Messages in this thread | | | Date | Fri, 11 Sep 2009 20:07:13 +0900 | Subject | Re: [PATCH 1/8] mm: munlock use follow_page | From | Hiroaki Wakabayashi <> |
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2009/9/8 Hugh Dickins <hugh.dickins@tiscali.co.uk>: > Hiroaki Wakabayashi points out that when mlock() has been interrupted > by SIGKILL, the subsequent munlock() takes unnecessarily long because > its use of __get_user_pages() insists on faulting in all the pages > which mlock() never reached. > > It's worse than slowness if mlock() is terminated by Out Of Memory kill: > the munlock_vma_pages_all() in exit_mmap() insists on faulting in all the > pages which mlock() could not find memory for; so innocent bystanders are > killed too, and perhaps the system hangs. > > __get_user_pages() does a lot that's silly for munlock(): so remove the > munlock option from __mlock_vma_pages_range(), and use a simple loop of > follow_page()s in munlock_vma_pages_range() instead; ignoring absent > pages, and not marking present pages as accessed or dirty. > > (Change munlock() to only go so far as mlock() reached? That does not > work out, given the convention that mlock() claims complete success even > when it has to give up early - in part so that an underlying file can be > extended later, and those pages locked which earlier would give SIGBUS.) > > Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: Hiroaki Wakabayashi <primulaelatior@gmail.com>
It very simple and so cool! I have learned something.
-- Thanks, Hiroaki Wakabayashi -- 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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