linux-kernel - [PATCH v3 1/1] mm/page_alloc: auto-tune watermarks on atomic allocation failure

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Message-ID: <tencent_44B556221480D8371FBC534ACCF3CE2C8707@qq.com>
Date: Mon,  5 Jan 2026 19:59:43 +0800
From: wujing <realwujing@...com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Vlastimil Babka <vbabka@...e.cz>
Cc: Matthew Wilcox <willy@...radead.org>,
	Lance Yang <lance.yang@...ux.dev>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	Brendan Jackman <jackmanb@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Zi Yan <ziy@...dia.com>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	Qiliang Yuan <yuanql9@...natelecom.cn>,
	wujing <realwujing@...com>
Subject: [PATCH v3 1/1] mm/page_alloc: auto-tune watermarks on atomic allocation failure

Introduce a mechanism to dynamically boost watermarks when critical
atomic allocations (GFP_ATOMIC, order-0) fail. This prevents recurring
network packet drops or other atomic failures by proactively triggering
kswapd to reclaim memory for future atomic requests.

The mechanism utilizes the existing watermark_boost infrastructure. When
an order-0 atomic allocation fails, watermarks are boosted in the
relevant zones, which encourages kswapd to reclaim pages more
aggressively. Boosting is debounced to once every 10 seconds to prevent
adjustment storms during burst traffic.

Testing has shown that this allows the system to recover quickly from
sudden spikes in network traffic that otherwise would cause persistent
allocation failures.

Observed failure logs:
[38535641.026406] node 0: slabs: 941, objs: 54656, free: 0
[38535641.037711] node 1: slabs: 349, objs: 22096, free: 272
[38535641.049025] node 1: slabs: 349, objs: 22096, free: 272
[38535642.795972] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC)
[38535642.805017] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0
[38535642.816311] node 0: slabs: 854, objs: 42320, free: 0
[38535642.823066] node 1: slabs: 400, objs: 25360, free: 294
[38535643.070199] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC)
[38535643.078861] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0
[38535643.089719] node 0: slabs: 841, objs: 41824, free: 0
[38535643.096513] node 1: slabs: 393, objs: 24480, free: 272
[38535643.484149] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC)
[38535643.492831] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0
[38535643.503666] node 0: slabs: 898, objs: 43120, free: 159
[38535643.510140] node 1: slabs: 404, objs: 25424, free: 319
[38535644.699224] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC)
[38535644.707911] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0
[38535644.718700] node 0: slabs: 1031, objs: 43328, free: 0
[38535644.725059] node 1: slabs: 339, objs: 17616, free: 317
[38535645.428345] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC)
[38535645.436888] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0
[38535645.447664] node 0: slabs: 940, objs: 40864, free: 144
[38535645.454026] node 1: slabs: 322, objs: 19168, free: 383
[38535645.556122] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC)
[38535645.564576] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0
[38535649.655523] warn_alloc: 59 callbacks suppressed
[38535649.655527] swapper/100: page allocation failure: order:0, mode:0x480020(GFP_ATOMIC), nodemask=(null)
[38535649.671692] swapper/100 cpuset=/ mems_allowed=0-1

Signed-off-by: wujing <realwujing@...com>
Signed-off-by: Qiliang Yuan <yuanql9@...natelecom.cn>
---
 mm/page_alloc.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c380f063e8b7..a2959fee28d9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3975,6 +3975,10 @@ static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
 	mem_cgroup_show_protected_memory(NULL);
 }
 
+/* Auto-tuning watermarks on atomic allocation failures */
+static unsigned long last_boost_jiffies = 0;
+#define BOOST_DEBOUNCE_MS 10000  /* 10 seconds debounce */
+
 void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
 {
 	struct va_format vaf;
@@ -4947,6 +4951,22 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 		goto retry;
 	}
 fail:
+	/* Auto-tuning: boost watermarks if atomic allocation fails */
+	if ((gfp_mask & GFP_ATOMIC) && order == 0) {
+		unsigned long now = jiffies;
+
+		if (time_after(now, last_boost_jiffies + msecs_to_jiffies(BOOST_DEBOUNCE_MS))) {
+			struct zoneref *z;
+			struct zone *zone;
+
+			last_boost_jiffies = now;
+			for_each_zone_zonelist(zone, z, ac->zonelist, ac->highest_zoneidx) {
+				if (boost_watermark(zone))
+					wakeup_kswapd(zone, gfp_mask, 0, ac->highest_zoneidx);
+			}
+		}
+	}
+
 	warn_alloc(gfp_mask, ac->nodemask,
 			"page allocation failure: order:%u", order);
 got_pg:
-- 
2.39.5