Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Hari Bathini]

On Friday 18 August 2017 05:27 PM, Michal Suchánek wrote:

On Fri, 18 Aug 2017 16:20:53 +0530
Hari Bathini  wrote:


Hi Michal,


Thanks for the patches. I tried testing with the patches:

[0.00] fadump: Firmware-assisted dump is active.
[0.00] fadump: Modifying command line to enforce the
additional parameters passed through 'fadump_extra_args='
[0.00] fadump: Original command line:
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M
"fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2"
rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
[0.00] fadump: Modified command line:
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M
"fadump_extra_args nr_cpus=1 numa=off udev.childern-max=2"
rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap

Looks like the quotes are retained not enforcing the parameters...

Hello,

You are passing an argument >>"fadump_extra_args<<  - that is an
argument containing a quote in the name. I did not test this scenario


Actually, this was not intentional..
I passed fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2" 
through grub loader
but chosen/bootargs ended up having "fadump_extra_args=nr_cpus=1 
numa=off udev.childern-max=2".

Need to check why that is..

Thanks
Hari


assuming the argument name would not match in this case. It would
probably not match if the quote was in the middle of the argument
name but at the start it is skipped. Note that due to the requirement
to remove quotes symmetrically which is added in the third patch this
case does not break the commandline - it merely makes the arguments
ineffective.

The format suggested in the documentation is

fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2"<< - that

is quotes around the value. This format worked in my testing.

Unfortunately, the format with quote before argument name would
probably require another extra parameter to the callback to detect
properly.

Thanks

Michal


I am yet to test the patches in other scenarios though..


Thanks

Hari


On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote:

From: Hari Bathini 

With fadump (dump capture) kernel booting like a regular kernel, it
needs almost the same amount of memory to boot as the production
kernel, which is unwarranted for a dump capture kernel. But with no
option to disable some of the unnecessary subsystems in fadump
kernel, that much memory is wasted on fadump, depriving the
production kernel of that memory.

Introduce kernel parameter 'fadump_extra_args=' that would take
regular parameters as a space separated quoted string, to be
enforced when fadump is active. This 'fadump_extra_args=' parameter
can be leveraged to pass parameters like nr_cpus=1,
cgroup_disable=memory and numa=off, to disable unwarranted
resources/subsystems.

Also, ensure the log "Firmware-assisted dump is active" is printed
early in the boot process to put the subsequent fadump messages in
context.

Suggested-by: Michael Ellerman 
Signed-off-by: Hari Bathini 
Signed-off-by: Michal Suchanek 
---
Changes from v6:
Correct and simplify quote handling. Ideally I would like to extend
parse_args to give the length of the original quoted value to
callback. However, parse_args removes at most one doubel-quote from
the start and one from the end so that is easy to detect. Otherwise
all other users will have to be updated to trash the new argument.
---
   arch/powerpc/include/asm/fadump.h |   2 +
   arch/powerpc/kernel/fadump.c  | 109
--
arch/powerpc/kernel/prom.c|   7 +++ 3 files changed, 115
insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h
b/arch/powerpc/include/asm/fadump.h index
ce88bbe1d809..98ae00943fb3 100644 ---
a/arch/powerpc/include/asm/fadump.h +++
b/arch/powerpc/include/asm/fadump.h @@ -208,11 +208,13 @@ extern
int early_init_dt_scan_fw_dump(unsigned long node, const char
*uname, int depth, void *data); extern int fadump_reserve_mem(void);
   extern int setup_fadump(void);
+extern void enforce_fadump_extra_args(char *cmdline);
   extern int is_fadump_active(void);
   extern void crash_fadump(struct pt_regs *, const char *);
   extern void fadump_cleanup(void);

   #else/* CONFIG_FA_DUMP */
+static inline void enforce_fadump_extra_args(char *cmdline) { }
   static inline int is_fadump_active(void) { return 0; }
   static inline void crash_fadump(struct pt_regs *regs, const char
*str) { } #endif
diff --git a/arch/powerpc/kernel/fadump.c
b/arch/powerpc/kernel/fadump.c index dc0c49cfd90a..a1614d9b8a21
100644 --- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned
long node,
 * dump data waiting for us.
 

Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Hari Bathini]

On Friday 18 August 2017 05:27 PM, Michal Suchánek wrote:

On Fri, 18 Aug 2017 16:20:53 +0530
Hari Bathini  wrote:


Hi Michal,


Thanks for the patches. I tried testing with the patches:

[0.00] fadump: Firmware-assisted dump is active.
[0.00] fadump: Modifying command line to enforce the
additional parameters passed through 'fadump_extra_args='
[0.00] fadump: Original command line:
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M
"fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2"
rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
[0.00] fadump: Modified command line:
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M
"fadump_extra_args nr_cpus=1 numa=off udev.childern-max=2"
rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap

Looks like the quotes are retained not enforcing the parameters...

Hello,

You are passing an argument >>"fadump_extra_args<<  - that is an
argument containing a quote in the name. I did not test this scenario


Actually, this was not intentional..
I passed fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2" 
through grub loader
but chosen/bootargs ended up having "fadump_extra_args=nr_cpus=1 
numa=off udev.childern-max=2".

Need to check why that is..

Thanks
Hari


assuming the argument name would not match in this case. It would
probably not match if the quote was in the middle of the argument
name but at the start it is skipped. Note that due to the requirement
to remove quotes symmetrically which is added in the third patch this
case does not break the commandline - it merely makes the arguments
ineffective.

The format suggested in the documentation is

fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2"<< - that

is quotes around the value. This format worked in my testing.

Unfortunately, the format with quote before argument name would
probably require another extra parameter to the callback to detect
properly.

Thanks

Michal


I am yet to test the patches in other scenarios though..


Thanks

Hari


On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote:

From: Hari Bathini 

With fadump (dump capture) kernel booting like a regular kernel, it
needs almost the same amount of memory to boot as the production
kernel, which is unwarranted for a dump capture kernel. But with no
option to disable some of the unnecessary subsystems in fadump
kernel, that much memory is wasted on fadump, depriving the
production kernel of that memory.

Introduce kernel parameter 'fadump_extra_args=' that would take
regular parameters as a space separated quoted string, to be
enforced when fadump is active. This 'fadump_extra_args=' parameter
can be leveraged to pass parameters like nr_cpus=1,
cgroup_disable=memory and numa=off, to disable unwarranted
resources/subsystems.

Also, ensure the log "Firmware-assisted dump is active" is printed
early in the boot process to put the subsequent fadump messages in
context.

Suggested-by: Michael Ellerman 
Signed-off-by: Hari Bathini 
Signed-off-by: Michal Suchanek 
---
Changes from v6:
Correct and simplify quote handling. Ideally I would like to extend
parse_args to give the length of the original quoted value to
callback. However, parse_args removes at most one doubel-quote from
the start and one from the end so that is easy to detect. Otherwise
all other users will have to be updated to trash the new argument.
---
   arch/powerpc/include/asm/fadump.h |   2 +
   arch/powerpc/kernel/fadump.c  | 109
--
arch/powerpc/kernel/prom.c|   7 +++ 3 files changed, 115
insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h
b/arch/powerpc/include/asm/fadump.h index
ce88bbe1d809..98ae00943fb3 100644 ---
a/arch/powerpc/include/asm/fadump.h +++
b/arch/powerpc/include/asm/fadump.h @@ -208,11 +208,13 @@ extern
int early_init_dt_scan_fw_dump(unsigned long node, const char
*uname, int depth, void *data); extern int fadump_reserve_mem(void);
   extern int setup_fadump(void);
+extern void enforce_fadump_extra_args(char *cmdline);
   extern int is_fadump_active(void);
   extern void crash_fadump(struct pt_regs *, const char *);
   extern void fadump_cleanup(void);

   #else/* CONFIG_FA_DUMP */
+static inline void enforce_fadump_extra_args(char *cmdline) { }
   static inline int is_fadump_active(void) { return 0; }
   static inline void crash_fadump(struct pt_regs *regs, const char
*str) { } #endif
diff --git a/arch/powerpc/kernel/fadump.c
b/arch/powerpc/kernel/fadump.c index dc0c49cfd90a..a1614d9b8a21
100644 --- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned
long node,
 * dump data waiting for us.
 */
fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump",
NULL);
-   if (fdm_active)
+   if 

Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Michal Suchánek]

On Fri, 18 Aug 2017 16:20:53 +0530
Hari Bathini  wrote:

> Hi Michal,
> 
> 
> Thanks for the patches. I tried testing with the patches:
> 
> [0.00] fadump: Firmware-assisted dump is active.
> [0.00] fadump: Modifying command line to enforce the
> additional parameters passed through 'fadump_extra_args='
> [0.00] fadump: Original command line: 
> BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
> ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M 
> "fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2" 
> rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
> [0.00] fadump: Modified command line: 
> BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
> ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M
> "fadump_extra_args nr_cpus=1 numa=off udev.childern-max=2"
> rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
> 
> Looks like the quotes are retained not enforcing the parameters...

Hello,

You are passing an argument >>"fadump_extra_args<<  - that is an
argument containing a quote in the name. I did not test this scenario
assuming the argument name would not match in this case. It would
probably not match if the quote was in the middle of the argument
name but at the start it is skipped. Note that due to the requirement
to remove quotes symmetrically which is added in the third patch this
case does not break the commandline - it merely makes the arguments
ineffective.

The format suggested in the documentation is
>>fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2"<< - that
is quotes around the value. This format worked in my testing.

Unfortunately, the format with quote before argument name would
probably require another extra parameter to the callback to detect
properly.

Thanks

Michal

> 
> I am yet to test the patches in other scenarios though..
> 
> 
> Thanks
> 
> Hari
> 
> 
> On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote:
> > From: Hari Bathini 
> >
> > With fadump (dump capture) kernel booting like a regular kernel, it
> > needs almost the same amount of memory to boot as the production
> > kernel, which is unwarranted for a dump capture kernel. But with no
> > option to disable some of the unnecessary subsystems in fadump
> > kernel, that much memory is wasted on fadump, depriving the
> > production kernel of that memory.
> >
> > Introduce kernel parameter 'fadump_extra_args=' that would take
> > regular parameters as a space separated quoted string, to be
> > enforced when fadump is active. This 'fadump_extra_args=' parameter
> > can be leveraged to pass parameters like nr_cpus=1,
> > cgroup_disable=memory and numa=off, to disable unwarranted
> > resources/subsystems.
> >
> > Also, ensure the log "Firmware-assisted dump is active" is printed
> > early in the boot process to put the subsequent fadump messages in
> > context.
> >
> > Suggested-by: Michael Ellerman 
> > Signed-off-by: Hari Bathini 
> > Signed-off-by: Michal Suchanek 
> > ---
> > Changes from v6:
> > Correct and simplify quote handling. Ideally I would like to extend
> > parse_args to give the length of the original quoted value to
> > callback. However, parse_args removes at most one doubel-quote from
> > the start and one from the end so that is easy to detect. Otherwise
> > all other users will have to be updated to trash the new argument.
> > ---
> >   arch/powerpc/include/asm/fadump.h |   2 +
> >   arch/powerpc/kernel/fadump.c  | 109
> > --
> > arch/powerpc/kernel/prom.c|   7 +++ 3 files changed, 115
> > insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/fadump.h
> > b/arch/powerpc/include/asm/fadump.h index
> > ce88bbe1d809..98ae00943fb3 100644 ---
> > a/arch/powerpc/include/asm/fadump.h +++
> > b/arch/powerpc/include/asm/fadump.h @@ -208,11 +208,13 @@ extern
> > int early_init_dt_scan_fw_dump(unsigned long node, const char
> > *uname, int depth, void *data); extern int fadump_reserve_mem(void);
> >   extern int setup_fadump(void);
> > +extern void enforce_fadump_extra_args(char *cmdline);
> >   extern int is_fadump_active(void);
> >   extern void crash_fadump(struct pt_regs *, const char *);
> >   extern void fadump_cleanup(void);
> >
> >   #else /* CONFIG_FA_DUMP */
> > +static inline void enforce_fadump_extra_args(char *cmdline) { }
> >   static inline int is_fadump_active(void) { return 0; }
> >   static inline void crash_fadump(struct pt_regs *regs, const char
> > *str) { } #endif
> > diff --git a/arch/powerpc/kernel/fadump.c
> > b/arch/powerpc/kernel/fadump.c index dc0c49cfd90a..a1614d9b8a21
> > 100644 --- a/arch/powerpc/kernel/fadump.c
> > +++ b/arch/powerpc/kernel/fadump.c
> > @@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned
> > long node,
> >  * dump data waiting for us.
> >  */
> > fdm_active = 

Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Michal Suchánek]

On Fri, 18 Aug 2017 16:20:53 +0530
Hari Bathini  wrote:

> Hi Michal,
> 
> 
> Thanks for the patches. I tried testing with the patches:
> 
> [0.00] fadump: Firmware-assisted dump is active.
> [0.00] fadump: Modifying command line to enforce the
> additional parameters passed through 'fadump_extra_args='
> [0.00] fadump: Original command line: 
> BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
> ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M 
> "fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2" 
> rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
> [0.00] fadump: Modified command line: 
> BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root
> ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M
> "fadump_extra_args nr_cpus=1 numa=off udev.childern-max=2"
> rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
> 
> Looks like the quotes are retained not enforcing the parameters...

Hello,

You are passing an argument >>"fadump_extra_args<<  - that is an
argument containing a quote in the name. I did not test this scenario
assuming the argument name would not match in this case. It would
probably not match if the quote was in the middle of the argument
name but at the start it is skipped. Note that due to the requirement
to remove quotes symmetrically which is added in the third patch this
case does not break the commandline - it merely makes the arguments
ineffective.

The format suggested in the documentation is
>>fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2"<< - that
is quotes around the value. This format worked in my testing.

Unfortunately, the format with quote before argument name would
probably require another extra parameter to the callback to detect
properly.

Thanks

Michal

> 
> I am yet to test the patches in other scenarios though..
> 
> 
> Thanks
> 
> Hari
> 
> 
> On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote:
> > From: Hari Bathini 
> >
> > With fadump (dump capture) kernel booting like a regular kernel, it
> > needs almost the same amount of memory to boot as the production
> > kernel, which is unwarranted for a dump capture kernel. But with no
> > option to disable some of the unnecessary subsystems in fadump
> > kernel, that much memory is wasted on fadump, depriving the
> > production kernel of that memory.
> >
> > Introduce kernel parameter 'fadump_extra_args=' that would take
> > regular parameters as a space separated quoted string, to be
> > enforced when fadump is active. This 'fadump_extra_args=' parameter
> > can be leveraged to pass parameters like nr_cpus=1,
> > cgroup_disable=memory and numa=off, to disable unwarranted
> > resources/subsystems.
> >
> > Also, ensure the log "Firmware-assisted dump is active" is printed
> > early in the boot process to put the subsequent fadump messages in
> > context.
> >
> > Suggested-by: Michael Ellerman 
> > Signed-off-by: Hari Bathini 
> > Signed-off-by: Michal Suchanek 
> > ---
> > Changes from v6:
> > Correct and simplify quote handling. Ideally I would like to extend
> > parse_args to give the length of the original quoted value to
> > callback. However, parse_args removes at most one doubel-quote from
> > the start and one from the end so that is easy to detect. Otherwise
> > all other users will have to be updated to trash the new argument.
> > ---
> >   arch/powerpc/include/asm/fadump.h |   2 +
> >   arch/powerpc/kernel/fadump.c  | 109
> > --
> > arch/powerpc/kernel/prom.c|   7 +++ 3 files changed, 115
> > insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/fadump.h
> > b/arch/powerpc/include/asm/fadump.h index
> > ce88bbe1d809..98ae00943fb3 100644 ---
> > a/arch/powerpc/include/asm/fadump.h +++
> > b/arch/powerpc/include/asm/fadump.h @@ -208,11 +208,13 @@ extern
> > int early_init_dt_scan_fw_dump(unsigned long node, const char
> > *uname, int depth, void *data); extern int fadump_reserve_mem(void);
> >   extern int setup_fadump(void);
> > +extern void enforce_fadump_extra_args(char *cmdline);
> >   extern int is_fadump_active(void);
> >   extern void crash_fadump(struct pt_regs *, const char *);
> >   extern void fadump_cleanup(void);
> >
> >   #else /* CONFIG_FA_DUMP */
> > +static inline void enforce_fadump_extra_args(char *cmdline) { }
> >   static inline int is_fadump_active(void) { return 0; }
> >   static inline void crash_fadump(struct pt_regs *regs, const char
> > *str) { } #endif
> > diff --git a/arch/powerpc/kernel/fadump.c
> > b/arch/powerpc/kernel/fadump.c index dc0c49cfd90a..a1614d9b8a21
> > 100644 --- a/arch/powerpc/kernel/fadump.c
> > +++ b/arch/powerpc/kernel/fadump.c
> > @@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned
> > long node,
> >  * dump data waiting for us.
> >  */
> > fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump",
> > NULL);
> > -   if (fdm_active)
> > +   if (fdm_active) {
> > +   

Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Hari Bathini]

Hi Michal,


Thanks for the patches. I tried testing with the patches:

[0.00] fadump: Firmware-assisted dump is active.
[0.00] fadump: Modifying command line to enforce the additional 
parameters passed through 'fadump_extra_args='
[0.00] fadump: Original command line: 
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root ro 
crashkernel=2048M fadump=on fadump_reserve_mem=1024M 
"fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2" 
rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
[0.00] fadump: Modified command line: 
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root ro 
crashkernel=2048M fadump=on fadump_reserve_mem=1024M "fadump_extra_args 
nr_cpus=1 numa=off udev.childern-max=2" rd.lvm.lv=rhel/root 
rd.lvm.lv=rhel/swap


Looks like the quotes are retained not enforcing the parameters...

I am yet to test the patches in other scenarios though..


Thanks

Hari


On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote:

From: Hari Bathini 

With fadump (dump capture) kernel booting like a regular kernel, it needs
almost the same amount of memory to boot as the production kernel, which is
unwarranted for a dump capture kernel. But with no option to disable some
of the unnecessary subsystems in fadump kernel, that much memory is wasted
on fadump, depriving the production kernel of that memory.

Introduce kernel parameter 'fadump_extra_args=' that would take regular
parameters as a space separated quoted string, to be enforced when fadump
is active. This 'fadump_extra_args=' parameter can be leveraged to pass
parameters like nr_cpus=1, cgroup_disable=memory and numa=off, to disable
unwarranted resources/subsystems.

Also, ensure the log "Firmware-assisted dump is active" is printed early
in the boot process to put the subsequent fadump messages in context.

Suggested-by: Michael Ellerman 
Signed-off-by: Hari Bathini 
Signed-off-by: Michal Suchanek 
---
Changes from v6:
Correct and simplify quote handling. Ideally I would like to extend
parse_args to give the length of the original quoted value to callback.
However, parse_args removes at most one doubel-quote from the start and
one from the end so that is easy to detect. Otherwise all other users
will have to be updated to trash the new argument.
---
  arch/powerpc/include/asm/fadump.h |   2 +
  arch/powerpc/kernel/fadump.c  | 109 --
  arch/powerpc/kernel/prom.c|   7 +++
  3 files changed, 115 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h 
b/arch/powerpc/include/asm/fadump.h
index ce88bbe1d809..98ae00943fb3 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned long node,
const char *uname, int depth, void *data);
  extern int fadump_reserve_mem(void);
  extern int setup_fadump(void);
+extern void enforce_fadump_extra_args(char *cmdline);
  extern int is_fadump_active(void);
  extern void crash_fadump(struct pt_regs *, const char *);
  extern void fadump_cleanup(void);

  #else /* CONFIG_FA_DUMP */
+static inline void enforce_fadump_extra_args(char *cmdline) { }
  static inline int is_fadump_active(void) { return 0; }
  static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
  #endif
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index dc0c49cfd90a..a1614d9b8a21 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned long node,
 * dump data waiting for us.
 */
fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL);
-   if (fdm_active)
+   if (fdm_active) {
+   pr_info("Firmware-assisted dump is active.\n");
fw_dump.dump_active = 1;
+   }

/* Get the sizes required to store dump data for the firmware provided
 * dump sections.
@@ -332,8 +334,11 @@ int __init fadump_reserve_mem(void)
  {
unsigned long base, size, memory_boundary;

-   if (!fw_dump.fadump_enabled)
+   if (!fw_dump.fadump_enabled) {
+   if (fw_dump.dump_active)
+   pr_warn("Firmware-assisted dump was active but kernel booted 
with fadump disabled!\n");
return 0;
+   }

if (!fw_dump.fadump_supported) {
printk(KERN_INFO "Firmware-assisted dump is not supported on"
@@ -373,7 +378,6 @@ int __init fadump_reserve_mem(void)
memory_boundary = memblock_end_of_DRAM();

if (fw_dump.dump_active) {
-   printk(KERN_INFO "Firmware-assisted dump is active.\n");
/*
 * If last boot has crashed then reserve all the memory
 * above boot_memory_size so that we don't touch it 

Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Hari Bathini]

Hi Michal,


Thanks for the patches. I tried testing with the patches:

[0.00] fadump: Firmware-assisted dump is active.
[0.00] fadump: Modifying command line to enforce the additional 
parameters passed through 'fadump_extra_args='
[0.00] fadump: Original command line: 
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root ro 
crashkernel=2048M fadump=on fadump_reserve_mem=1024M 
"fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2" 
rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap
[0.00] fadump: Modified command line: 
BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root ro 
crashkernel=2048M fadump=on fadump_reserve_mem=1024M "fadump_extra_args 
nr_cpus=1 numa=off udev.childern-max=2" rd.lvm.lv=rhel/root 
rd.lvm.lv=rhel/swap


Looks like the quotes are retained not enforcing the parameters...

I am yet to test the patches in other scenarios though..


Thanks

Hari


On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote:

From: Hari Bathini 

With fadump (dump capture) kernel booting like a regular kernel, it needs
almost the same amount of memory to boot as the production kernel, which is
unwarranted for a dump capture kernel. But with no option to disable some
of the unnecessary subsystems in fadump kernel, that much memory is wasted
on fadump, depriving the production kernel of that memory.

Introduce kernel parameter 'fadump_extra_args=' that would take regular
parameters as a space separated quoted string, to be enforced when fadump
is active. This 'fadump_extra_args=' parameter can be leveraged to pass
parameters like nr_cpus=1, cgroup_disable=memory and numa=off, to disable
unwarranted resources/subsystems.

Also, ensure the log "Firmware-assisted dump is active" is printed early
in the boot process to put the subsequent fadump messages in context.

Suggested-by: Michael Ellerman 
Signed-off-by: Hari Bathini 
Signed-off-by: Michal Suchanek 
---
Changes from v6:
Correct and simplify quote handling. Ideally I would like to extend
parse_args to give the length of the original quoted value to callback.
However, parse_args removes at most one doubel-quote from the start and
one from the end so that is easy to detect. Otherwise all other users
will have to be updated to trash the new argument.
---
  arch/powerpc/include/asm/fadump.h |   2 +
  arch/powerpc/kernel/fadump.c  | 109 --
  arch/powerpc/kernel/prom.c|   7 +++
  3 files changed, 115 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h 
b/arch/powerpc/include/asm/fadump.h
index ce88bbe1d809..98ae00943fb3 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned long node,
const char *uname, int depth, void *data);
  extern int fadump_reserve_mem(void);
  extern int setup_fadump(void);
+extern void enforce_fadump_extra_args(char *cmdline);
  extern int is_fadump_active(void);
  extern void crash_fadump(struct pt_regs *, const char *);
  extern void fadump_cleanup(void);

  #else /* CONFIG_FA_DUMP */
+static inline void enforce_fadump_extra_args(char *cmdline) { }
  static inline int is_fadump_active(void) { return 0; }
  static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
  #endif
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index dc0c49cfd90a..a1614d9b8a21 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned long node,
 * dump data waiting for us.
 */
fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL);
-   if (fdm_active)
+   if (fdm_active) {
+   pr_info("Firmware-assisted dump is active.\n");
fw_dump.dump_active = 1;
+   }

/* Get the sizes required to store dump data for the firmware provided
 * dump sections.
@@ -332,8 +334,11 @@ int __init fadump_reserve_mem(void)
  {
unsigned long base, size, memory_boundary;

-   if (!fw_dump.fadump_enabled)
+   if (!fw_dump.fadump_enabled) {
+   if (fw_dump.dump_active)
+   pr_warn("Firmware-assisted dump was active but kernel booted 
with fadump disabled!\n");
return 0;
+   }

if (!fw_dump.fadump_supported) {
printk(KERN_INFO "Firmware-assisted dump is not supported on"
@@ -373,7 +378,6 @@ int __init fadump_reserve_mem(void)
memory_boundary = memblock_end_of_DRAM();

if (fw_dump.dump_active) {
-   printk(KERN_INFO "Firmware-assisted dump is active.\n");
/*
 * If last boot has crashed then reserve all the memory
 * above boot_memory_size so that we don't touch it until
@@ -460,6 +464,105 @@ static int __init early_fadump_reserve_mem(char *p)
  }
  

[PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Michal Suchanek]

From: Hari Bathini 

With fadump (dump capture) kernel booting like a regular kernel, it needs
almost the same amount of memory to boot as the production kernel, which is
unwarranted for a dump capture kernel. But with no option to disable some
of the unnecessary subsystems in fadump kernel, that much memory is wasted
on fadump, depriving the production kernel of that memory.

Introduce kernel parameter 'fadump_extra_args=' that would take regular
parameters as a space separated quoted string, to be enforced when fadump
is active. This 'fadump_extra_args=' parameter can be leveraged to pass
parameters like nr_cpus=1, cgroup_disable=memory and numa=off, to disable
unwarranted resources/subsystems.

Also, ensure the log "Firmware-assisted dump is active" is printed early
in the boot process to put the subsequent fadump messages in context.

Suggested-by: Michael Ellerman 
Signed-off-by: Hari Bathini 
Signed-off-by: Michal Suchanek 
---
Changes from v6:
Correct and simplify quote handling. Ideally I would like to extend
parse_args to give the length of the original quoted value to callback.
However, parse_args removes at most one doubel-quote from the start and
one from the end so that is easy to detect. Otherwise all other users
will have to be updated to trash the new argument.
---
 arch/powerpc/include/asm/fadump.h |   2 +
 arch/powerpc/kernel/fadump.c  | 109 --
 arch/powerpc/kernel/prom.c|   7 +++
 3 files changed, 115 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h 
b/arch/powerpc/include/asm/fadump.h
index ce88bbe1d809..98ae00943fb3 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned long node,
const char *uname, int depth, void *data);
 extern int fadump_reserve_mem(void);
 extern int setup_fadump(void);
+extern void enforce_fadump_extra_args(char *cmdline);
 extern int is_fadump_active(void);
 extern void crash_fadump(struct pt_regs *, const char *);
 extern void fadump_cleanup(void);
 
 #else  /* CONFIG_FA_DUMP */
+static inline void enforce_fadump_extra_args(char *cmdline) { }
 static inline int is_fadump_active(void) { return 0; }
 static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
 #endif
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index dc0c49cfd90a..a1614d9b8a21 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned long node,
 * dump data waiting for us.
 */
fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL);
-   if (fdm_active)
+   if (fdm_active) {
+   pr_info("Firmware-assisted dump is active.\n");
fw_dump.dump_active = 1;
+   }
 
/* Get the sizes required to store dump data for the firmware provided
 * dump sections.
@@ -332,8 +334,11 @@ int __init fadump_reserve_mem(void)
 {
unsigned long base, size, memory_boundary;
 
-   if (!fw_dump.fadump_enabled)
+   if (!fw_dump.fadump_enabled) {
+   if (fw_dump.dump_active)
+   pr_warn("Firmware-assisted dump was active but kernel 
booted with fadump disabled!\n");
return 0;
+   }
 
if (!fw_dump.fadump_supported) {
printk(KERN_INFO "Firmware-assisted dump is not supported on"
@@ -373,7 +378,6 @@ int __init fadump_reserve_mem(void)
memory_boundary = memblock_end_of_DRAM();
 
if (fw_dump.dump_active) {
-   printk(KERN_INFO "Firmware-assisted dump is active.\n");
/*
 * If last boot has crashed then reserve all the memory
 * above boot_memory_size so that we don't touch it until
@@ -460,6 +464,105 @@ static int __init early_fadump_reserve_mem(char *p)
 }
 early_param("fadump_reserve_mem", early_fadump_reserve_mem);
 
+#define FADUMP_EXTRA_ARGS_PARAM"fadump_extra_args="
+#define FADUMP_EXTRA_ARGS_LEN  (strlen(FADUMP_EXTRA_ARGS_PARAM) - 1)
+
+struct param_info {
+   char*cmdline;
+   char*tmp_cmdline;
+   int  shortening;
+};
+
+static void __init fadump_update_params(struct param_info *param_info,
+   char *param, char *val)
+{
+   ptrdiff_t param_offset = param - param_info->tmp_cmdline;
+   size_t vallen = val ? strlen(val) : 0;
+   char *tgt = param_info->cmdline + param_offset +
+   FADUMP_EXTRA_ARGS_LEN - param_info->shortening;
+   int shortening = 0;
+
+   if (!val)
+   return;
+
+   /* remove '=' */
+   *tgt++ = ' ';
+
+   /* next_arg removes one leading and one trailing '"' */
+   if 

[PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel

[Michal Suchanek]

From: Hari Bathini 

With fadump (dump capture) kernel booting like a regular kernel, it needs
almost the same amount of memory to boot as the production kernel, which is
unwarranted for a dump capture kernel. But with no option to disable some
of the unnecessary subsystems in fadump kernel, that much memory is wasted
on fadump, depriving the production kernel of that memory.

Introduce kernel parameter 'fadump_extra_args=' that would take regular
parameters as a space separated quoted string, to be enforced when fadump
is active. This 'fadump_extra_args=' parameter can be leveraged to pass
parameters like nr_cpus=1, cgroup_disable=memory and numa=off, to disable
unwarranted resources/subsystems.

Also, ensure the log "Firmware-assisted dump is active" is printed early
in the boot process to put the subsequent fadump messages in context.

Suggested-by: Michael Ellerman 
Signed-off-by: Hari Bathini 
Signed-off-by: Michal Suchanek 
---
Changes from v6:
Correct and simplify quote handling. Ideally I would like to extend
parse_args to give the length of the original quoted value to callback.
However, parse_args removes at most one doubel-quote from the start and
one from the end so that is easy to detect. Otherwise all other users
will have to be updated to trash the new argument.
---
 arch/powerpc/include/asm/fadump.h |   2 +
 arch/powerpc/kernel/fadump.c  | 109 --
 arch/powerpc/kernel/prom.c|   7 +++
 3 files changed, 115 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h 
b/arch/powerpc/include/asm/fadump.h
index ce88bbe1d809..98ae00943fb3 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned long node,
const char *uname, int depth, void *data);
 extern int fadump_reserve_mem(void);
 extern int setup_fadump(void);
+extern void enforce_fadump_extra_args(char *cmdline);
 extern int is_fadump_active(void);
 extern void crash_fadump(struct pt_regs *, const char *);
 extern void fadump_cleanup(void);
 
 #else  /* CONFIG_FA_DUMP */
+static inline void enforce_fadump_extra_args(char *cmdline) { }
 static inline int is_fadump_active(void) { return 0; }
 static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
 #endif
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index dc0c49cfd90a..a1614d9b8a21 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned long node,
 * dump data waiting for us.
 */
fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL);
-   if (fdm_active)
+   if (fdm_active) {
+   pr_info("Firmware-assisted dump is active.\n");
fw_dump.dump_active = 1;
+   }
 
/* Get the sizes required to store dump data for the firmware provided
 * dump sections.
@@ -332,8 +334,11 @@ int __init fadump_reserve_mem(void)
 {
unsigned long base, size, memory_boundary;
 
-   if (!fw_dump.fadump_enabled)
+   if (!fw_dump.fadump_enabled) {
+   if (fw_dump.dump_active)
+   pr_warn("Firmware-assisted dump was active but kernel 
booted with fadump disabled!\n");
return 0;
+   }
 
if (!fw_dump.fadump_supported) {
printk(KERN_INFO "Firmware-assisted dump is not supported on"
@@ -373,7 +378,6 @@ int __init fadump_reserve_mem(void)
memory_boundary = memblock_end_of_DRAM();
 
if (fw_dump.dump_active) {
-   printk(KERN_INFO "Firmware-assisted dump is active.\n");
/*
 * If last boot has crashed then reserve all the memory
 * above boot_memory_size so that we don't touch it until
@@ -460,6 +464,105 @@ static int __init early_fadump_reserve_mem(char *p)
 }
 early_param("fadump_reserve_mem", early_fadump_reserve_mem);
 
+#define FADUMP_EXTRA_ARGS_PARAM"fadump_extra_args="
+#define FADUMP_EXTRA_ARGS_LEN  (strlen(FADUMP_EXTRA_ARGS_PARAM) - 1)
+
+struct param_info {
+   char*cmdline;
+   char*tmp_cmdline;
+   int  shortening;
+};
+
+static void __init fadump_update_params(struct param_info *param_info,
+   char *param, char *val)
+{
+   ptrdiff_t param_offset = param - param_info->tmp_cmdline;
+   size_t vallen = val ? strlen(val) : 0;
+   char *tgt = param_info->cmdline + param_offset +
+   FADUMP_EXTRA_ARGS_LEN - param_info->shortening;
+   int shortening = 0;
+
+   if (!val)
+   return;
+
+   /* remove '=' */
+   *tgt++ = ' ';
+
+   /* next_arg removes one leading and one trailing '"' */
+   if (*tgt == '"')
+   shortening += 1;
+   if (*(tgt + vallen + shortening) == '"')
+