On Tue, 9 May 2000, Tigran Aivazian wrote:
> Hi Alexander,
>
> Are you sure that proc_pid_readlink() needs those dput()/mntput(), since
> sys_readlink() does dput()/mntput() them anyway?
HUH? It does, but for completely different object.
> This patch fixes the old "lsof(8) causes oops in 2.3.99-pre7-8" problem
> but I was not 100% sure in its correctness (i.e. there must have been some
> reason for dput/mntput in proc_pid_readlink?) so I did not send it to
> Linus. Comments, please?
It's incorrect. However, there actually _is_ a problem in proc_pid_readlink()
and I wonder how came that it didn't bite us before. Try the following
and see if it helps:
--- ../../../2.3.99-pre7-8/fs/proc/base.c Tue May 9 11:27:28 2000
+++ base.c Tue May 9 11:34:04 2000
@@ -446,18 +446,19 @@
{
int error;
struct inode *inode = dentry->d_inode;
+ struct dentry *de;
struct vfsmount *mnt;
error = proc_permission(inode, MAY_EXEC);
if (error)
goto out;
- error = inode->u.proc_i.op.proc_get_link(inode, &dentry, &mnt);
+ error = inode->u.proc_i.op.proc_get_link(inode, &de, &mnt);
if (error)
goto out;
- error = do_proc_readlink(dentry, mnt, buffer, buflen);
- dput(dentry);
+ error = do_proc_readlink(de, mnt, buffer, buflen);
+ dput(de);
mntput(mnt);
out:
... and yes, I feel myself like an idiot, why are you asking?
Al
>
> Also, although lsof now works, /proc still (with or without patch ) cannot
> be umounted (even without any apparent references to it) so one should
> still investigate a bit further and see what keeps it busy.. (I will try
> and look into it now, unless you confirm that the reasons are known and
> elsewhere)
>
> Regards,
> Tigran
>
> --- linux/fs/proc/base.c Tue May 9 08:40:26 2000
> +++ work/fs/proc/base.c Tue May 9 16:06:05 2000
> @@ -457,8 +457,6 @@
> goto out;
>
> error = do_proc_readlink(dentry, mnt, buffer, buflen);
> - dput(dentry);
> - mntput(mnt);
> out:
> return error;
> }
>
>
>
>
> -
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