[PATCH] report per-process pagetable usage

Andi Kleen requested that the number of pagetable pages in use by a process
be reported in /proc/$PID/status; this patch implements that.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/mm/hugetlbpage.c

@@ -247,6 +247,7 @@ int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
 
 			page = pmd_page(*pmd);
 			pmd_clear(pmd);
+			mm->nr_ptes--;
 			dec_page_state(nr_page_table_pages);
 			page_cache_release(page);
 		}

arch/ppc64/mm/hugetlbpage.c

@@ -213,6 +213,7 @@ static int prepare_low_seg_for_htlb(struct mm_struct *mm, unsigned long seg)
 		}
 		page = pmd_page(*pmd);
 		pmd_clear(pmd);
+		mm->nr_ptes--;
 		dec_page_state(nr_page_table_pages);
 		pte_free_tlb(tlb, page);
 	}

fs/proc/task_mmu.c

@@ -18,12 +18,14 @@ char *task_mem(struct mm_struct *mm, char *buffer)
 		"VmData:\t%8lu kB\n"
 		"VmStk:\t%8lu kB\n"
 		"VmExe:\t%8lu kB\n"
-		"VmLib:\t%8lu kB\n",
+		"VmLib:\t%8lu kB\n"
+		"VmPTE:\t%8lu kB\n",
 		(mm->total_vm - mm->reserved_vm) << (PAGE_SHIFT-10),
 		mm->locked_vm << (PAGE_SHIFT-10),
 		mm->rss << (PAGE_SHIFT-10),
 		data << (PAGE_SHIFT-10),
-		mm->stack_vm << (PAGE_SHIFT-10), text, lib);
+		mm->stack_vm << (PAGE_SHIFT-10), text, lib,
+		(PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10);
 	return buffer;
 }
 

include/linux/sched.h

@@ -227,7 +227,7 @@ struct mm_struct {
 	unsigned long start_brk, brk, start_stack;
 	unsigned long arg_start, arg_end, env_start, env_end;
 	unsigned long rss, total_vm, locked_vm, shared_vm;
-	unsigned long exec_vm, stack_vm, reserved_vm, def_flags;
+	unsigned long exec_vm, stack_vm, reserved_vm, def_flags, nr_ptes;
 
 	unsigned long saved_auxv[42]; /* for /proc/PID/auxv */
 

kernel/fork.c

@@ -302,6 +302,7 @@ static struct mm_struct * mm_init(struct mm_struct * mm)
 	atomic_set(&mm->mm_count, 1);
 	init_rwsem(&mm->mmap_sem);
 	mm->core_waiters = 0;
+	mm->nr_ptes = 0;
 	mm->page_table_lock = SPIN_LOCK_UNLOCKED;
 	mm->ioctx_list_lock = RW_LOCK_UNLOCKED;
 	mm->ioctx_list = NULL;

mm/memory.c

@@ -114,6 +114,7 @@ static inline void free_one_pmd(struct mmu_gather *tlb, pmd_t * dir)
 	page = pmd_page(*dir);
 	pmd_clear(dir);
 	dec_page_state(nr_page_table_pages);
+	tlb->mm->nr_ptes--;
 	pte_free_tlb(tlb, page);
 }
 
@@ -163,7 +164,6 @@ pte_t fastcall * pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long a
 		spin_lock(&mm->page_table_lock);
 		if (!new)
 			return NULL;
-
 		/*
 		 * Because we dropped the lock, we should re-check the
 		 * entry, as somebody else could have populated it..
@@ -172,6 +172,7 @@ pte_t fastcall * pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long a
 			pte_free(new);
 			goto out;
 		}
+		mm->nr_ptes++;
 		inc_page_state(nr_page_table_pages);
 		pmd_populate(mm, pmd, new);
 	}