Messages in this thread | | | Date | Wed, 04 Feb 2009 17:31:27 +0800 | From | Miao Xie <> | Subject | Re: [PATCH] cpuset: fix allocating page cache/slab object on the unallowed node when memory spread is set |
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on 2009-2-4 6:49 Paul Menage wrote: > On Tue, Feb 3, 2009 at 2:16 PM, Andrew Morton <akpm@linux-foundation.org> wrote: >> On Tue, 03 Feb 2009 11:25:25 +0800 >> Miao Xie <miaox@cn.fujitsu.com> wrote: [snip] >> >> I wasn't able to find out where the setting of init'smems_allowed >> happens, after a bit of grepping and hunting. It should be done within >> INIT_TASK, but isn't. >> >> Still, kthreadd is reliably parented by swapper, and there shold be no >> need to alter its mems_allowed. >> >> Similarly, what was the reason for setting current->mems_allowed in >> kernel_init()? That also should be unneeded. >> >> Finally, I've somewhat lost track of where we are with this patch. >> Paul, do you see any other remaining issues? > > AFAICS this patch still has a race between a thread reading its > mems_allowed, and another thread updating it. The current architecture > of having task->mems_allowed be only updatable by current was PaulJ's > code originally, and I'm a bit loathe to touch it. But if we're going > to, we'll need at the minimum to add a lock for any code that touches > current->mems_allowed.
Agree! But mems_allowed is touched in the module of memory management in general, adding a lock to protect mems_allowed may lead to performance regression.
> > Paul > > >
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