Messages in this thread | | | Date | Tue, 1 Mar 2022 14:08:34 -0600 | Subject | Re: [PATCH v4 08/10] crash hp: exclude hot remove cpu from elfcorehdr notes | From | Eric DeVolder <> |
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On 2/22/22 22:04, Baoquan He wrote: > On 02/09/22 at 02:57pm, Eric DeVolder wrote: >> Due to use of CPUHP_AP_ONLINE_DYN, upon CPU unplug, the CPU is >> still in the for_each_present_cpu() list when within the >> crash_hotplug_handler(). Thus the CPU must be explicitly excluded >> when building the new list of CPUs. >> >> This change identifies in crash_hotplug_handler() the CPU to be >> excluded, and the check for excluding the CPU in >> crash_prepare_elf64_headers(). > > This looks good to me, and the particularity of cpu hotplug can be > understood well by other code reader. Thanks. > > Acked-by: Baoquan He <bhe@redhat.com> Thank you! eric > >> >> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com> >> --- >> kernel/crash_core.c | 10 ++++++++++ >> kernel/kexec_file.c | 5 +++++ >> 2 files changed, 15 insertions(+) >> >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index 524470e18883..b6942e04a188 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -550,6 +550,16 @@ static void crash_hotplug_handler(unsigned int hp_action, >> /* Flag to differentiate between normal load and hotplug */ >> kexec_crash_image->hotplug_event = true; >> >> + /* >> + * Due to use of CPUHP_AP_ONLINE_DYN, upon unplug and during >> + * this callback, the CPU is still in the for_each_present_cpu() >> + * list. Must explicitly look to exclude this CPU when building >> + * new list. >> + */ >> + kexec_crash_image->offlinecpu = >> + (hp_action == KEXEC_CRASH_HP_REMOVE_CPU) ? >> + (unsigned int)a : ~0U; >> + >> /* Now invoke arch-specific update handler */ >> arch_crash_hotplug_handler(kexec_crash_image, hp_action, a, b); >> >> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c >> index 93bb0c0ce66c..339995d42169 100644 >> --- a/kernel/kexec_file.c >> +++ b/kernel/kexec_file.c >> @@ -1314,6 +1314,11 @@ int crash_prepare_elf64_headers(struct kimage *image, struct crash_mem *mem, >> >> /* Prepare one phdr of type PT_NOTE for each present CPU */ >> for_each_present_cpu(cpu) { >> +#ifdef CONFIG_CRASH_HOTPLUG >> + /* Skip the soon-to-be offlined cpu */ >> + if (image->hotplug_event && (cpu == image->offlinecpu)) >> + continue; >> +#endif >> phdr->p_type = PT_NOTE; >> notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); >> phdr->p_offset = phdr->p_paddr = notes_addr; >> -- >> 2.27.0 >> >
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