Messages in this thread Patch in this message | | | Date | Thu, 13 Jul 2006 09:38:38 +0200 | From | Jan Kiszka <> | Subject | Re: [PATCH] mm: fix oom roll-back of __vmalloc_area_node |
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Andrew Morton wrote:
> On Tue, 11 Jul 2006 21:37:08 +0200 > Jan Kiszka <jan.kiszka@web.de> wrote: > > >> __vunmap must not rely on area->nr_pages when picking the >> release methode for area->pages. It may be too small when >> __vmalloc_area_node failed early due to lacking memory. >> Instead, use a flag in vmstruct to differentiate. >> > > So you mean that when this: > > if (unlikely(!area->pages[i])) { > /* Successfully allocated i pages, free them in __vunmap() */ > area->nr_pages = i; > goto fail; > > happens, it could be that i <= PAGE_SIZE/sizeof(struct page *) and __vunmap > kfree()s something which it should have vfree()d, yes? > >
Yes, exactly. It then causes some BUG in kfree during unroll.
> That sounds like a dead box, or worse. > > Someone triggered a too large vmalloc request, that was the scenario here.
> I think the change would be a good one even if it didn't fix a bug, thanks. > > Meanwhile I thought about an even simpler solution:
__vunmap must not rely on area->nr_pages when picking the release methode for area->pages. It may be too small when __vmalloc_area_node failed due to lacking memory. Check for the vmalloc address range instead.
Signed-off by: Jan Kiszka <jan.kiszka@web.de>
Index: linux-2.6/mm/vmalloc.c =================================================================== --- linux-2.6.orig/mm/vmalloc.c +++ linux-2.6/mm/vmalloc.c @@ -340,7 +340,7 @@ void __vunmap(void *addr, int deallocate __free_page(area->pages[i]); } - if (area->nr_pages > PAGE_SIZE/sizeof(struct page *)) + if (area->pages >= VMALLOC_START && area->pages < VMALLOC_END) vfree(area->pages); else kfree(area->pages);
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