[PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo

STALE1882d

5 messages, 3 authors, 2021-06-09 · open the first message on its own page

[PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo

From: Pingfan Liu <hidden>
Date: 2021-06-08 10:34:27

As mentioned in kernel commit 1d50e5d0c505 ("crash_core, vmcoreinfo:
Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the
formula:
    #define SECTIONS_SHIFT    (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate
PAGES_PER_SECTION in makedumpfile just like kernel.

Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g.
recently in kernel commit f0b13ee23241 ("arm64/sparsemem: reduce
SECTION_SIZE_BITS"). But user space wants a stable interface to get this
info. Such info is impossible to be deduced from a crashdump vmcore.
Hence append SECTION_SIZE_BITS to vmcoreinfo.

Signed-off-by: Pingfan Liu <redacted>
Cc: Bhupesh Sharma <redacted>
Cc: Kazuhito Hagio <redacted>
Cc: Dave Young <redacted>
Cc: Baoquan He <redacted>
Cc: Boris Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Anderson <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: kexec@lists.infradead.org
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
---
 kernel/crash_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 825284baaf46..684a6061a13a 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c

@@ -464,6 +464,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
 	VMCOREINFO_STRUCT_SIZE(mem_section);
 	VMCOREINFO_OFFSET(mem_section, section_mem_map);
+	VMCOREINFO_NUMBER(SECTION_SIZE_BITS);
 	VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);
 #endif
 	VMCOREINFO_STRUCT_SIZE(page);

-- 
2.29.2


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Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo

From: Baoquan He <hidden>
Date: 2021-06-08 14:24:57

On 06/08/21 at 06:33am, Pingfan Liu wrote:

As mentioned in kernel commit 1d50e5d0c505 ("crash_core, vmcoreinfo:
Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the
formula:
    #define SECTIONS_SHIFT    (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate
PAGES_PER_SECTION in makedumpfile just like kernel.

Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g.
recently in kernel commit f0b13ee23241 ("arm64/sparsemem: reduce
SECTION_SIZE_BITS"). But user space wants a stable interface to get this
info. Such info is impossible to be deduced from a crashdump vmcore.
Hence append SECTION_SIZE_BITS to vmcoreinfo.

Signed-off-by: Pingfan Liu <redacted>
Cc: Bhupesh Sharma <redacted>
Cc: Kazuhito Hagio <redacted>
Cc: Dave Young <redacted>
Cc: Baoquan He <redacted>
Cc: Boris Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Anderson <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: kexec@lists.infradead.org
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org


Add the discussion of the original thread in kexec ML for reference:
http://lists.infradead.org/pipermail/kexec/2021-June/022676.html

This looks good to me.

Acked-by: Baoquan He <redacted>

quoted hunk

---
 kernel/crash_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 825284baaf46..684a6061a13a 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c

@@ -464,6 +464,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
 	VMCOREINFO_STRUCT_SIZE(mem_section);
 	VMCOREINFO_OFFSET(mem_section, section_mem_map);
+	VMCOREINFO_NUMBER(SECTION_SIZE_BITS);
 	VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);
 #endif
 	VMCOREINFO_STRUCT_SIZE(page);

-- 
2.29.2


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Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo

From: Andrew Morton <akpm@linux-foundation.org>
Date: 2021-06-08 21:14:14

On Tue, 8 Jun 2021 22:24:32 +0800 Baoquan He [off-list ref] wrote:

On 06/08/21 at 06:33am, Pingfan Liu wrote:

quoted

As mentioned in kernel commit 1d50e5d0c505 ("crash_core, vmcoreinfo:
Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the
formula:
    #define SECTIONS_SHIFT    (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate
PAGES_PER_SECTION in makedumpfile just like kernel.

Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g.
recently in kernel commit f0b13ee23241 ("arm64/sparsemem: reduce
SECTION_SIZE_BITS"). But user space wants a stable interface to get this
info. Such info is impossible to be deduced from a crashdump vmcore.
Hence append SECTION_SIZE_BITS to vmcoreinfo.

...

Add the discussion of the original thread in kexec ML for reference:
http://lists.infradead.org/pipermail/kexec/2021-June/022676.html

I added a Link: for this.

This looks good to me.

Acked-by: Baoquan He <redacted>

I'm thinking we should backport this at least to Fixes:f0b13ee23241. 
But perhaps it's simpler to just backport it as far as possible, so I
added a bare cc:stable with no Fixes:.  Thoughts?

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linux-arm-kernel@lists.infradead.org
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Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo

From: Pingfan Liu <hidden>
Date: 2021-06-09 00:17:00

Correct mail address of Kazuhito

On Tue, Jun 8, 2021 at 6:34 PM Pingfan Liu [off-list ref] wrote:

quoted hunk

As mentioned in kernel commit 1d50e5d0c505 ("crash_core, vmcoreinfo:
Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the
formula:
    #define SECTIONS_SHIFT    (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate
PAGES_PER_SECTION in makedumpfile just like kernel.

Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g.
recently in kernel commit f0b13ee23241 ("arm64/sparsemem: reduce
SECTION_SIZE_BITS"). But user space wants a stable interface to get this
info. Such info is impossible to be deduced from a crashdump vmcore.
Hence append SECTION_SIZE_BITS to vmcoreinfo.

Signed-off-by: Pingfan Liu <redacted>
Cc: Bhupesh Sharma <redacted>
Cc: Kazuhito Hagio <redacted>
Cc: Dave Young <redacted>
Cc: Baoquan He <redacted>
Cc: Boris Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Anderson <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: kexec@lists.infradead.org
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
---
 kernel/crash_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 825284baaf46..684a6061a13a 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c

@@ -464,6 +464,7 @@ static int __init crash_save_vmcoreinfo_init(void)
        VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
        VMCOREINFO_STRUCT_SIZE(mem_section);
        VMCOREINFO_OFFSET(mem_section, section_mem_map);
+       VMCOREINFO_NUMBER(SECTION_SIZE_BITS);
        VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);
 #endif
        VMCOREINFO_STRUCT_SIZE(page);
--

2.29.2

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Re: [PATCH] crash_core, vmcoreinfo: Append 'SECTION_SIZE_BITS' to vmcoreinfo

From: Baoquan He <hidden>
Date: 2021-06-09 02:47:29

On 06/08/21 at 02:14pm, Andrew Morton wrote:

On Tue, 8 Jun 2021 22:24:32 +0800 Baoquan He [off-list ref] wrote:

quoted

On 06/08/21 at 06:33am, Pingfan Liu wrote:

quoted

As mentioned in kernel commit 1d50e5d0c505 ("crash_core, vmcoreinfo:
Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the
formula:
    #define SECTIONS_SHIFT    (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate
PAGES_PER_SECTION in makedumpfile just like kernel.

Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g.
recently in kernel commit f0b13ee23241 ("arm64/sparsemem: reduce
SECTION_SIZE_BITS"). But user space wants a stable interface to get this
info. Such info is impossible to be deduced from a crashdump vmcore.
Hence append SECTION_SIZE_BITS to vmcoreinfo.

...

Add the discussion of the original thread in kexec ML for reference:
http://lists.infradead.org/pipermail/kexec/2021-June/022676.html

I added a Link: for this.

Thanks, Andrew.

quoted

This looks good to me.

Acked-by: Baoquan He <redacted>

I'm thinking we should backport this at least to Fixes:f0b13ee23241. 
But perhaps it's simpler to just backport it as far as possible, so I
added a bare cc:stable with no Fixes:.  Thoughts?

Yeah, it should add cc:stable, thanks. Otherwise it will break
vmcore dumping on 5.12 stable kernel even though with the updated
makedumpfile utility. Fixes:f0b13ee23241 will help stable kernel
maintainer easier to identify which kernel this patch need be applied
on? If only having cc:stable with no Fixes is allowed, it's also OK. 


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