Messages in this thread |  | | | Date | Sat, 19 Nov 2011 11:26:59 +0800 | | Subject | Re: [PATCH] hugetlb: detect race if fail to COW | | From | Hillf Danton <> |
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On Sat, Nov 19, 2011 at 3:39 AM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Fri, 18 Nov 2011 17:11:28 +0100 > Michal Hocko <mhocko@suse.cz> wrote: > >> On Fri 18-11-11 23:23:12, Hillf Danton wrote: >> > On Fri, Nov 18, 2011 at 11:07 PM, Michal Hocko <mhocko@suse.cz> wrote: >> > > On Fri 18-11-11 22:04:37, Hillf Danton wrote: >> > >> In the error path that we fail to allocate new huge page, before try again, we >> > >> have to check race since page_table_lock is re-acquired. >> > > >> > > I do not think we can race here because we are serialized by >> > > hugetlb_instantiation_mutex AFAIU. Without this lock, however, we could >> > > fall into avoidcopy and shortcut despite the fact that other thread has >> > > already did the job. >> > > >> > > The mutex usage is not obvious in hugetlb_cow so maybe we want to be >> > > explicit about it (either a comment or do the recheck). >> > > >> > >> > Then the following check is unnecessary, no? >> >> Hmm, thinking about it some more, I guess we have to recheck because we >> can still race with page migration. So we need you patch. >> >> Reviewed-by: Michal Hocko <mhocko@suse.cz> > > So we need a new changelog. How does this look? > Thanks Andrew and Michal:)
Best regards Hillf -- 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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