[PATCH] linux-2.1.91-pre2 crash fixed

[PATCH] linux-2.1.91-pre2 crash fixed

[Rik van Riel]

Hi Linus,

I've found a small typo in mm/filemap.c, which prevented
proper operation of the VM subsystem and, in effect, threw
kswapd in a loop.

In effect, it refused to free buffer memory when it was
_above_ the minimum percentage :)

Rik.
+-------------------------------------------+--------------------------+
| Linux: - LinuxHQ MM-patches page          | Scouting       webmaster |
|        - kswapd ask-him & complain-to guy | Vries    cubscout leader |
|     http://www.fys.ruu.nl/~riel/          | <H.H.vanRiel@fys.ruu.nl> |
+-------------------------------------------+--------------------------+

--- linux/mm/filemap.c.pre91-2	Thu Mar 26 15:03:44 1998
+++ linux/mm/filemap.c	Thu Mar 26 15:04:25 1998
@@ -152,7 +152,7 @@
 			} while (tmp != bh);
 
 			/* Refuse to swap out all buffer pages */
-			if ((buffermem >> PAGE_SHIFT) * 100 > (buffer_mem.min_percent * num_physpages))
+			if ((buffermem >> PAGE_SHIFT) * 100 < (buffer_mem.min_percent * num_physpages))
 				goto next;
 		}
 

Re: [PATCH] linux-2.1.91-pre2 crash fixed

[Dr. Werner Fink]

> I've found a small typo in mm/filemap.c, which prevented
> proper operation of the VM subsystem and, in effect, threw
> kswapd in a loop.
> 
> In effect, it refused to free buffer memory when it was
> _above_ the minimum percentage :)

This small type with its enormous effect I've mentioned a hour ago or so :)


BTW: Rik? I've a simple suggestion for the calculation of the number of
     free pages.  After the last kernel driver has done its allocation
     it would be usefull to remember the number of free pages with
     a global variable num_availpages and use this one instead of
     num_physpages for the most memory management operations.
     This would give a better protection for systems with less amount of
     physical ram to be out of the choosen limits for the VM subsystem.


              Werner