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Re: patch to give kmalloc a chance (RFC)

To: Steve Lord <lord@xxxxxxx>
Subject: Re: patch to give kmalloc a chance (RFC)
From: Andrew Morton <akpm@xxxxxxxxx>
Date: Fri, 27 Sep 2002 15:52:28 -0700
Cc: Ravi Wijayaratne <ravi_wija@xxxxxxxxx>, linux-xfs@xxxxxxxxxxx, Eric Sandeen <sandeen@xxxxxxx>, riel@xxxxxxxxxxxxxxxxxxxxxxxxx
References: <20020927215041.77738.qmail@web40614.mail.yahoo.com> <1033163688.10533.79.camel@jen.americas.sgi.com>
Sender: linux-xfs-bounce@xxxxxxxxxxx
Steve Lord wrote:
> 
> I am picturing Rik with shivers going down his spine right now ;-)
> 

Take a look at __jbd_kmalloc() ;)

For a NOFS allocation, simply retrying is a crude-but-effective
fix.  We have kicked kswapd and kswapd _does_ have __GFP_FS.

So things work out, as long as the filesystem doesn't hold locks which
would prevent kswapd from being able to reclaim some memory.

It's not just a lock ordering thing either - the GFP_NOFS allocator
is not able to use the traditional IO-based throttling.  It's
probably just that there's plenty of writeback in flight but the
allocator needs to be more patient.


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