Re: [PATCH] x86: endless page faults in mount_block_root for Linux 2.6

Ingo Molnar
2008-04-29T14:34:20Z

* Henry Nestler <Henry.Ne@Arcor.de> wrote:

> I'm not shure with the VFS fix. The change only has effect for x86 and
> x86_64. I'm afraid. Mostly other architectures no need to change. I
> would only public the base of the problem. Perhaps no need to change
> here.

btw., i have a kmemcheck-reported bug fixed in this same area with the
patch below. I dont remember the details anymore, but the root mount
code did something really, really weird here.

Ingo

------------>
Subject: init: root mount fix
From: Ingo Molnar <mingo@elte.hu>
Date: Tue Apr 29 16:31:50 CEST 2008

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
init/do_mounts.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

Index: linux/init/do_mounts.c
===================================================================
--- linux.orig/init/do_mounts.c
+++ linux/init/do_mounts.c
@@ -201,9 +201,13 @@ static int __init do_mount_root(char *na
return 0;
}

+#if PAGE_SIZE < PATH_MAX
+# error increase the fs_names allocation size here
+#endif
+
void __init mount_block_root(char *name, int flags)
{
- char *fs_names = __getname();
+ char *fs_names = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
char *p;
#ifdef CONFIG_BLOCK
char b[BDEVNAME_SIZE];
@@ -251,7 +255,7 @@ retry:
#endif
panic("VFS: Unable to mount root fs on %s", b);
out:
- putname(fs_names);
+ free_pages((unsigned long)fs_names, 1);
}

#ifdef CONFIG_ROOT_NFS