Messages in this thread | | | Subject | Re: SLUB doesn't work with kdump kernel on Cell | From | Lucio Correia <> | Date | Tue, 14 Aug 2007 12:43:59 -0300 |
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On Wed, 2007-08-08 at 13:26 -0700, Christoph Lameter wrote: > On Wed, 8 Aug 2007, Lucio Correia wrote: > > > Hi Christoph, > > > > I found a problem with SLUB when trying to boot a kdump kernel on a Cell > > QS20 Blade running Fedora 7, kernel 2.6.22.5. If I use SLAB for the > > kdump kernel, everything works ok. The fact is that SLUB doesn't find a > > page frame for allocation in the current node, due to the flag > > GFP_THISNODE on a call to new_slab, and stops at a BUG_ON on line 1802 > > of slub.c. > > This is due to the node 1 having only one page. Could you just switch node > 1 off? > > SLAB boots because it falls back to node 0 for the control structures. So > it creates useless control structures for node 1. These are then never > used since any allocation attempt to node 1 falls back to node 0.
Hi Christoph,
Shouldn't SLUB falls back to other node also for the case it can't allocate memory?
> > > I understand that this flag should not be removed, and that there is a > > better solution, but it demonstrates the problem. Could you give me some > > direction on the better way to solve this problem? > > Do not create a node that just has one page in it? > > Or make it truly empty? An empty node will cause GFP_THISNODE to fall back > and you then have the same useless control structure allocation as on > SLAB.
-- Lucio Correia Software Engineer IBM LTC Brazil
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