Watermarks are initialized during the postcore initcall. Until then, all
watermarks are set to zero. This causes cond_accept_memory() to
incorrectly skip memory acceptance because a watermark of 0 is always
met.
To ensure progress, accept one MAX_ORDER page if the watermark is zero.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-and-tested-by: Farrah Chen <farrah.chen@xxxxxxxxx>
Reviewed-by: Pankaj Gupta <pankaj.gupta@xxxxxxx>
Also, did a basic boot test of SNP guest kernel 6.14-rc6 with the patch
applied on top.
---
mm/page_alloc.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 579789600a3c..4fe93029bcb6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7004,7 +7004,7 @@ static inline bool has_unaccepted_memory(void)
static bool cond_accept_memory(struct zone *zone, unsigned int order)
{
- long to_accept;
+ long to_accept, wmark;
bool ret = false;
if (!has_unaccepted_memory())
@@ -7013,8 +7013,18 @@ static bool cond_accept_memory(struct zone *zone, unsigned int order)
if (list_empty(&zone->unaccepted_pages))
return false;
+ wmark = promo_wmark_pages(zone);
+
+ /*
+ * Watermarks have not been initialized yet.
+ *
+ * Accepting one MAX_ORDER page to ensure progress.
+ */
+ if (!wmark)
+ return try_to_accept_memory_one(zone);
+
/* How much to accept to get to promo watermark? */
- to_accept = promo_wmark_pages(zone) -
+ to_accept = wmark -
(zone_page_state(zone, NR_FREE_PAGES) -
__zone_watermark_unusable_free(zone, order, 0) -
zone_page_state(zone, NR_UNACCEPTED));
