Date: Tue, 17 Nov 2009 10:29:03 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kosaki.motohiro@jp.fujitsu.com,
       linux-mm <linux-mm@kvack.org>,
       Andrew Morton <akpm@linux-foundation.org>, linux-mmc@vger.kernel.org
Subject: Re: [PATCH 2/7] mmc: Don't use PF_MEMALLOC
Message-ID: <20091117102903.7cb45ff3@lxorguk.ukuu.org.uk>
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	<20091117161711.3DDA.A69D9226@jp.fujitsu.com>
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On Tue, 17 Nov 2009 16:17:50 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> Non MM subsystem must not use PF_MEMALLOC. Memory reclaim need few
> memory, anyone must not prevent it. Otherwise the system cause
> mysterious hang-up and/or OOM Killer invokation.

So now what happens if we are paging and all our memory is tied up for
writeback to a device or CIFS etc which can no longer allocate the memory
to complete the write out so the MM can reclaim ?

Am I missing something or is this patch set not addressing the case where
the writeback thread needs to inherit PF_MEMALLOC somehow (at least for
the I/O in question and those blocking it)

Alan
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