Messages in this thread | | | Date | Wed, 25 Jun 2014 08:29:04 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: [PATCH 2/2] x86,mem-hotplug: modify PGD entry when removing memory |
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(2014/06/25 0:12), Toshi Kani wrote: > On Tue, 2014-06-24 at 09:31 +0900, Yasuaki Ishimatsu wrote: >> (2014/06/21 3:30), Toshi Kani wrote: >>> On Wed, 2014-06-18 at 15:38 +0900, Yasuaki Ishimatsu wrote: >>> : >>>> @@ -186,7 +186,12 @@ void sync_global_pgds(unsigned long start, unsigned long end) >>>> const pgd_t *pgd_ref = pgd_offset_k(address); >>>> struct page *page; >>>> >>>> - if (pgd_none(*pgd_ref)) >>>> + /* >>>> + * When it is called after memory hot remove, pgd_none() >>>> + * returns true. In this case (removed == 1), we must clear >>>> + * the PGD entries in the local PGD level page. >>>> + */ >>>> + if (pgd_none(*pgd_ref) && !removed) >>>> continue; >>>> >>>> spin_lock(&pgd_lock); >>>> @@ -199,12 +204,18 @@ void sync_global_pgds(unsigned long start, unsigned long end) >>>> pgt_lock = &pgd_page_get_mm(page)->page_table_lock; >>>> spin_lock(pgt_lock); >>>> >>>> - if (pgd_none(*pgd)) >>>> - set_pgd(pgd, *pgd_ref); >>>> - else >> >>>> + if (!pgd_none(*pgd_ref) && !pgd_none(*pgd)) >>>> BUG_ON(pgd_page_vaddr(*pgd) >>>> != pgd_page_vaddr(*pgd_ref)); >>>> >>>> + if (removed) { >>> >>> Shouldn't this condition be "else if"? >> >> The first if sentence checks whether PGDs hit to BUG_ON. And the second >> if sentence checks whether the function was called after hot-removing memory. >> I think that the first if sentence and the second if sentence check different >> things. So I think the condition should be "if" sentence. > > When the 1st if sentence is true, you have no additional operation and > the 2nd if sentence is redundant. But I agree that the two ifs can be > logically separated. So: >
> Acked-by: Toshi Kani <toshi.kani@hp.com>
Thank you for your review.
Thanks, Yasuaki Ishimatsu
> > Thanks, > -Toshi >
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