Re: [RESEND PATCH v5 06/11] ppc64/kexec_file: restrict memory usage of kdump kernel

From: Hari Bathini
Date: Tue Jul 28 2020 - 15:34:43 EST

On 28/07/20 7:14 pm, Michael Ellerman wrote:
Hari Bathini <hbathini@xxxxxxxxxxxxx> writes:
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 2df6f4273ddd..8df085a22fd7 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -17,9 +17,21 @@
#include <linux/kexec.h>
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
+#include <linux/of_device.h>
#include <linux/memblock.h>
+#include <linux/slab.h>
+#include <asm/drmem.h>
#include <asm/kexec_ranges.h>
+struct umem_info {
+ uint64_t *buf; /* data buffer for usable-memory property */
+ uint32_t idx; /* current index */
+ uint32_t size; /* size allocated for the data buffer */

Use kernel types please, u64, u32.

+ /* usable memory ranges to look up */
+ const struct crash_mem *umrngs;


Given it's part of the umem_info struct could it just be "ranges"?

True. Actually, having crash_mem_range *ranges + u32 nr_ranges and populating them seems better. Will do that..

+ return NULL;
+ }

um_info->size = new_size;

+ memset(tbuf + um_info->idx, 0, MEM_RANGE_CHUNK_SZ);

Just pass __GFP_ZERO to krealloc?

There are patches submitted to stable fixing a few modules that use krealloc with __GFP_ZERO. Also, this zeroing is not really needed.
I will drop the memset instead..