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

From: Rasmus Andersen (rasmus@jaquet.dk)
Date: Fri Dec 08 2000 - 15:29:10 EST

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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This archive was generated by hypermail 2b29 : Fri Dec 15 2000 - 21:00:15 EST