Messages in this thread | | | Date | Tue, 19 Dec 2006 17:34:39 +1100 | From | Nick Piggin <> | Subject | Re: [RFC][PATCH] Fix area->nr_free-- went (-1) issue in buddy system |
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Hi Aubery!
Aubrey wrote: > Hi Nick, > > Thanks for your reply again, ;-). > > On 12/19/06, Nick Piggin <nickpiggin@yahoo.com.au> wrote: > >> >> This should not happen because the pages are checked to ensure they are >> from the same zone before merging. > > > How? page_is_buddy() only check if the buddy has the buddy flag and > has the same order. > Where can I find the same zone is checked?
Ah OK, you're using 2.6.16? Later kernels have a check for this. I guess you could backport it?
> >> >> What kind of system do you have? What is the dmesg and the .config? > > > I'm using the blackfin uclinux. dmesg and .config is attached. > >> It could be that the zones are not properly aligned and >> CONFIG_HOLES_IN_ZONE >> is not set. > > > I changed the code in paging_init(), see below: > ----------------------------------------- > #if 0 > zones_size[ZONE_DMA] = (end_mem - PAGE_OFFSET) >> > PAGE_SHIFT; > zones_size[ZONE_NORMAL] = 0; > #else > zones_size[ZONE_DMA] = (end_mem/2 - PAGE_OFFSET) >> > PAGE_SHIFT; > zones_size[ZONE_NORMAL] = (end_mem/2 - PAGE_OFFSET) >> > PAGE_SHIFT; > #endif > ----------------------------------------- > This is only what I did the change. I also suspect the zones are not > properly aligned, But how to align it? I think our system doesn't need > CONFIG_HOLES_IN_ZONE.
That's right. I guess you can either align your zone sizes (must be aligned to MAX_ORDER size), or add the zone check in page_is_buddy.
Hope that works.
Nick
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