mm/memcontrol.c: cleanup some useless code (92855270) · Commits · 戴 / test

Compound pages handling in mem_cgroup_migrate is more convoluted than necessary. The state is duplicated in compound variable and the same could be achieved by PageTransHuge check which is trivial and hpage_nr_pages is already PageTransHuge aware. It is much simpler to just use hpage_nr_pages for nr_pages and replace the local variable by PageTransHuge check directly Link: http://lkml.kernel.org/r/20191210160450.3395-1-pilgrimtao@gmail.com Signed-off-by:

Kaitao Cheng <pilgrimtao@gmail.com> Acked-by:

Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by:

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

Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -6633,7 +6633,6 @@ void mem_cgroup_migrate(struct page oldpage, struct page newpage)
		{
		struct mem_cgroup *memcg;
		unsigned int nr_pages;
		bool compound;
		unsigned long flags;

		VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
		@@ -6655,8 +6654,7 @@ void mem_cgroup_migrate(struct page oldpage, struct page newpage)
		return;

		/* Force-charge the new page. The old one will be freed soon */
		compound = PageTransHuge(newpage);
		nr_pages = compound ? hpage_nr_pages(newpage) : 1;
		nr_pages = hpage_nr_pages(newpage);

		page_counter_charge(&memcg->memory, nr_pages);
		if (do_memsw_account())
		@@ -6666,7 +6664,8 @@ void mem_cgroup_migrate(struct page oldpage, struct page newpage)
		commit_charge(newpage, memcg, false);

		local_irq_save(flags);
		mem_cgroup_charge_statistics(memcg, newpage, compound, nr_pages);
		mem_cgroup_charge_statistics(memcg, newpage, PageTransHuge(newpage),
		nr_pages);
		memcg_check_events(memcg, newpage);
		local_irq_restore(flags);
		}

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