On Tue, Oct 10, 2006 at 04:34:40PM -0700, Chen, Kenneth W wrote:
> Hugh Dickins wrote on Tuesday, October 10, 2006 12:18 PM
> > Yes, I'd expect your i_mmap_lock to solve the problem: and since
> > you're headed in that direction anyway, it makes most sense to use
> > that solution rather than get into defining arrays, or sacrificing
> > the lazy flush, or risking page_count races.
> >
> > So please extract the __unmap_hugepage_range mods from your shared
> > pagetable patch, and use that to fix the bug.
>
>
> OK, here is a bug fix patch fixing earlier "bug fix" patch :-(
>
>
> [patch] hugetlb: fix linked list corruption in unmap_hugepage_range
>
> commit fe1668ae5bf0145014c71797febd9ad5670d5d05 causes kernel to oops with
> libhugetlbfs test suite. The problem is that hugetlb pages can be shared
> by multiple mappings. Multiple threads can fight over page->lru in the unmap
> path and bad things happen. We now serialize __unmap_hugepage_range to void
> concurrent linked list manipulation. Such serialization is also needed for
> shared page table page on hugetlb area. This patch will fixed the bug and
> also serve as a prepatch for shared page table.
Can I suggest that you put a big comment on the linked list
declaration itself saying that you're relying on serialization here.
Otherwise I'm worried someone will try to de-serialize it again, and
break it without realizing. Given the number of people who failed to
spot the problem with the patch the first time around..
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
