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Commit 4daae3b4 authored by Mel Gorman's avatar Mel Gorman
Browse files

mm: mempolicy: Use _PAGE_NUMA to migrate pages 



Note: Based on "mm/mpol: Use special PROT_NONE to migrate pages" but
	sufficiently different that the signed-off-bys were dropped

Combine our previous _PAGE_NUMA, mpol_misplaced and migrate_misplaced_page()
pieces into an effective migrate on fault scheme.

Note that (on x86) we rely on PROT_NONE pages being !present and avoid
the TLB flush from try_to_unmap(TTU_MIGRATION). This greatly improves the
page-migration performance.

Based-on-work-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
parent 149c33e1

include/linux/huge_mm.h

+5 −4
Original line number Diff line number Diff line
@@ -160,8 +160,8 @@ static inline struct page *compound_trans_head(struct page *page) 
	return page;

}



extern int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,

				  pmd_t pmd, pmd_t *pmdp);

extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,

				unsigned long addr, pmd_t pmd, pmd_t *pmdp);



#else /* CONFIG_TRANSPARENT_HUGEPAGE */

#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
@@ -200,9 +200,10 @@ static inline int pmd_trans_huge_lock(pmd_t *pmd, 
	return 0;

}



static inline int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,

					pmd_t pmd, pmd_t *pmdp)

static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,

					unsigned long addr, pmd_t pmd, pmd_t *pmdp)

{

	return 0;

}



#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

mm/huge_memory.c

+28 −3
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/freezer.h>

#include <linux/mman.h>

#include <linux/pagemap.h>

#include <linux/migrate.h>

#include <asm/tlb.h>

#include <asm/pgalloc.h>

#include "internal.h"
@@ -1019,17 +1020,39 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 
}



/* NUMA hinting page fault entry point for trans huge pmds */

int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,

				pmd_t pmd, pmd_t *pmdp)

int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,

				unsigned long addr, pmd_t pmd, pmd_t *pmdp)

{

	struct page *page;

	struct page *page = NULL;

	unsigned long haddr = addr & HPAGE_PMD_MASK;

	int target_nid;



	spin_lock(&mm->page_table_lock);

	if (unlikely(!pmd_same(pmd, *pmdp)))

		goto out_unlock;



	page = pmd_page(pmd);

	get_page(page);

	spin_unlock(&mm->page_table_lock);



	target_nid = mpol_misplaced(page, vma, haddr);

	if (target_nid == -1)

		goto clear_pmdnuma;



	/*

	 * Due to lacking code to migrate thp pages, we'll split

	 * (which preserves the special PROT_NONE) and re-take the

	 * fault on the normal pages.

	 */

	split_huge_page(page);

	put_page(page);

	return 0;



clear_pmdnuma:

	spin_lock(&mm->page_table_lock);

	if (unlikely(!pmd_same(pmd, *pmdp)))

		goto out_unlock;



	pmd = pmd_mknonnuma(pmd);

	set_pmd_at(mm, haddr, pmdp, pmd);

	VM_BUG_ON(pmd_numa(*pmdp));
@@ -1037,6 +1060,8 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr, 


out_unlock:

	spin_unlock(&mm->page_table_lock);

	if (page)

		put_page(page);

	return 0;

}

mm/memory.c

+27 −5
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ 
#include <linux/swapops.h>

#include <linux/elf.h>

#include <linux/gfp.h>

#include <linux/migrate.h>



#include <asm/io.h>

#include <asm/pgalloc.h>
@@ -3451,8 +3452,9 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,

		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)

{

	struct page *page;

	struct page *page = NULL;

	spinlock_t *ptl;

	int current_nid, target_nid;



	/*

	* The "pte" at this point cannot be used safely without
@@ -3465,8 +3467,11 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	*/

	ptl = pte_lockptr(mm, pmd);

	spin_lock(ptl);

	if (unlikely(!pte_same(*ptep, pte)))

		goto out_unlock;

	if (unlikely(!pte_same(*ptep, pte))) {

		pte_unmap_unlock(ptep, ptl);

		goto out;

	}



	pte = pte_mknonnuma(pte);

	set_pte_at(mm, addr, ptep, pte);

	update_mmu_cache(vma, addr, ptep);
@@ -3477,8 +3482,25 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 
		return 0;

	}



out_unlock:

	get_page(page);

	current_nid = page_to_nid(page);

	target_nid = mpol_misplaced(page, vma, addr);

	pte_unmap_unlock(ptep, ptl);

	if (target_nid == -1) {

		/*

		 * Account for the fault against the current node if it not

		 * being replaced regardless of where the page is located.

		 */

		current_nid = numa_node_id();

		put_page(page);

		goto out;

	}



	/* Migrate to the requested node */

	if (migrate_misplaced_page(page, target_nid))

		current_nid = target_nid;



out:

	return 0;

}
@@ -3655,7 +3677,7 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
		barrier();

		if (pmd_trans_huge(orig_pmd)) {

			if (pmd_numa(*pmd))

				return do_huge_pmd_numa_page(mm, address,

				return do_huge_pmd_numa_page(mm, vma, address,

							     orig_pmd, pmd);



			if ((flags & FAULT_FLAG_WRITE) && !pmd_write(orig_pmd)) {