mm: check nr_initialised with PAGES_PER_SECTION directly in defer_init() (23b68cfa) · Commits · 戴 / test

When DEFERRED_STRUCT_PAGE_INIT is configured, only the first section of each node's highest zone is initialized before defer stage. static_init_pgcnt is used to store the number of pages like this: pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION, pgdat->node_spanned_pages); because we don't want to overflow zone's range. But this is not necessary, since defer_init() is called like this: memmap_init_zone() for pfn in [start_pfn, end_pfn) defer_init(pfn, end_pfn) In case (pgdat->node_spanned_pages < PAGES_PER_SECTION), the loop would stop before calling defer_init(). BTW, comparing PAGES_PER_SECTION with node_spanned_pages is not correct, since nr_initialised is zone based instead of node based. Even node_spanned_pages is bigger than PAGES_PER_SECTION, its highest zone would have pages less than PAGES_PER_SECTION. Link: http://lkml.kernel.org/r/20181122094807.6985-1-richard.weiyang@gmail.com Signed-off-by:

Wei Yang <richard.weiyang@gmail.com> Reviewed-by:

Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mmzone.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -692,8 +692,6 @@ typedef struct pglist_data {
		* is the first PFN that needs to be initialised.
		*/
		unsigned long first_deferred_pfn;
		/* Number of non-deferred pages */
		unsigned long static_init_pgcnt;
		#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

		#ifdef CONFIG_TRANSPARENT_HUGEPAGE

mm/page_alloc.c

+6 −7

Original line number	Diff line number	Diff line
		@@ -326,8 +326,13 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
		/* Always populate low zones for address-constrained allocations */
		if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
		return false;

		/*
		* We start only with one section of pages, more pages are added as
		* needed until the rest of deferred pages are initialized.
		*/
		nr_initialised++;
		if ((nr_initialised > NODE_DATA(nid)->static_init_pgcnt) &&
		if ((nr_initialised > PAGES_PER_SECTION) &&
		(pfn & (PAGES_PER_SECTION - 1)) == 0) {
		NODE_DATA(nid)->first_deferred_pfn = pfn;
		return true;
		@@ -6585,12 +6590,6 @@ static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
		#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
		static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
		{
		/*
		* We start only with one section of pages, more pages are added as
		* needed until the rest of deferred pages are initialized.
		*/
		pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
		pgdat->node_spanned_pages);
		pgdat->first_deferred_pfn = ULONG_MAX;
		}
		#else

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