linux-kernel - [RFC/PATCH] Use mmu_gather for /proc stuff instead of flush_tlb

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Message-Id: <1183963599.5961.7.camel@localhost.localdomain>
Date:	Mon, 09 Jul 2007 16:46:39 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	linux-mm@...ck.org
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: [RFC/PATCH] Use mmu_gather for /proc stuff instead of
	flush_tlb_mm()

Use mmu_gather for fs/proc/task_mmu.c

This removes the use of flush_tlb_mm() from that proc file, using
an mmu_gather instead.

No signed-off yet, not to be merged at this point.


Index: linux-work/fs/proc/task_mmu.c
===================================================================
--- linux-work.orig/fs/proc/task_mmu.c	2007-07-09 16:27:09.000000000 +1000
+++ linux-work/fs/proc/task_mmu.c	2007-07-09 16:27:47.000000000 +1000
@@ -9,7 +9,7 @@
 
 #include <asm/elf.h>
 #include <asm/uaccess.h>
-#include <asm/tlbflush.h>
+#include <asm/tlb.h>
 #include "internal.h"
 
 char *task_mem(struct mm_struct *mm, char *buffer)
@@ -124,11 +124,13 @@ struct mem_size_stats
 	unsigned long referenced;
 };
 
+typedef void (*pmd_action_t)(struct mmu_gather *tlb, struct vm_area_struct *,
+			     pmd_t *, unsigned long, unsigned long, void *);
 struct pmd_walker {
+	struct mmu_gather *tlb;
 	struct vm_area_struct *vma;
 	void *private;
-	void (*action)(struct vm_area_struct *, pmd_t *, unsigned long,
-		       unsigned long, void *);
+	pmd_action_t action;
 };
 
 static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats *mss)
@@ -218,7 +220,8 @@ static int show_map(struct seq_file *m, 
 	return show_map_internal(m, v, NULL);
 }
 
-static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+static void smaps_pte_range(struct mmu_gather *tlb,
+			    struct vm_area_struct *vma, pmd_t *pmd,
 			    unsigned long addr, unsigned long end,
 			    void *private)
 {
@@ -258,7 +261,8 @@ static void smaps_pte_range(struct vm_ar
 	cond_resched();
 }
 
-static void clear_refs_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+static void clear_refs_pte_range(struct mmu_gather *tlb,
+				 struct vm_area_struct *vma, pmd_t *pmd,
 				 unsigned long addr, unsigned long end,
 				 void *private)
 {
@@ -279,6 +283,8 @@ static void clear_refs_pte_range(struct 
 		/* Clear accessed and referenced bits. */
 		ptep_test_and_clear_young(vma, addr, pte);
 		ClearPageReferenced(page);
+		if (tlb)
+			tlb_remove_tlb_entry(tlb, pte, addr);
 	}
 	pte_unmap_unlock(pte - 1, ptl);
 	cond_resched();
@@ -295,7 +301,8 @@ static inline void walk_pmd_range(struct
 		next = pmd_addr_end(addr, end);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		walker->action(walker->vma, pmd, addr, next, walker->private);
+		walker->action(walker->tlb, walker->vma, pmd, addr, next,
+			       walker->private);
 	}
 }
 
@@ -323,11 +330,9 @@ static inline void walk_pud_range(struct
  * Recursively walk the page table for the memory area in a VMA, calling
  * a callback for every bottom-level (PTE) page table.
  */
-static inline void walk_page_range(struct vm_area_struct *vma,
-				   void (*action)(struct vm_area_struct *,
-						  pmd_t *, unsigned long,
-						  unsigned long, void *),
-				   void *private)
+static inline void walk_page_range(struct mmu_gather *tlb,
+				   struct vm_area_struct *vma,
+				   pmd_action_t	action, void *private)
 {
 	unsigned long addr = vma->vm_start;
 	unsigned long end = vma->vm_end;
@@ -335,6 +340,7 @@ static inline void walk_page_range(struc
 		.vma		= vma,
 		.private	= private,
 		.action		= action,
+		.tlb		= tlb,
 	};
 	pgd_t *pgd;
 	unsigned long next;
@@ -355,19 +361,25 @@ static int show_smap(struct seq_file *m,
 
 	memset(&mss, 0, sizeof mss);
 	if (vma->vm_mm && !is_vm_hugetlb_page(vma))
-		walk_page_range(vma, smaps_pte_range, &mss);
+		walk_page_range(NULL, vma, smaps_pte_range, &mss);
 	return show_map_internal(m, v, &mss);
 }
 
 void clear_refs_smap(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
+	struct mmu_gather *tlb;
+	unsigned long end_addr = 0;
 
 	down_read(&mm->mmap_sem);
+	tlb = tlb_gather_mmu(mm, 0);
 	for (vma = mm->mmap; vma; vma = vma->vm_next)
-		if (vma->vm_mm && !is_vm_hugetlb_page(vma))
-			walk_page_range(vma, clear_refs_pte_range, NULL);
-	flush_tlb_mm(mm);
+		if (vma->vm_mm && !is_vm_hugetlb_page(vma)) {
+			end_addr = max(vma->vm_end, end_addr);
+			walk_page_range(tlb, vma, clear_refs_pte_range, NULL);
+		}
+	if (tlb)
+		tlb_finish_mmu(tlb, 0, end_addr);
 	up_read(&mm->mmap_sem);
 }
 


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