[lc-checkins] CVS: linux/mm/comp_cache free.c,1.41,1.42 vswap.c,1.42,1.43

[Rodrigo S. de C. <rc...@us...>]

Update of /cvsroot/linuxcompressed/linux/mm/comp_cache
In directory usw-pr-cvs1:/tmp/cvs-serv19795/mm/comp_cache

Modified Files:
	free.c vswap.c 
Log Message:
Bug fixes
o Fixed race between comp_cache_use_address() and do_swap_page(). A pte
could be unsafely changed during a page fault service.



Index: free.c
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/mm/comp_cache/free.c,v
retrieving revision 1.41
retrieving revision 1.42
diff -C2 -r1.41 -r1.42
*** free.c	18 Jul 2002 11:54:48 -0000	1.41
--- free.c	18 Jul 2002 13:32:50 -0000	1.42
***************
*** 2,6 ****
   * linux/mm/comp_cache/free.c
   *
!  * Time-stamp: <2002-07-18 08:40:22 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
--- 2,6 ----
   * linux/mm/comp_cache/free.c
   *
!  * Time-stamp: <2002-07-18 10:04:09 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
***************
*** 279,282 ****
--- 279,285 ----
  		old_entry = SWP_ENTRY(COMP_CACHE_SWP_TYPE, vswap->offset);
  
+ 		if (vswap->fault_count)
+ 			continue;
+ 
  		if (TryLockPage(vswap->fragment->comp_page->page))
  			continue;
***************
*** 301,307 ****
  
  	/* set old virtual addressed ptes to the real swap entry */
  	ret = set_pte_list_to_entry(vswap->pte_list, old_entry, entry);
  
! 	if (!ret)
  		goto backout;
  
--- 304,315 ----
  
  	/* set old virtual addressed ptes to the real swap entry */
+ 	spin_unlock(&virtual_swap_list);
  	ret = set_pte_list_to_entry(vswap->pte_list, old_entry, entry);
+ 	spin_lock(&virtual_swap_list);
  
! 	/* if we set all the pte list, but while setting to the new
! 	 * entry, a pte has faulted in, back out the changes so
! 	 * hopefully the page fault can be serviced */
! 	if (!ret || vswap->fault_count)
  		goto backout;
  
***************
*** 318,330 ****
  	}
  
- 	if (vswap->swap_cache_page) {
- 		if (vswap->swap_count != 1)		
- 			BUG();
- 	}
- 	else {
- 		if (vswap->swap_count)
- 			BUG();
- 	}
- 	
  	/* let's fix swap cache page address (if any) */
  	if (vswap->swap_cache_page) {
--- 326,329 ----
***************
*** 347,351 ****
  	}
  
! 	if (vswap->swap_count)
  		BUG();
  	
--- 346,354 ----
  	}
  
! 	/* Even if the swap cache page has been removed but the
! 	 * swap_count not yet decremented, the maximum value of
! 	 * swap_count is 1. This vswap entry will be added to free
! 	 * list as soon as swap_count gets to zero. */
! 	if (vswap->swap_count > 1)
  		BUG();
  	

Index: vswap.c
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/mm/comp_cache/vswap.c,v
retrieving revision 1.42
retrieving revision 1.43
diff -C2 -r1.42 -r1.43
*** vswap.c	17 Jul 2002 20:44:36 -0000	1.42
--- vswap.c	18 Jul 2002 13:32:51 -0000	1.43
***************
*** 2,6 ****
   * linux/mm/comp_cache/vswap.c
   *
!  * Time-stamp: <2002-07-17 16:48:47 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
--- 2,6 ----
   * linux/mm/comp_cache/vswap.c
   *
!  * Time-stamp: <2002-07-18 10:01:50 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
***************
*** 708,711 ****
--- 708,730 ----
  	spin_unlock(&virtual_swap_list);
  }
+ 
+ void FASTCALL(get_vswap(swp_entry_t));
+ void get_vswap(swp_entry_t entry) {
+ 	if (!vswap_address(entry))
+ 		return;
+ 	spin_lock(&virtual_swap_list);
+ 	vswap_address[SWP_OFFSET(entry)]->fault_count++;
+ 	spin_unlock(&virtual_swap_list);
+ }
+ 
+ void FASTCALL(put_vswap(swp_entry_t));
+ void put_vswap(swp_entry_t entry) {
+ 	if (!vswap_address(entry))
+ 		return;
+ 	spin_lock(&virtual_swap_list);
+ 	vswap_address[SWP_OFFSET(entry)]->fault_count--;
+ 	spin_unlock(&virtual_swap_list);
+ }
+ 
  
  /**