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Subject: Re: [PATCH]: Remove PF_MEMDIE as it is redundant
From: Robert Love <rml@tech9.net>
To: Juan Quintela <quintela@mandrakesoft.com>
Cc: Marcelo Tosatti <marcelo@conectiva.com.br>,
       Andrea Arcangeli <andrea@suse.de>, lkml <linux-kernel@vger.kernel.org>
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On Wed, 2003-01-08 at 18:49, Juan Quintela wrote:

> That is a nice theory, and I think that this could be true in the
> past, but in 2.4.2X, PF_MEMDIE only appears in the two places that I
> show, and it is completely redundant, look at the patch, we are just 
> |-ing both PF_MEMALLOC and PF_MEMDIE and later we are &-ing against
> the or of the two.  Use find & grep yourself if you don't believe me.

I realize this.

The issue is that PF_MEMALLOC can be _cleared_.  In that case, if you
only set PF_MEMALLOC, that check can be false when we want it true.  So
we need a flag that is more persistent.

PF_MEMDIE, which is not cleared on various allocation paths in the VM,
ensures that the check holds true for all OOM'ed tasks.

I thought the same as you, "hey this thing is worthless let us dump it",
and Rik and Andrew told me otherwise.

I am not saying you are wrong, though - I could be very wrong.  But my
point is not what you say above; it is that the flag is needed because
just setting PF_MEMALLOC is insufficient since it can be unset.

	Robert Love


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