On 19/01/2023 19:29:52, Laurent Dufour wrote:

On 15/01/2023 16:02:02, Sourabh Jain wrote:

quoted

On architectures like PowerPC the crash notes are available for all
possible CPUs. So let's populate the elfcorehdr for all possible
CPUs having crash notes to avoid updating elfcorehdr during in-kernel
crash update on CPU hotplug events.

The similar technique is used in kexec-tool for kexec_load case.

Signed-off-by: Sourabh Jain <redacted>
---
 kernel/crash_core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

This patch is not applying on ppc/next (53ab112a9508).

As far as I could see, crash_prepare_elf64_headers() is defined in the file
kernel/kexec_file.c and that's not recent, see babac4a84a88 (kexec_file,
x86: move re-factored code to generic side, 2018-04-13)

Am I missing something?

My mistake, sounds that your series is based on top of the Eric's one (not yet upstream):

https://lore.kernel.org/lkml/20230118213544.2128-1-eric.devolder@oracle.com/ (local)

quoted

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 910d377ea317e..19f987b3851e8 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c

@@ -364,8 +364,8 @@ int crash_prepare_elf64_headers(struct kimage *image, struct crash_mem *mem,
 	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
 	ehdr->e_phentsize = sizeof(Elf64_Phdr);
 
-	/* Prepare one phdr of type PT_NOTE for each present CPU */
-	for_each_present_cpu(cpu) {
+	/* Prepare one phdr of type PT_NOTE for possible CPU with crash note. */
+	for_each_possible_cpu(cpu) {
 #ifdef CONFIG_CRASH_HOTPLUG
 		if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {
 			/* Skip the soon-to-be offlined cpu */

@@ -373,8 +373,11 @@ int crash_prepare_elf64_headers(struct kimage *image, struct crash_mem *mem,
 				continue;
 		}
 #endif
-		phdr->p_type = PT_NOTE;
 		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
+		if (!notes_addr)
+			continue;
+
+		phdr->p_type = PT_NOTE;
 		phdr->p_offset = phdr->p_paddr = notes_addr;
 		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
 		(ehdr->e_phnum)++;