crash_core: export vmemmap when CONFIG_SPARSEMEM_VMEMMAP is enabled

In memory_model.h, if CONFIG_SPARSEMEM_VMEMMAP is configed, kernel will
use vmemmap to do the __pfn_to_page/page_to_pfn, and kernel will not use
the "classic sparse" to do the __pfn_to_page/page_to_pfn.

So export the vmemmap when CONFIG_SPARSEMEM_VMEMMAP is configed.  This
makes the user applications (crash, etc) get faster
pfn_to_page/page_to_pfn operations too.

Link: https://lkml.kernel.org/r/20240227014952.3184-1-shijie@os.amperecomputing.com
Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Kazuhito Hagio <k-hagio-ab@nec.com>
Cc: Lianbo Jiang <lijiang@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c
index 8f77e238a54f54aa1dc944c8ee69fcb64a24ea8e..f95516cd45bbe29661adc4da4c530c813ad209fe 100644 (file)
--- a/kernel/vmcore_info.c
+++ b/kernel/vmcore_info.c
@@ -152,6 +152,9 @@ static int __init crash_save_vmcoreinfo_init(void)
        VMCOREINFO_SYMBOL(mem_map);
        VMCOREINFO_SYMBOL(contig_page_data);
 #endif
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+       VMCOREINFO_SYMBOL_ARRAY(vmemmap);
+#endif
 #ifdef CONFIG_SPARSEMEM
        VMCOREINFO_SYMBOL_ARRAY(mem_section);
        VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);