Messages in this thread | | | Date | Thu, 22 Apr 2010 09:11:04 +0900 | Subject | Re: [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages | From | Minchan Kim <> |
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On Thu, Apr 22, 2010 at 8:59 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > On Wed, 21 Apr 2010 09:30:20 -0500 (CDT) > Christoph Lameter <cl@linux-foundation.org> wrote: > >> On Tue, 20 Apr 2010, Mel Gorman wrote: >> >> > @@ -520,10 +521,12 @@ static int move_to_new_page(struct page *newpage, struct page *page) >> > else >> > rc = fallback_migrate_page(mapping, newpage, page); >> > >> > - if (!rc) >> > - remove_migration_ptes(page, newpage); >> > - else >> > + if (rc) { >> > newpage->mapping = NULL; >> > + } else { >> > + if (remap_swapcache) >> > + remove_migration_ptes(page, newpage); >> > + } >> >> You are going to keep the migration ptes after the page has been unlocked? >> Or is remap_swapcache true if its not a swapcache page? >> >> Maybe you meant >> >> if (!remap_swapcache) >> > > Ah....Can I confirm my understanding ? > > remap_swapcache == true only when > The old page was ANON && it is not mapped. && it is SwapCache. > > We do above check under lock_page(). So, this SwapCache is never mapped until > we release lock_page() on the old page. So, we don't use migration_pte in > this case because try_to_unmap() do nothing and don't need to call > remove_migration_pte().
Yes. so I thought what kinds of race happened. Firstly I doubt fork and migration. but It isn't. I can't understand how this bug happens. Apparently, We have been missed something. I will look into this further.
-- Kind 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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