Commit 0247f3f4 authored Oct 07, 2016 by James Morse Committed by Linus Torvalds Oct 07, 2016

mm/memcontrol.c: make the walk_page_range() limit obvious

mem_cgroup_count_precharge() and mem_cgroup_move_charge() both call
walk_page_range() on the range 0 to ~0UL, neither provide a pte_hole
callback, which causes the current implementation to skip non-vma
regions.  This is all fine but follow up changes would like to make
walk_page_range more generic so it is better to be explicit about which
range to traverse so let's use highest_vm_end to explicitly traverse
only user mmaped memory.

[mhocko@kernel.org: rewrote changelog]
Link: http://lkml.kernel.org/r/1472655897-22532-1-git-send-email-james.morse@arm.com


Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 6fcb52a5

mm/memcontrol.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -4681,7 +4681,8 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
		.mm = mm,
		};
		down_read(&mm->mmap_sem);
		walk_page_range(0, ~0UL, &mem_cgroup_count_precharge_walk);
		walk_page_range(0, mm->highest_vm_end,
		&mem_cgroup_count_precharge_walk);
		up_read(&mm->mmap_sem);

		precharge = mc.precharge;
		@@ -4969,7 +4970,8 @@ retry:
		* When we have consumed all precharges and failed in doing
		* additional charge, the page walk just aborts.
		*/
		walk_page_range(0, ~0UL, &mem_cgroup_move_charge_walk);
		walk_page_range(0, mc.mm->highest_vm_end, &mem_cgroup_move_charge_walk);

		up_read(&mc.mm->mmap_sem);
		atomic_dec(&mc.from->moving_account);
		}

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