[PATCH] initramfs: Panic with memory information

[Florian Fainelli]

On systems with large amounts of reserved memory we may fail to
successfully complete unpack_to_rootfs() and be left with:

 Kernel panic - not syncing: write error

this is not too helpful to understand what happened, so let's wrap the
panic() calls with a surrounding show_mem() such that we have a chance
of understanding the memory conditions leading to these allocation
failures.

Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
---
 init/initramfs.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/init/initramfs.c b/init/initramfs.c
index 55b74d7e5260..9dafda6a401b 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -11,6 +11,7 @@
 #include <linux/utime.h>
 #include <linux/file.h>
 #include <linux/memblock.h>
+#include <linux/mm.h>
 #include <linux/namei.h>
 #include <linux/init_syscalls.h>
 
@@ -45,6 +46,11 @@ static void __init error(char *x)
                message = x;
 }
 
+#define panic_show_mem(...) {  \
+       show_mem(0, NULL);      \
+       panic(__VA_ARGS__);     \
+}
+
 /* link hash */
 
 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
@@ -80,7 +86,7 @@ static char __init *find_link(int major, int minor, int ino,
        }
        q = kmalloc(sizeof(struct hash), GFP_KERNEL);
        if (!q)
-               panic("can't allocate link hash entry");
+               panic_show_mem("can't allocate link hash entry");
        q->major = major;
        q->minor = minor;
        q->ino = ino;
@@ -125,7 +131,7 @@ static void __init dir_add(const char *name, time64_t mtime)
 {
        struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
        if (!de)
-               panic("can't allocate dir_entry buffer");
+               panic_show_mem("can't allocate dir_entry buffer");
        INIT_LIST_HEAD(&de->list);
        de->name = kstrdup(name, GFP_KERNEL);
        de->mtime = mtime;
@@ -460,7 +466,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned 
long len)
        name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
 
        if (!header_buf || !symlink_buf || !name_buf)
-               panic("can't allocate buffers");
+               panic_show_mem("can't allocate buffers");
 
        state = Start;
        this_header = 0;
@@ -607,7 +613,7 @@ static int __init populate_rootfs(void)
        /* Load the built in initramfs */
        char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
        if (err)
-               panic("%s", err); /* Failed to decompress INTERNAL initramfs */
+               panic_show_mem("%s", err); /* Failed to decompress INTERNAL 
initramfs */
 
        if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
                goto done;
-- 
2.25.1