Messages in this thread | | | Date | Tue, 24 Apr 2007 10:51:47 -0700 | From | Andrew Morton <> | Subject | Re: Pagecache: find_or_create_page does not call a proper page allocator function |
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On Tue, 24 Apr 2007 18:45:03 +0100 (BST) Hugh Dickins <hugh@veritas.com> wrote:
> On Tue, 24 Apr 2007, Christoph Lameter wrote: > > On Tue, 24 Apr 2007, Hugh Dickins wrote: > > > > > I've not yet looked at the patch under discussion, but this remark > > > prompts me... a couple of days ago I got very worried by the various > > > hard-wired GFP_HIGHUSER allocations in mm/migrate.c and mm/mempolicy.c, > > > and wondered how those would work out if someone has a blockdev mmap'ed. > > > > Hmmm.... These not that critical given that 32 bit NUMA systems are a bit > > rare. > > That's true. And everybody but the owners of those systems wish > fervently that they didn't exist ;) > > > And if a page is in the wrong area then it can be bounced before I/O > > is performed on it. > > I think that much is also true, but not where the problem lies. > Isn't the problem that filesystems using these block devices > expect their metadata to be accessible without kmap calls? >
yup. wherever we dereference buffer_head.b_data we're touching page_address(buffer_head.b_page) without kmapping. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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