Messages in this thread |  | | Date | Fri, 17 Nov 2000 19:11:25 +0100 | From | Andrea Arcangeli <> | Subject | Re: Memory management bug |
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On Fri, Nov 17, 2000 at 05:35:53PM +0100, schwidefsky@de.ibm.com wrote: > I did a little closer investigation. The BUG was triggered by a page with > page->mapping pointing to an address space of a mapped ext2 file > (page->mapping->a_ops == &ext2_aops). The page had PG_locked, PG_uptodate, > PG_active and PG_swap_cache set. The stack backstrace showed that kswapd > called do_try_to_free_pages, refill_inactive, swap_out, swap_out_mm, > swap_out_vma, try_to_swap_out and add_to_swap_cache where BUG hit. The > registers look good, the struct page looks good. I don't think that this was > a random memory corruption.
Agreed, that's almost sure _not_ random memory corruption of the page structure. It looks like a VM bug (if you can reproduce trivially I'd give a try to test8 too since test8 is rock solid for me while test10 lockups in VM core at the second bonnie if using emulated highmem).
> I was refering to the "if (!order) goto try_again" ifs in alloc_pages, not > the "if (something) BUG()" ifs.
Ah ok :), see Linus's answer: in your case the "don't do that" means to implement the:
#define SOFT_PAGE_SIZE (PAGE_SIZE<<2)
thing we were talking about yesterday of course.
Plus I add that the "if (!order) goto try_again" is an obvious deadlock prone bug introduce in test9 that should be removed.
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