Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/kernel/traps_32.c |    1 +
 arch/x86/kernel/traps_64.c |    1 +
 fs/sysfs/file.c            |   13 +++++++++++++
 fs/sysfs/mount.c           |    2 +-
 fs/sysfs/sysfs.h           |    1 +
 include/linux/sysfs.h      |    5 +++++
 6 files changed, 22 insertions(+), 1 deletion(-)

diff -puN arch/x86/kernel/traps_32.c~gregkh-driver-sysfs-crash-debugging arch/x86/kernel/traps_32.c
--- a/arch/x86/kernel/traps_32.c~gregkh-driver-sysfs-crash-debugging
+++ a/arch/x86/kernel/traps_32.c
@@ -403,6 +403,7 @@ int __kprobes __die(const char *str, str
 #endif
 	printk("\n");
 
+	sysfs_printk_last_file();
 	if (notify_die(DIE_OOPS, str, regs, err,
 			current->thread.trap_no, SIGSEGV) != NOTIFY_STOP) {
 
diff -puN arch/x86/kernel/traps_64.c~gregkh-driver-sysfs-crash-debugging arch/x86/kernel/traps_64.c
--- a/arch/x86/kernel/traps_64.c~gregkh-driver-sysfs-crash-debugging
+++ a/arch/x86/kernel/traps_64.c
@@ -573,6 +573,7 @@ int __kprobes __die(const char * str, st
 	printk("DEBUG_PAGEALLOC");
 #endif
 	printk("\n");
+	sysfs_printk_last_file();
 	if (notify_die(DIE_OOPS, str, regs, err, current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
 		return 1;
 	show_registers(regs);
diff -puN fs/sysfs/file.c~gregkh-driver-sysfs-crash-debugging fs/sysfs/file.c
--- a/fs/sysfs/file.c~gregkh-driver-sysfs-crash-debugging
+++ a/fs/sysfs/file.c
@@ -16,10 +16,18 @@
 #include <linux/poll.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/limits.h>
 #include <asm/uaccess.h>
 
 #include "sysfs.h"
 
+/* used in crash dumps to help with debugging */
+static char last_sysfs_file[PATH_MAX];
+void sysfs_printk_last_file(void)
+{
+	printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file);
+}
+
 /*
  * There's one sysfs_buffer for each open file and one
  * sysfs_open_dirent for each sysfs_dirent with one or more open
@@ -320,6 +328,11 @@ static int sysfs_open_file(struct inode 
 	struct sysfs_buffer *buffer;
 	struct sysfs_ops *ops;
 	int error = -EACCES;
+	char *p;
+
+	p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file));
+	if (p)
+		memmove(last_sysfs_file, p, strlen(p) + 1);
 
 	/* need attr_sd for attr and ops, its parent for kobj */
 	if (!sysfs_get_active_two(attr_sd))
diff -puN fs/sysfs/mount.c~gregkh-driver-sysfs-crash-debugging fs/sysfs/mount.c
--- a/fs/sysfs/mount.c~gregkh-driver-sysfs-crash-debugging
+++ a/fs/sysfs/mount.c
@@ -22,7 +22,7 @@
 /* Random magic number */
 #define SYSFS_MAGIC 0x62656572
 
-static struct vfsmount *sysfs_mount;
+struct vfsmount *sysfs_mount;
 struct super_block * sysfs_sb = NULL;
 struct kmem_cache *sysfs_dir_cachep;
 
diff -puN fs/sysfs/sysfs.h~gregkh-driver-sysfs-crash-debugging fs/sysfs/sysfs.h
--- a/fs/sysfs/sysfs.h~gregkh-driver-sysfs-crash-debugging
+++ a/fs/sysfs/sysfs.h
@@ -91,6 +91,7 @@ struct sysfs_addrm_cxt {
 extern struct sysfs_dirent sysfs_root;
 extern struct super_block *sysfs_sb;
 extern struct kmem_cache *sysfs_dir_cachep;
+extern struct vfsmount *sysfs_mount;
 
 /*
  * dir.c
diff -puN include/linux/sysfs.h~gregkh-driver-sysfs-crash-debugging include/linux/sysfs.h
--- a/include/linux/sysfs.h~gregkh-driver-sysfs-crash-debugging
+++ a/include/linux/sysfs.h
@@ -113,6 +113,7 @@ void sysfs_remove_file_from_group(struct
 			const struct attribute *attr, const char *group);
 
 void sysfs_notify(struct kobject *kobj, char *dir, char *attr);
+void sysfs_printk_last_file(void);
 
 extern int __must_check sysfs_init(void);
 
@@ -213,6 +214,10 @@ static inline int __must_check sysfs_ini
 	return 0;
 }
 
+static inline void sysfs_printk_last_file(void)
+{
+}
+
 #endif /* CONFIG_SYSFS */
 
 #endif /* _SYSFS_H_ */
_