This needed highmem fix from Rik is still missing too, so please apply
along the other 5 (it's orthogonal so you can apply this one in any
order you want).
From: Rik van Riel <[EMAIL PROTECTED]>
Subject: [PATCH][1/2] adjust dirty threshold for lowmem-only mappings
Simply running "dd if=/dev/zero of=/dev/hd<one you can miss>" will
result in OOM kills, with the dirty pagecache completely filling up
lowmem. This patch is part 1 to fixing that problem.
This patch effectively lowers the dirty limit for mappings which cannot
be cached in highmem, counting the dirty limit as a percentage of lowmem
instead. This should prevent heavy block device writers from pushing
the VM over the edge and triggering OOM kills.
Signed-off-by: Rik van Riel <[EMAIL PROTECTED]>
Acked-by: Andrea Arcangeli <[EMAIL PROTECTED]>
--- x/mm/page-writeback.c.orig 2005-01-04 01:13:30.000000000 +0100
+++ x/mm/page-writeback.c 2005-01-04 02:41:29.573177184 +0100
@@ -133,7 +133,8 @@ static void get_writeback_state(struct w
* clamping level.
*/
static void
-get_dirty_limits(struct writeback_state *wbs, long *pbackground, long *pdirty)
+get_dirty_limits(struct writeback_state *wbs, long *pbackground, long *pdirty,
+ struct address_space *mapping)
{
int background_ratio; /* Percentages */
int dirty_ratio;
@@ -141,10 +142,20 @@ get_dirty_limits(struct writeback_state
long background;
long dirty;
struct task_struct *tsk;
+ unsigned long available_memory = total_pages;
get_writeback_state(wbs);
- unmapped_ratio = 100 - (wbs->nr_mapped * 100) / total_pages;
+#ifdef CONFIG_HIGHMEM
+ /*
+ * In some cases we can only allocate from low memory,
+ * so we exclude high memory from our count.
+ */
+ if (mapping && !(mapping_gfp_mask(mapping) & __GFP_HIGHMEM))
+ available_memory -= totalhigh_pages;
+#endif
+
+ unmapped_ratio = 100 - (wbs->nr_mapped * 100) / available_memory;
dirty_ratio = vm_dirty_ratio;
if (dirty_ratio > unmapped_ratio / 2)
@@ -194,7 +205,7 @@ static void balance_dirty_pages(struct a
.nr_to_write = write_chunk,
};
- get_dirty_limits(&wbs, &background_thresh, &dirty_thresh);
+ get_dirty_limits(&wbs, &background_thresh, &dirty_thresh,
mapping);
nr_reclaimable = wbs.nr_dirty + wbs.nr_unstable;
if (nr_reclaimable + wbs.nr_writeback <= dirty_thresh)
break;
@@ -210,7 +221,7 @@ static void balance_dirty_pages(struct a
if (nr_reclaimable) {
writeback_inodes(&wbc);
get_dirty_limits(&wbs, &background_thresh,
- &dirty_thresh);
+ &dirty_thresh, mapping);
nr_reclaimable = wbs.nr_dirty + wbs.nr_unstable;
if (nr_reclaimable + wbs.nr_writeback <= dirty_thresh)
break;
@@ -296,7 +307,7 @@ static void background_writeout(unsigned
long background_thresh;
long dirty_thresh;
- get_dirty_limits(&wbs, &background_thresh, &dirty_thresh);
+ get_dirty_limits(&wbs, &background_thresh, &dirty_thresh, NULL);
if (wbs.nr_dirty + wbs.nr_unstable < background_thresh
&& min_pages <= 0)
break;
-
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