Commit 42d623a8 authored Nov 23, 2011 by Christoph Lameter Committed by Pekka Enberg Nov 24, 2011

slub: use irqsafe_cpu_cmpxchg for put_cpu_partial

The cmpxchg must be irq safe. The fallback for this_cpu_cmpxchg only
disables preemption which results in per cpu partial page operation
potentially failing on non x86 platforms.

This patch fixes the following problem reported by Christian Kujau:

  I seem to hit it with heavy disk & cpu IO is in progress on this
  PowerBook
  G4. Full dmesg & .config: http://nerdbynature.de/bits/3.2.0-rc1/oops/

  I've enabled some debug options and now it really points to slub.c:2166

    http://nerdbynature.de/bits/3.2.0-rc1/oops/oops4m.jpg



  With debug options enabled I'm currently in the xmon debugger, not sure
  what to make of it yet, I'll try to get something useful out of it :)

Reported-by: Christian Kujau <lists@nerdbynature.de>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

parent 9ada1934

mm/slub.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1978,7 +1978,7 @@ int put_cpu_partial(struct kmem_cache s, struct page page, int drain)
		page->pobjects = pobjects;
		page->next = oldpage;

		} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage);
		} while (irqsafe_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage);
		stat(s, CPU_PARTIAL_FREE);
		return pobjects;
		}

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