Messages in this thread | | | Date | Thu, 10 Oct 2013 13:51:45 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH] mm: hugetlb: initialize PG_reserved for tail pages of gigantig compound pages |
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On 10/10/2013 12:12 PM, Andrea Arcangeli wrote: > 11feeb498086a3a5907b8148bdf1786a9b18fc55 introduced a memory leak when > KVM is run on gigantic compound pages. > > 11feeb498086a3a5907b8148bdf1786a9b18fc55 depends on the assumption > that PG_reserved is identical for all head and tail pages of a > compound page. So that if get_user_pages returns a tail page, we don't > need to check the head page in order to know if we deal with a > reserved page that requires different refcounting. > > The assumption that PG_reserved is the same for head and tail pages is > certainly correct for THP and regular hugepages, but gigantic > hugepages allocated through bootmem don't clear the PG_reserved on the > tail pages (the clearing of PG_reserved is done later only if the > gigantic hugepage is freed). > > This patch corrects the gigantic compound page initialization so that > we can retain the optimization in > 11feeb498086a3a5907b8148bdf1786a9b18fc55. The cacheline was already > modified in order to set PG_tail so this won't affect the boot time of > large memory systems. > > Reported-by: andy123 <ajs124.ajs124@gmail.com> > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
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