Messages in this thread | | | Date | Wed, 17 Jun 2009 09:28:26 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH 09/22] HWPOISON: Handle hardware poisoned pages in try_to_unmap |
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On Tue, 16 Jun 2009 21:49:44 +0800 Wu Fengguang <fengguang.wu@intel.com> wrote:
> On Tue, Jun 16, 2009 at 08:03:08AM +0800, Minchan Kim wrote: > > On Mon, 15 Jun 2009 23:26:12 +0800 > > Wu Fengguang <fengguang.wu@intel.com> wrote: > > > > > On Mon, Jun 15, 2009 at 09:09:03PM +0800, Minchan Kim wrote: > > > > On Mon, Jun 15, 2009 at 11:45 AM, Wu Fengguang<fengguang.wu@intel.com> wrote: > > > > > From: Andi Kleen <ak@linux.intel.com> > > > > > > > > > > When a page has the poison bit set replace the PTE with a poison entry. > > > > > This causes the right error handling to be done later when a process runs > > > > > into it. > > > > > > > > > > Also add a new flag to not do that (needed for the memory-failure handler > > > > > later) > > > > > > > > > > Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> > > > > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > > > > > > > > > > --- > > > > > include/linux/rmap.h | 1 + > > > > > mm/rmap.c | 9 ++++++++- > > > > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > > > > > > > --- sound-2.6.orig/mm/rmap.c > > > > > +++ sound-2.6/mm/rmap.c > > > > > @@ -958,7 +958,14 @@ static int try_to_unmap_one(struct page > > > > > /* Update high watermark before we lower rss */ > > > > > update_hiwater_rss(mm); > > > > > > > > > > - if (PageAnon(page)) { > > > > > + if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { > > > > > + if (PageAnon(page)) > > > > > + dec_mm_counter(mm, anon_rss); > > > > > + else if (!is_migration_entry(pte_to_swp_entry(*pte))) > > > > > > > > Isn't it straightforward to use !is_hwpoison_entry ? > > > > > > Good catch! It looks like a redundant check: the > > > page_check_address() at the beginning of the function guarantees that > > > !is_migration_entry() or !is_migration_entry() tests will all be TRUE. > > > So let's do this? > > It seems you expand my sight :) > > > > I don't know migration well. > > How page_check_address guarantee it's not migration entry ? > > page_check_address() calls pte_present() which returns the > (_PAGE_PRESENT | _PAGE_PROTNONE) bits. While x86-64 defines > > #define __swp_entry(type, offset) ((swp_entry_t) { \ > ((type) << (_PAGE_BIT_PRESENT + 1)) \ > | ((offset) << SWP_OFFSET_SHIFT) }) > > where SWP_OFFSET_SHIFT is defined to the bigger one of > max(_PAGE_BIT_PROTNONE + 1, _PAGE_BIT_FILE + 1) = max(8+1, 6+1) = 9. > > So __swp_entry(type, offset) := (type << 1) | (offset << 9) > > We know that the swap type is 5 bits. So the bit 0 _PAGE_PRESENT and bit 8 > _PAGE_PROTNONE will all be zero for swap entries. >
Thanks for kind explanation :)
> > > In addtion, If the page is poison while we are going to > > migration((PAGE_MIGRATION && migration) == TRUE), we should decrease > > file_rss ? > > It will die on trying to migrate the poisoned page so we don't care > the accounting. But normally the poisoned page shall already be
Okay. then, how about this ? We should not increase file_rss on trying to migrate the poisoned page
- else if (!is_migration_entry(pte_to_swp_entry(*pte))) + else if (!(PAGE_MIGRATION && migration))
> isolated so we don't care that die either. > Thanks, > Fengguang > > > > > > > - else if (!is_migration_entry(pte_to_swp_entry(*pte))) > > > + else > > > > > > > > > Thanks, > > > Fengguang > > > > > > -- > > Kinds Regards > > Minchan Kim
-- Kinds Regards Minchan Kim -- 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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