The patch titled
Subject: mm: fix free page check in zone_watermark_ok()
has been removed from the -mm tree. Its filename was
mm-bug-fix-free-page-check-in-zone_watermark_ok.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm: fix free page check in zone_watermark_ok()
__zone_watermark_ok currently compares free_pages which is a signed type
with z->lowmem_reserve[classzone_idx] which is unsigned which might lead
to sign overflow if free_pages doesn't satisfy the given order (or it came
as negative already) and then we rely on the following order loop to fix
it (which doesn't work for order-0). Let's fix the type conversion and do
not rely on the given value of free_pages or follow up fixups.
This patch fixes it because "memory-hotplug: fix kswapd looping forever
problem" depends on this.
As benefit of this patch, it doesn't rely on the loop to exit
__zone_watermark_ok in case of high order check and make the first test
effective.(ie, if (free_pages <= min + lowmem_reserve))
Aaditya reported this problem when he test my hotplug patch.
Reported-off-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>
Tested-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>
Signed-off-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-bug-fix-free-page-check-in-zone_watermark_ok mm/page_alloc.c
--- a/mm/page_alloc.c~mm-bug-fix-free-page-check-in-zone_watermark_ok
+++ a/mm/page_alloc.c
@@ -1595,6 +1595,7 @@ static bool __zone_watermark_ok(struct z
{
/* free_pages my go negative - that's OK */
long min = mark;
+ long lowmem_reserve = z->lowmem_reserve[classzone_idx];
int o;
free_pages -= (1 << order) - 1;
@@ -1603,7 +1604,7 @@ static bool __zone_watermark_ok(struct z
if (alloc_flags & ALLOC_HARDER)
min -= min / 4;
- if (free_pages <= min + z->lowmem_reserve[classzone_idx])
+ if (free_pages <= min + lowmem_reserve)
return false;
for (o = 0; o < order; o++) {
/* At the next order, this order's pages become unavailable */
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
origin.patch
mm-remove-__gfp_no_kswapd.patch
remove-__gfp_no_kswapd-fixes-fix.patch
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