4): undefined reference
> to `machine_kexec'
> arm-linux-gnueabi-ld: kernel/kexec_core.o: in function `kernel_kexec':
> kexec_core.c:(.text+0x1a04): undefined reference to `machine_kexec'
> make[2]: *** [scripts/Makefile.vmlinux:37: vmlinux] Error 1
> make[1]: *** [/home/ignat/git/linux-upstream/Makefile:1154: vmlinux] Error 2
> make: *** [Makefile:234: __sub-make] Error 2

Oops, I forgot this part. This should fix the link error.

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index d53f56d6f840..771264d4726a 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -59,7 +59,7 @@ obj-$(CONFIG_FUNCTION_TRACER)	+= entry-ftrace.o
 obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o insn.o patch.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o insn.o patch.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o insn.o patch.o
-obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_KEXEC_CORE)	+= machine_kexec.o relocate_kernel.o
 # Main staffs in KPROBES are in arch/arm/probes/ .
 obj-$(CONFIG_KPROBES)		+= patch.o insn.o
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o

Re: [PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Baoquan He]

On 11/23/23 at 08:34am, Ignat Korchagin wrote:
> On Thu, Nov 23, 2023 at 7:37 AM Baoquan He <bhe@redhat.com> wrote:
> >
> > When below kernel config items are set, compiling error are triggered.
> >
> > CONFIG_CRASH_CORE=y
> > CONFIG_KEXEC_CORE=y
> > CONFIG_CRASH_DUMP=y
> > CONFIG_CRASH_HOTPLUG=y
> >
> > ------------------------------------------------------
> > drivers/base/cpu.c: In function ‘crash_hotplug_show’:
> > drivers/base/cpu.c:309:40: error: implicit declaration of function ‘crash_hotplug_cpu_support’; did you mean ‘crash_hotplug_show’? [-Werror=implicit-function-declaration]
> >   309 |         return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support());
> >       |                                        ^~~~~~~~~~~~~~~~~~~~~~~~~
> >       |                                        crash_hotplug_show
> > cc1: some warnings being treated as errors
> > ------------------------------------------------------
> >
> > CONFIG_KEXEC is used to enable kexec_load interface, the
> > crash_notes/crash_notes_size/crash_hotplug showing depends on
> > CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.
> >
> > Fix it now.
> 
> Can we add Fixes/CC stable, so it gets eventually backported into 6.6?

Makes sense. Will add it in v2 since I need respin to add the missing
stuff in patch 1. Thanks.

> 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  drivers/base/cpu.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> > index 9ea22e165acd..548491de818e 100644
> > --- a/drivers/base/cpu.c
> > +++ b/drivers/base/cpu.c
> > @@ -144,7 +144,7 @@ static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
> >  #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
> >  #endif /* CONFIG_HOTPLUG_CPU */
> >
> > -#ifdef CONFIG_KEXEC
> > +#ifdef CONFIG_KEXEC_CORE
> >  #include <linux/kexec.h>
> >
> >  static ssize_t crash_notes_show(struct device *dev,
> > @@ -189,14 +189,14 @@ static const struct attribute_group crash_note_cpu_attr_group = {
> >  #endif
> >
> >  static const struct attribute_group *common_cpu_attr_groups[] = {
> > -#ifdef CONFIG_KEXEC
> > +#ifdef CONFIG_KEXEC_CORE
> >         &crash_note_cpu_attr_group,
> >  #endif
> >         NULL
> >  };
> >
> >  static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
> > -#ifdef CONFIG_KEXEC
> > +#ifdef CONFIG_KEXEC_CORE
> >         &crash_note_cpu_attr_group,
> >  #endif
> >         NULL
> > --
> > 2.41.0
> >
> 

Re: [PATCH 3/3] s390/Kconfig: drop select of KEXEC

[Alexander Gordeev]

On Thu, Nov 23, 2023 at 03:36:52PM +0800, Baoquan He wrote:

Hi Baoquan,

> No proof is found to require that S390 architecture has to select
> KEXEC. At least from my testing at below, dropping select of KEXEC won't
> impact anything.

It does impact the outcome of defconfigs.
Namely, CONFIG_KEXEC is not set with this patch.

> ===testing 1===
> CONFIG_CRASH_CORE=y
> CONFIG_KEXEC_CORE=y
> CONFIG_CRASH_DUMP=y
> ===
> 
> ===testing 2===
> CONFIG_CRASH_CORE=y
> CONFIG_KEXEC_CORE=y
> CONFIG_KEXEC_FILE=y
> CONFIG_CRASH_DUMP=y
> ===

Unfortunately, I do not quite realize what these testings were
and what is the difference between the two.

> So drop the select of KEXEC now.

I suggest dropping this patch. Once the previous two are upstream
we would remove 'select KEXEC' from Kconfig together with defconfig
updates.

> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  arch/s390/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 3bec98d20283..1aec2e692dca 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -217,7 +217,6 @@ config S390
>  	select HAVE_VIRT_CPU_ACCOUNTING_IDLE
>  	select IOMMU_HELPER		if PCI
>  	select IOMMU_SUPPORT		if PCI
> -	select KEXEC
>  	select MMU_GATHER_MERGE_VMAS
>  	select MMU_GATHER_NO_GATHER
>  	select MMU_GATHER_RCU_TABLE_FREE
> -- 

Thanks!

Re: [PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Alexander Gordeev]

On Thu, Nov 23, 2023 at 03:36:51PM +0800, Baoquan He wrote:
> When below kernel config items are set, compiling error are triggered.
> 
> CONFIG_CRASH_CORE=y
> CONFIG_KEXEC_CORE=y
> CONFIG_CRASH_DUMP=y
> CONFIG_CRASH_HOTPLUG=y
> 
> ------------------------------------------------------
> drivers/base/cpu.c: In function ‘crash_hotplug_show’:
> drivers/base/cpu.c:309:40: error: implicit declaration of function ‘crash_hotplug_cpu_support’; did you mean ‘crash_hotplug_show’? [-Werror=implicit-function-declaration]
>   309 |         return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support());
>       |                                        ^~~~~~~~~~~~~~~~~~~~~~~~~
>       |                                        crash_hotplug_show
> cc1: some warnings being treated as errors
> ------------------------------------------------------
> 
> CONFIG_KEXEC is used to enable kexec_load interface, the
> crash_notes/crash_notes_size/crash_hotplug showing depends on
> CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.
> 
> Fix it now.

If this error introduced with the prevous patch?
If so, the patches need to be swapped I guess.

> Signed-off-by: Baoquan He <bhe@redhat.com>

Re: [PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Baoquan He]

On 11/23/23 at 03:13pm, Alexander Gordeev wrote:
> On Thu, Nov 23, 2023 at 03:36:51PM +0800, Baoquan He wrote:
> > When below kernel config items are set, compiling error are triggered.
> > 
> > CONFIG_CRASH_CORE=y
> > CONFIG_KEXEC_CORE=y
> > CONFIG_CRASH_DUMP=y
> > CONFIG_CRASH_HOTPLUG=y
> > 
> > ------------------------------------------------------
> > drivers/base/cpu.c: In function ‘crash_hotplug_show’:
> > drivers/base/cpu.c:309:40: error: implicit declaration of function ‘crash_hotplug_cpu_support’; did you mean ‘crash_hotplug_show’? [-Werror=implicit-function-declaration]
> >   309 |         return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support());
> >       |                                        ^~~~~~~~~~~~~~~~~~~~~~~~~
> >       |                                        crash_hotplug_show
> > cc1: some warnings being treated as errors
> > ------------------------------------------------------
> > 
> > CONFIG_KEXEC is used to enable kexec_load interface, the
> > crash_notes/crash_notes_size/crash_hotplug showing depends on
> > CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.
> > 
> > Fix it now.
> 
> If this error introduced with the prevous patch?
> If so, the patches need to be swapped I guess.

From the phenomenon, yes. In fact it's the patch 1 which exposes
the wrong ifdeffery. I can shift the order in v2. Thanks.

> 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> 

Re: [PATCH 3/3] s390/Kconfig: drop select of KEXEC

[Baoquan He]

On 11/23/23 at 02:43pm, Alexander Gordeev wrote:
> On Thu, Nov 23, 2023 at 03:36:52PM +0800, Baoquan He wrote:
> 
> Hi Baoquan,
> 
> > No proof is found to require that S390 architecture has to select
> > KEXEC. At least from my testing at below, dropping select of KEXEC won't
> > impact anything.
> 
> It does impact the outcome of defconfigs.
> Namely, CONFIG_KEXEC is not set with this patch.

Right, CONFIG_KEXEC won't be set defaultly with this patch applied.

> 
> > ===testing 1===
> > CONFIG_CRASH_CORE=y
> > CONFIG_KEXEC_CORE=y
> > CONFIG_CRASH_DUMP=y
> > ===
> > 
> > ===testing 2===
> > CONFIG_CRASH_CORE=y
> > CONFIG_KEXEC_CORE=y
> > CONFIG_KEXEC_FILE=y
> > CONFIG_CRASH_DUMP=y
> > ===
> 
> Unfortunately, I do not quite realize what these testings were
> and what is the difference between the two.

Both these two testings have CONFIG_KEXEC=n, and building all passed.
I wound't present their difference, but two cases where no CONFIG_KEXEC
is set and no dependency on CONFIG_KEXEC is seen.

> 
> > So drop the select of KEXEC now.
> 
> I suggest dropping this patch. Once the previous two are upstream
> we would remove 'select KEXEC' from Kconfig together with defconfig
> updates.

I see your concern, will drop this one in v2. Thanks for checking these.

> 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  arch/s390/Kconfig | 1 -
> >  1 file changed, 1 deletion(-)
> > 
> > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> > index 3bec98d20283..1aec2e692dca 100644
> > --- a/arch/s390/Kconfig
> > +++ b/arch/s390/Kconfig
> > @@ -217,7 +217,6 @@ config S390
> >  	select HAVE_VIRT_CPU_ACCOUNTING_IDLE
> >  	select IOMMU_HELPER		if PCI
> >  	select IOMMU_SUPPORT		if PCI
> > -	select KEXEC
> >  	select MMU_GATHER_MERGE_VMAS
> >  	select MMU_GATHER_NO_GATHER
> >  	select MMU_GATHER_RCU_TABLE_FREE
> > -- 
> 
> Thanks!
> 

Re: [PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Andrew Morton]

On Thu, 23 Nov 2023 19:15:43 +0800 Baoquan He <bhe@redhat.com> wrote:

> > > CONFIG_KEXEC is used to enable kexec_load interface, the
> > > crash_notes/crash_notes_size/crash_hotplug showing depends on
> > > CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.
> > >
> > > Fix it now.
> > 
> > Can we add Fixes/CC stable, so it gets eventually backported into 6.6?
> 
> Makes sense. Will add it in v2 since I need respin to add the missing
> stuff in patch 1. Thanks.

Please avoid mixing cc:stable patches and this-merge-window fixes in
the same series as next-merge-window material.  Because I'll just have
to separate them out anyway, causing what-I-merged to unnecessarily
differ from what-you-sent.

Re: [PATCH 2/3] drivers/base/cpu: crash data showing should depends on KEXEC_CORE

[Baoquan He]

On 11/24/23 at 08:44am, Andrew Morton wrote:
> On Thu, 23 Nov 2023 19:15:43 +0800 Baoquan He <bhe@redhat.com> wrote:
> 
> > > > CONFIG_KEXEC is used to enable kexec_load interface, the
> > > > crash_notes/crash_notes_size/crash_hotplug showing depends on
> > > > CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead.
> > > >
> > > > Fix it now.
> > > 
> > > Can we add Fixes/CC stable, so it gets eventually backported into 6.6?
> > 
> > Makes sense. Will add it in v2 since I need respin to add the missing
> > stuff in patch 1. Thanks.
> 
> Please avoid mixing cc:stable patches and this-merge-window fixes in
> the same series as next-merge-window material.  Because I'll just have
> to separate them out anyway, causing what-I-merged to unnecessarily
> differ from what-you-sent.

Got it, will send them separately because the issue that this patch is fixing
has been there for very long time. Thanks for noticing.

Re: [PATCH 0/3] kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

[Baoquan He]

On 11/25/23 at 06:07pm, Eric DeVolder wrote:
> 
> On 11/23/23 01:36, Baoquan He wrote:
> > Ignat reported a potential config regression was introduced by
> > commit 89cde455915f ("kexec: consolidate kexec and crash options
> > into kernel/Kconfig.kexec"). Please click below link for more details:
> > 
> > https://lore.kernel.org/all/CALrw=nHpRQQaQTP_jZfREgrQEMpS8jBF8JQCv4ygqXycE-StaA@mail.gmail.com/T/#u
> > 
> > The patch 1 fix the regression by removing incorrect CONFIG_KEXEC
> > ifdeffery scope adding in arm's <asm/kexec.h>, then dropping the
> > select of KEXEC for CRASH_DUMP. This is tested and passed a cross
> > comiping of arm.
> > 
> > Patch 2 is to fix a build failure when I tested patch 1 on x86_64, the
> > wrong CONFIG_KEXEC iddeffery is replaced with CONFIG_KEXEC_CORE. Test
> > passed on x86_64.
> > 
> > Patch 3 is to fix an unnecessary 'select KEXEC' in s390 ARCH. Removing
> > the select won't impact anything. Test passed on a ibm-z system.
> 
> I apologize for my delay in responding, I did not have a computer with me
> during my holiday travel.
> 
> I was able to re-run my Kconfig test script with this patch series (now that
> I'm running this on private resources, it takes half a day 8( ). The script
> only performs comparisons of the .config before (LHSB) and after (RHSB) the
> patch series; it does NOT do any building. At any rate, what that revealed
> was only differences in s390. That means that all other arches do not have
> any unintended side effects. The differences with patch3 applied look like:
> 
> FAIL: allnoconfig arch/s390/configs/kasan.config
> LHSB {'CONFIG_CRASH_CORE': 'y', 'CONFIG_KEXEC_CORE': 'y', 'CONFIG_KEXEC':
> 'y'}
> RHSB {'CONFIG_KEXEC': 'n'}
> 
> The 'allnoconfig' and 'olddefconfig' targets failed for all s390 defconfigs.
> The LHSB is the pre-patch values, and the RHSB is the post-patch values. So
> this states that CRASH_CORE and KEXEC_CORE were set previously, but now they
> are not. KEXEC obviously is being turned off intentionally.
> 
> Hope this helps some.

Thanks, Eric. Alexander has pointed out this in patch 3 reviewing
comment. I misunderstood the select KEXEC in s390 arch where they
intend to do. As I replied to Alexander, I will drop patch 3. 

> 
> 
> > Baoquan He (3):
> >    kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP
> >    drivers/base/cpu: crash data showing should depends on KEXEC_CORE
> >    s390/Kconfig: drop select of KEXEC
> > 
> >   arch/arm/include/asm/kexec.h | 4 ----
> >   arch/s390/Kconfig            | 1 -
> >   drivers/base/cpu.c           | 6 +++---
> >   kernel/Kconfig.kexec         | 1 -
> >   4 files changed, 3 insertions(+), 9 deletions(-)
> > 
>