On Mon, Jun 26, 2017 at 11:59:52PM -0700, John Hubbard wrote: >On 06/26/2017 04:40 PM, Wei Yang wrote: >> On Mon, Jun 26, 2017 at 12:32:40AM -0700, John Hubbard wrote: >>> On 06/24/2017 07:52 PM, Wei Yang wrote: >[...] >>> >>> Why is it safe to assume no holes in the memory range? (Maybe Michal's >>> patch already covered this and I haven't got that far yet?) >>> >>> The documentation for this routine says that it walks through all >>> present memory sections in the range, so it seems like this patch >>> breaks that. >>> >> >> Hmm... it is a little bit hard to describe. >> >> First the documentation of the function is a little misleading. When you look >> at the code, it call the "func" only once for a memory_block, not for every >> present mem_section as it says. So have some memory in the memory_block would >> meet the requirement. >> >> Second, after the check in patch 1, it is for sure the range is memory_block >> aligned, which means it must have some memory in that memory_block. It would >> be strange if someone claim to add a memory range but with no real memory. >> >> This is why I remove the check here. > >OK. In that case, it seems like we should update the function documentation >to match. Something like this, maybe? : > >diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >index bdaafcf46f49..d36b2f4eaf39 100644 >--- a/mm/memory_hotplug.c >+++ b/mm/memory_hotplug.c >@@ -1872,14 +1872,14 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages) > #endif /* CONFIG_MEMORY_HOTREMOVE */ > > /** >- * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn) >+ * walk_memory_range - walks through all mem blocks in [start_pfn, end_pfn) > * @start_pfn: start pfn of the memory range > * @end_pfn: end pfn of the memory range > * @arg: argument passed to func >- * @func: callback for each memory section walked >+ * @func: callback for each memory block walked > * >- * This function walks through all present mem sections in range >- * [start_pfn, end_pfn) and call func on each mem section. >+ * This function walks through all mem blocks in the range >+ * [start_pfn, end_pfn) and calls func on each mem block. > * > * Returns the return value of func. > */ > Yes, I have changed this in my repo. > >thanks, >john h -- Wei Yang Help you, Help me
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