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Date: Thu, 19 Sep 2002 21:16:23 +0100
From: Matthew Wilcox <willy@debian.org>
To: Burton Windle <bwindle@fint.org>
Cc: linux-kernel@vger.kernel.org, Stephen Rothwell <sfr@canb.auug.org.au>,
       linux-fsdevel@vger.kernel.org
Subject: Re: [2.5.36] oops when reading /proc/locks
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[note: please cc me or linux-fsdevel when reporting file locking bugs;
i only read linux-kernel on the web and as time permits]

It looks to me like your dereference comes from this line:

        if (fl->fl_file != NULL)
                inode = fl->fl_file->f_dentry->d_inode;

and, if my terribly weak x86 assembler isn't deceiving me, f_dentry
is NULL.  Since you can reproduce this at will, could you insert some
debugging for me?

	if (fl->fl_file != NULL) {
		if (fl->fl_file->f_dentry) {
			inode = fl->fl_file->f_dentry->d_inode;
		} else {
			printk(KERN_EMERG "null dentry at %d\n", id);
		}
	}

That will avoid the oops, and tell us who managed to set a file lock on
a file without a dentry.

-- 
Revolutions do not require corporate support.
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