Re: [PATCHv4 02/10] mm: convert mm->nr_ptes to atomic_t
From: Cody P Schafer
Date: Fri Sep 27 2013 - 16:47:09 EST
On 09/27/2013 06:16 AM, Kirill A. Shutemov wrote:
With split page table lock for PMD level we can't hold
mm->page_table_lock while updating nr_ptes.
Let's convert it to atomic_t to avoid races.
---
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 84e0c56e1e..99f19e850d 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -339,6 +339,7 @@ struct mm_struct {
pgd_t * pgd;
atomic_t mm_users; /* How many users with user space? */
atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
+ atomic_t nr_ptes; /* Page table pages */
int map_count; /* number of VMAs */
spinlock_t page_table_lock; /* Protects page tables and some counters */
@@ -360,7 +361,6 @@ struct mm_struct {
unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE */
unsigned long stack_vm; /* VM_GROWSUP/DOWN */
unsigned long def_flags;
- unsigned long nr_ptes; /* Page table pages */
unsigned long start_code, end_code, start_data, end_data;
unsigned long start_brk, brk, start_stack;
unsigned long arg_start, arg_end, env_start, env_end;
Will 32bits always be enough here? Should atomic_long_t be used instead?
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