Messages in this thread | | | Date | Tue, 11 Sep 2012 11:24:55 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: [RFC v9 PATCH 05/21] memory-hotplug: check whether memory is present or not |
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Hi Wen,
2012/09/11 11:15, Wen Congyang wrote: > Hi, ishimatsu > > At 09/05/2012 05:25 PM, wency@cn.fujitsu.com Wrote: >> From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> >> >> If system supports memory hot-remove, online_pages() may online removed pages. >> So online_pages() need to check whether onlining pages are present or not. > > Because we use memory_block_change_state() to hotremoving memory, I think > this patch can be removed. What do you think?
Pleae teach me detals a little more. If we use memory_block_change_state(), does the conflict never occur? Why?
Thansk, Yasuaki Ishimatsu
> Thanks > Wen Congyang > >> >> CC: David Rientjes <rientjes@google.com> >> CC: Jiang Liu <liuj97@gmail.com> >> CC: Len Brown <len.brown@intel.com> >> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> >> CC: Paul Mackerras <paulus@samba.org> >> CC: Christoph Lameter <cl@linux.com> >> Cc: Minchan Kim <minchan.kim@gmail.com> >> CC: Andrew Morton <akpm@linux-foundation.org> >> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> >> CC: Wen Congyang <wency@cn.fujitsu.com> >> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> >> --- >> include/linux/mmzone.h | 19 +++++++++++++++++++ >> mm/memory_hotplug.c | 13 +++++++++++++ >> 2 files changed, 32 insertions(+), 0 deletions(-) >> >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index 2daa54f..ac3ae30 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -1180,6 +1180,25 @@ void sparse_init(void); >> #define sparse_index_init(_sec, _nid) do {} while (0) >> #endif /* CONFIG_SPARSEMEM */ >> >> +#ifdef CONFIG_SPARSEMEM >> +static inline int pfns_present(unsigned long pfn, unsigned long nr_pages) >> +{ >> + int i; >> + for (i = 0; i < nr_pages; i++) { >> + if (pfn_present(pfn + i)) >> + continue; >> + else >> + return -EINVAL; >> + } >> + return 0; >> +} >> +#else >> +static inline int pfns_present(unsigned long pfn, unsigned long nr_pages) >> +{ >> + return 0; >> +} >> +#endif /* CONFIG_SPARSEMEM*/ >> + >> #ifdef CONFIG_NODES_SPAN_OTHER_NODES >> bool early_pfn_in_nid(unsigned long pfn, int nid); >> #else >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index 49f7747..299747d 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -467,6 +467,19 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages) >> struct memory_notify arg; >> >> lock_memory_hotplug(); >> + /* >> + * If system supports memory hot-remove, the memory may have been >> + * removed. So we check whether the memory has been removed or not. >> + * >> + * Note: When CONFIG_SPARSEMEM is defined, pfns_present() become >> + * effective. If CONFIG_SPARSEMEM is not defined, pfns_present() >> + * always returns 0. >> + */ >> + ret = pfns_present(pfn, nr_pages); >> + if (ret) { >> + unlock_memory_hotplug(); >> + return ret; >> + } >> arg.start_pfn = pfn; >> arg.nr_pages = nr_pages; >> arg.status_change_nid = -1; >
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