"Rafael J. Wysocki" <[email protected]> wrote:
>
> Make shrink_all_memory() overflow-resistant.
>
As you've probably noticed, I'm moving toward making all the scalars which
hold counts of pages in the VM toward unsigned long. For uniformity, and
because there is a small risk that a huge machine with 4k pages could
actually overflow a 32-bit counter.
> Signed-off-by: Rafael J. Wysocki <[email protected]>
> ---
> include/linux/swap.h | 2 +-
> mm/vmscan.c | 9 +++++----
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> Index: linux-2.6.16-rc4-mm2/mm/vmscan.c
> ===================================================================
> --- linux-2.6.16-rc4-mm2.orig/mm/vmscan.c
> +++ linux-2.6.16-rc4-mm2/mm/vmscan.c
> @@ -1785,18 +1785,19 @@ void wakeup_kswapd(struct zone *zone, in
> * Try to free `nr_pages' of memory, system-wide. Returns the number of freed
> * pages.
> */
> -int shrink_all_memory(unsigned long nr_pages)
> +unsigned long shrink_all_memory(unsigned int nr_pages)
So nr_pages should remain unsigned long.
> + long long nr_to_free = nr_pages;
As should nr_to_free.
The actual bug is the (unsigned <= 0) thing. So how's about this?
--- devel/include/linux/swap.h~vmscan-use-unsigned-longs-shrink_all_memory-fix 2006-02-27 19:13:30.000000000 -0800
+++ devel-akpm/include/linux/swap.h 2006-02-27 19:13:30.000000000 -0800
@@ -173,7 +173,7 @@ extern void swap_setup(void);
/* linux/mm/vmscan.c */
extern unsigned long try_to_free_pages(struct zone **, gfp_t);
-extern int shrink_all_memory(unsigned long nr_pages);
+extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
#ifdef CONFIG_NUMA
--- devel/mm/vmscan.c~vmscan-use-unsigned-longs-shrink_all_memory-fix 2006-02-27 19:13:30.000000000 -0800
+++ devel-akpm/mm/vmscan.c 2006-02-27 19:13:30.000000000 -0800
@@ -1779,22 +1779,23 @@ void wakeup_kswapd(struct zone *zone, in
* Try to free `nr_pages' of memory, system-wide. Returns the number of freed
* pages.
*/
-int shrink_all_memory(unsigned long nr_pages)
+unsigned long shrink_all_memory(unsigned long nr_pages)
{
pg_data_t *pgdat;
unsigned long nr_to_free = nr_pages;
- int ret = 0;
+ unsigned long ret = 0;
struct reclaim_state reclaim_state = {
.reclaimed_slab = 0,
};
current->reclaim_state = &reclaim_state;
for_each_pgdat(pgdat) {
- int freed;
+ unsigned long freed;
+
freed = balance_pgdat(pgdat, nr_to_free, 0);
ret += freed;
nr_to_free -= freed;
- if (nr_to_free <= 0)
+ if ((long)nr_to_free <= 0)
break;
}
current->reclaim_state = NULL;
_
-
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