[PATCH] mm->rss is modified without page_table_lock held

[Rasmus Andersen <rasmus@jaquet.dk>]

Hi.

The following patch moves the page_table_lock in mm/* to cover the
modification of mm->rss in 240-test12-pre7. It was inspired by a 
similar patch from davej(?) which covered too much, AFAIR. The item 
is on Tytso's ToDo list.

Please comment.


diff -Naur linux-240-t12-pre7-clean/mm/memory.c linux/mm/memory.c
--- linux-240-t12-pre7-clean/mm/memory.c	Fri Dec  8 00:45:04 2000
+++ linux/mm/memory.c	Fri Dec  8 00:48:26 2000
@@ -371,7 +371,6 @@
 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (address && (address < end));
-	spin_unlock(&mm->page_table_lock);
 	/*
 	 * Update rss for the mm_struct (not necessarily current->mm)
 	 * Notice that rss is an unsigned long.
@@ -380,6 +379,7 @@
 		mm->rss -= freed;
 	else
 		mm->rss = 0;
+	spin_unlock(&mm->page_table_lock);
 }
 
 
@@ -1076,7 +1076,9 @@
 		flush_icache_page(vma, page);
 	}
 
+	spin_lock(&mm->page_table_lock);
 	mm->rss++;
+	spin_unlock(&mm->page_table_lock);
 
 	pte = mk_pte(page, vma->vm_page_prot);
 
@@ -1110,7 +1112,9 @@
 			return -1;
 		clear_user_highpage(page, addr);
 		entry = pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
+		spin_lock(&mm->page_table_lock);
 		mm->rss++;
+		spin_unlock(&mm->page_table_lock);
 		flush_page_to_ram(page);
 	}
 	set_pte(page_table, entry);
@@ -1149,7 +1153,9 @@
 		return 0;
 	if (new_page == NOPAGE_OOM)
 		return -1;
+	spin_lock(&mm->page_table_lock);
 	++mm->rss;
+	spin_unlock(&mm->page_table_lock);
 	/*
 	 * This silly early PAGE_DIRTY setting removes a race
 	 * due to the bad i386 page protection. But it's valid
diff -Naur linux-240-t12-pre7-clean/mm/mmap.c linux/mm/mmap.c
--- linux-240-t12-pre7-clean/mm/mmap.c	Wed Nov 22 22:41:45 2000
+++ linux/mm/mmap.c	Fri Dec  8 00:48:26 2000
@@ -889,8 +889,8 @@
 	spin_lock(&mm->page_table_lock);
 	mpnt = mm->mmap;
 	mm->mmap = mm->mmap_avl = mm->mmap_cache = NULL;
-	spin_unlock(&mm->page_table_lock);
 	mm->rss = 0;
+	spin_unlock(&mm->page_table_lock);
 	mm->total_vm = 0;
 	mm->locked_vm = 0;
 	while (mpnt) {
diff -Naur linux-240-t12-pre7-clean/mm/swapfile.c linux/mm/swapfile.c
--- linux-240-t12-pre7-clean/mm/swapfile.c	Sat Nov  4 23:27:17 2000
+++ linux/mm/swapfile.c	Fri Dec  8 00:48:26 2000
@@ -231,7 +231,9 @@
 	set_pte(dir, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 	swap_free(entry);
 	get_page(page);
+	spin_lock(&vma->vm_mm->page_table_lock);
 	++vma->vm_mm->rss;
+	spin_unlock(&vma->vm_mm->page_table_lock);
 }
 
 static inline void unuse_pmd(struct vm_area_struct * vma, pmd_t *dir,
diff -Naur linux-240-t12-pre7-clean/mm/vmscan.c linux/mm/vmscan.c
--- linux-240-t12-pre7-clean/mm/vmscan.c	Fri Dec  8 00:45:04 2000
+++ linux/mm/vmscan.c	Fri Dec  8 00:48:26 2000
@@ -98,7 +98,9 @@
 		set_pte(page_table, swp_entry_to_pte(entry));
 drop_pte:
 		UnlockPage(page);
+		spin_lock(&mm->page_table_lock);
 		mm->rss--;
+		spin_unlock(&mm->page_table_lock);
 		flush_tlb_page(vma, address);
 		deactivate_page(page);
 		page_cache_release(page);

-- 
Regards,
        Rasmus(rasmus@jaquet.dk)

You know how dumb the average guy is?  Well, by  definition, half
of them are even dumber than that.
            -- J.R. "Bob" Dobbs 
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