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Commit 7de6b805 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

[PATCH] mm: more rmap debugging 



Add more debugging in the rmap code in an attempt to locate to source of
the occasional "mapcount went negative" assertions.

Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 19900cde

include/linux/rmap.h

+1 −1
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ void __anon_vma_link(struct vm_area_struct *); 
void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);

void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);

void page_add_file_rmap(struct page *);

void page_remove_rmap(struct page *);

void page_remove_rmap(struct page *, struct vm_area_struct *);



/**

 * page_dup_rmap - duplicate pte mapping to a page

mm/filemap_xip.c

+1 −1
Original line number Diff line number Diff line
@@ -189,7 +189,7 @@ __xip_unmap (struct address_space * mapping, 
			/* Nuke the page table entry. */

			flush_cache_page(vma, address, pte_pfn(*pte));

			pteval = ptep_clear_flush(vma, address, pte);

			page_remove_rmap(page);

			page_remove_rmap(page, vma);

			dec_mm_counter(mm, file_rss);

			BUG_ON(pte_dirty(pteval));

			pte_unmap_unlock(pte, ptl);

mm/fremap.c

+1 −1
Original line number Diff line number Diff line
@@ -33,7 +33,7 @@ static int zap_pte(struct mm_struct *mm, struct vm_area_struct *vma, 
		if (page) {

			if (pte_dirty(pte))

				set_page_dirty(page);

			page_remove_rmap(page);

			page_remove_rmap(page, vma);

			page_cache_release(page);

		}

	} else {

mm/memory.c

+2 −2
Original line number Diff line number Diff line
@@ -681,7 +681,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, 
					mark_page_accessed(page);

				file_rss--;

			}

			page_remove_rmap(page);

			page_remove_rmap(page, vma);

			tlb_remove_page(tlb, page);

			continue;

		}
@@ -1586,7 +1586,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);

	if (likely(pte_same(*page_table, orig_pte))) {

		if (old_page) {

			page_remove_rmap(old_page);

			page_remove_rmap(old_page, vma);

			if (!PageAnon(old_page)) {

				dec_mm_counter(mm, file_rss);

				inc_mm_counter(mm, anon_rss);

mm/rmap.c

+10 −3
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ 
#include <linux/rmap.h>

#include <linux/rcupdate.h>

#include <linux/module.h>

#include <linux/kallsyms.h>



#include <asm/tlbflush.h>
@@ -567,14 +568,20 @@ void page_add_file_rmap(struct page *page) 
 *

 * The caller needs to hold the pte lock.

 */

void page_remove_rmap(struct page *page)

void page_remove_rmap(struct page *page, struct vm_area_struct *vma)

{

	if (atomic_add_negative(-1, &page->_mapcount)) {

		if (unlikely(page_mapcount(page) < 0)) {

			printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));

			printk (KERN_EMERG "  page pfn = %lx\n", page_to_pfn(page));

			printk (KERN_EMERG "  page->flags = %lx\n", page->flags);

			printk (KERN_EMERG "  page->count = %x\n", page_count(page));

			printk (KERN_EMERG "  page->mapping = %p\n", page->mapping);

			print_symbol (KERN_EMERG "  vma->vm_ops = %s\n", (unsigned long)vma->vm_ops);

			if (vma->vm_ops)

				print_symbol (KERN_EMERG "  vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage);

			if (vma->vm_file && vma->vm_file->f_op)

				print_symbol (KERN_EMERG "  vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap);

			BUG();

		}
@@ -679,7 +686,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, 
		dec_mm_counter(mm, file_rss);





	page_remove_rmap(page);

	page_remove_rmap(page, vma);

	page_cache_release(page);



out_unmap:
@@ -769,7 +776,7 @@ static void try_to_unmap_cluster(unsigned long cursor, 
		if (pte_dirty(pteval))

			set_page_dirty(page);



		page_remove_rmap(page);

		page_remove_rmap(page, vma);

		page_cache_release(page);

		dec_mm_counter(mm, file_rss);

		(*mapcount)--;