Messages in this thread | | | Date | Tue, 16 Jun 2009 08:52:22 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 10/22] HWPOISON: check and isolate corrupted free pages v2 |
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On Mon, 15 Jun 2009 18:16:20 +0800 Wu Fengguang <fengguang.wu@intel.com> wrote:
> On Mon, Jun 15, 2009 at 05:41:12PM +0800, KAMEZAWA Hiroyuki wrote: > > On Mon, 15 Jun 2009 10:45:30 +0800 > > Wu Fengguang <fengguang.wu@intel.com> wrote: > > > > > From: Wu Fengguang <fengguang.wu@intel.com> > > > > > > If memory corruption hits the free buddy pages, we can safely ignore them. > > > No one will access them until page allocation time, then prep_new_page() > > > will automatically check and isolate PG_hwpoison page for us (for 0-order > > > allocation). > > > > > > This patch expands prep_new_page() to check every component page in a high > > > order page allocation, in order to completely stop PG_hwpoison pages from > > > being recirculated. > > > > > > Note that the common case -- only allocating a single page, doesn't > > > do any more work than before. Allocating > order 0 does a bit more work, > > > but that's relatively uncommon. > > > > > > This simple implementation may drop some innocent neighbor pages, hopefully > > > it is not a big problem because the event should be rare enough. > > > > > > This patch adds some runtime costs to high order page users. > > > > > > [AK: Improved description] > > > > > > v2: Andi Kleen: > > > Port to -mm code > > > Move check into separate function. > > > Don't dump stack in bad_pages for hwpoisoned pages. > > > > > > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> > > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > > > > > > --- > > > mm/page_alloc.c | 20 +++++++++++++++++++- > > > 1 file changed, 19 insertions(+), 1 deletion(-) > > > > > > --- sound-2.6.orig/mm/page_alloc.c > > > +++ sound-2.6/mm/page_alloc.c > > > @@ -233,6 +233,12 @@ static void bad_page(struct page *page) > > > static unsigned long nr_shown; > > > static unsigned long nr_unshown; > > > > > > + /* Don't complain about poisoned pages */ > > > + if (PageHWPoison(page)) { > > > + __ClearPageBuddy(page); > > > + return; > > > + } > > > > Hmm ? why __ClearPageBuddy() is necessary ? > > Because this page is considered to be "allocated" out of the buddy > system, even though we fail the allocation here. > > The page is now owned by no one, especially not owned by the buddy > allocator. > I just wonder "why __ClearPageBuddy() is necessary."
When bad_page() is called, a page is removed from buddy allocator and no PG_buddy flag at all....I'm sorry if you added bad_page() caller in buddy allocator.
Buddy Allocator I call here is just 2 functions. - __free_one_page() - expand()
Bye, -Kame
> Thanks, > Fengguang >
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