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Date:      Mon, 18 Jan 1999 14:33:18 -0800
From:      Mike Smith <mike@smith.net.au>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        current@FreeBSD.ORG
Subject:   Re: kernel malloc and M_CANWAIT 
Message-ID:  <199901182233.OAA19242@dingo.cdrom.com>
In-Reply-To: Your message of "Tue, 19 Jan 1999 09:11:38 %2B1100." <199901182211.JAA17726@godzilla.zeta.org.au> 

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> >    If the system is simply low on memory, kmem_malloc() will block.
> >
> >    So malloc() will generally not return NULL even in low memory situations
> >    unless the KVM map fills up, which isn't supposed to happen but can in
> >    certain severe circumstances.  Callers should therefore check for NULL.
> 
> Callers that check for NULL are bogus. 

If it can truly never return NULL, that's true.  But it would also be 
true to say that callers that can't deal with a veto return and that 
can't guarantee deadlock avoidance are also bogus.

I got the impression that my understanding of M_WAITOK's behaviour 
came from a discussion with you about it, but it looks like I was 
mistaken.

-- 
\\  Sometimes you're ahead,       \\  Mike Smith
\\  sometimes you're behind.      \\  mike@smith.net.au
\\  The race is long, and in the  \\  msmith@freebsd.org
\\  end it's only with yourself.  \\  msmith@cdrom.com



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