Messages in this thread |  | | Date | Fri, 18 Jan 2013 14:44:55 +0000 | From | Christoph Lameter <> | Subject | Re: [RFC][PATCH v2] slub: Keep page and object in sync in slab_alloc_node() |
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On Thu, 17 Jan 2013, Steven Rostedt wrote:
> In slab_alloc_node(), after the cpu_slab is assigned, if the task is > preempted and moves to another CPU, there's nothing keeping the page and > object in sync. The -rt kernel crashed because page was NULL and object > was not, and the node_match() dereferences page. Even though the crash > happened on -rt, there's nothing that's keeping this from happening on > mainline. > > The easiest fix is to disable interrupts for the entire time from > acquiring the current CPU cpu_slab and assigning the object and page. > After that, it's fine to allow preemption.
Its easiest to just check for the NULL pointer as initally done. The call to __slab_alloc can do what the fastpath does.
And the fastpath will verify that the c->page pointer was not changed.
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