[117/118] initramfs: panic with memory information

Commit Message

Andrew Morton Feb. 26, 2021, 1:22 a.m. UTC

From: Florian Fainelli <[e-mail]>
Subject: initramfs: panic with memory information

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.

[[e-mail]: replace macro with C function]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Florian Fainelli <[e-mail]>
Cc: Barret Rhoden <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 init/initramfs.c |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

Patch

--- a/init/initramfs.c~initramfs-panic-with-memory-information
+++ a/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 +46,16 @@  static void __init error(char *x)
 		message = x;
 }
 
+static void panic_show_mem(const char *fmt, ...)
+{
+	va_list args;
+
+	show_mem(0, NULL);
+	va_start(args, fmt);
+	panic(fmt, args);
+	va_end(args);
+}
+
 /* link hash */
 
 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
@@ -80,7 +91,7 @@  static char __init *find_link(int major,
 	}
 	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 +136,7 @@  static void __init dir_add(const char *n
 {
 	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 +471,7 @@  static char * __init unpack_to_rootfs(ch
 	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 +618,7 @@  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;