Messages in this thread Patch in this message |  | | Date | Thu, 15 Feb 2007 14:39:48 -0800 (PST) | From | Christoph Lameter <> | Subject | Re: 2.6.20-mm1 [kernel BUG at mm/swap.c:442] |
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On Thu, 15 Feb 2007, Andrew Morton wrote:
> I don't immediately see why that code isn't racy: the page can remain > in the pagevec for arbitrary amounts of time and someone can come along > and mlock it again. But given the ease with which you're hitting this, > it may not be a race.
As long as the page is on the pagevec it should be off the LRU. Marking a page PageMlocked requires the page to be on the LRU. So a page cannot be marked PageMlocked as long as it is on the regular pagevecs.
Somehow a page off the LRU was marked PageMlocked. Or a new anonymous page was allocated and marked PageMlocked and then some later processing put it onto the LRU?
Maybe try_to_set_mlocked does work some havoc here.
Could you see if this patch fixes it? This just disabled an optimization to set PageMlocked early.
Index: linux-2.6.20-mm1/mm/memory.c =================================================================== --- linux-2.6.20-mm1.orig/mm/memory.c 2007-02-15 14:35:41.000000000 -0800 +++ linux-2.6.20-mm1/mm/memory.c 2007-02-15 14:35:54.000000000 -0800 @@ -930,6 +930,8 @@ static void try_to_set_mlocked(struct pa struct zone *zone; unsigned long flags; + return; + if (!PageLRU(page) || PageMlocked(page)) return; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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