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List:       freebsd-hackers
Subject:    Re: pwd.db corruption
From:       Matthew Dillon <dillon () apollo ! backplane ! com>
Date:       1999-01-31 5:15:06
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:> I'm running a machine with FreeBSD 2.2.2-RELEASE and about 4 times now, the
:> pwd.db file has become corrupt. When this happens, it wont authenticate
:> anyone, and I have to reboot into single user mode, remove the pwd.db
:> (rename it to pwd.old basically), and add a new user. After a reboot, it is
:...
:
:This is a known bug, having to do with the reclaim of mmap'ed pages
:and their reuse before they have been disaaciated from all of the
:objects that reference them.
:
:The problem is exacerbated by cron, which modifies the return values
:in the read-only pages pointed to by the static struct passwd that's
:passed back (they point into the entries in the passwd database).
:After the COW fault on the pages, they tend to get written back after
:a reclaim.
:
:I most frequently see this as a corrupt crontab; it really depends
:on what's running and what file is having pages thrashed in and out
:of core.
:
:Upgrading to 4.0-current appears to fix this.
:
:There are a number of bugs in 3.0 that aren't in the 3.0-stable
:branch; a shirt tail relative of this bug os one of them.
:
:The 4.0 fixes that haven't been back-ported to 3.0-STABLE are
:probably enough, at this point, to justify using 4.0.
:
:
:					Terry Lambert
:					terry@lambert.org

    Hmm. If you recall the general area of the bug fix related to 
    this problem I can research it.  *All* VM bugs fixed in 4.x
    should have already been backported to 3.x, but a few sometimes
    get missed ( e.g. like that NFS corruption bug fix ).

					Matthew Dillon 
					<dillon@backplane.com>

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