[PATCH] sched, numa, mm: Add memcg support to do_huge_pmd_numa_page()

[Ingo Molnar]

* Zhouping Liu <zliu@xxxxxxxxxx> wrote:

> Hi Johannes,
> 
> Tested the below patch, and I'm sure it has fixed the above 
> issue, thank you.

Thanks. Below is the folded up patch.

	Ingo

---------------------------->
Subject: sched, numa, mm: Add memcg support to do_huge_pmd_numa_page()
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Date: Thu Oct 25 12:49:51 CEST 2012

Add memory control group support to hugepage migration.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Tested-by: Zhouping Liu <zliu@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-rDk9mgpoyhZlwh2xhlykvgnp@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 mm/huge_memory.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

Index: tip/mm/huge_memory.c
===================================================================
--- tip.orig/mm/huge_memory.c
+++ tip/mm/huge_memory.c
@@ -743,6 +743,7 @@ void do_huge_pmd_numa_page(struct mm_str
 			   unsigned int flags, pmd_t entry)
 {
 	unsigned long haddr = address & HPAGE_PMD_MASK;
+	struct mem_cgroup *memcg = NULL;
 	struct page *new_page = NULL;
 	struct page *page = NULL;
 	int node, lru;
@@ -833,6 +834,14 @@ migrate:
 
 		return;
 	}
+	/*
+	 * Traditional migration needs to prepare the memcg charge
+	 * transaction early to prevent the old page from being
+	 * uncharged when installing migration entries.  Here we can
+	 * save the potential rollback and start the charge transfer
+	 * only when migration is already known to end successfully.
+	 */
+	mem_cgroup_prepare_migration(page, new_page, &memcg);
 
 	entry = mk_pmd(new_page, vma->vm_page_prot);
 	entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
@@ -843,6 +852,12 @@ migrate:
 	set_pmd_at(mm, haddr, pmd, entry);
 	update_mmu_cache_pmd(vma, address, entry);
 	page_remove_rmap(page);
+	/*
+	 * Finish the charge transaction under the page table lock to
+	 * prevent split_huge_page() from dividing up the charge
+	 * before it's fully transferred to the new page.
+	 */
+	mem_cgroup_end_migration(memcg, page, new_page, true);
 	spin_unlock(&mm->page_table_lock);
 
 	put_page(page);			/* Drop the rmap reference */

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