From: Shakeel Butt <shakeel.butt@linux.dev>
To: Jiayuan Chen <jiayuan.chen@linux.dev>
Cc: linux-mm@kvack.org, Jiayuan Chen <jiayuan.chen@shopee.com>,
Andrew Morton <akpm@linux-foundation.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Brendan Jackman <jackmanb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>, Zi Yan <ziy@nvidia.com>,
Qi Zheng <zhengqi.arch@bytedance.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] mm/vmscan: add tracepoint and reason for kswapd_failures reset
Date: Sat, 17 Jan 2026 21:08:58 -0800 [thread overview]
Message-ID: <eincfrroi5qp254yv7stkayzy2eayw2zgrjbq2w4icrknkze2l@yodvhzqggxkm> (raw)
In-Reply-To: <20260114074049.229935-3-jiayuan.chen@linux.dev>
On Wed, Jan 14, 2026 at 03:40:36PM +0800, Jiayuan Chen wrote:
> From: Jiayuan Chen <jiayuan.chen@shopee.com>
>
> Currently, kswapd_failures is reset in multiple places (kswapd,
> direct reclaim, PCP freeing, memory-tiers), but there's no way to
> trace when and why it was reset, making it difficult to debug
> memory reclaim issues.
>
> This patch:
>
> 1. Introduce pgdat_reset_kswapd_failures() as a wrapper function to
> centralize kswapd_failures reset logic.
>
> 2. Add reset_kswapd_failures_reason enum to distinguish reset sources:
> - RESET_KSWAPD_FAILURES_KSWAPD: reset from kswapd context
> - RESET_KSWAPD_FAILURES_DIRECT: reset from direct reclaim
> - RESET_KSWAPD_FAILURES_PCP: reset from PCP page freeing
> - RESET_KSWAPD_FAILURES_OTHER: reset from other paths
>
> 3. Add tracepoints for better observability:
> - mm_vmscan_reset_kswapd_failures: traces each reset with reason
> - mm_vmscan_kswapd_reclaim_fail: traces each kswapd reclaim failure
>
> ---
> Test results:
>
> $ trace-cmd record -e vmscan:mm_vmscan_reset_kswapd_failures -e vmscan:mm_vmscan_kswapd_reclaim_fail
> $ # generate memory pressure
> $ trace-cmd report
> cpus=4
> kswapd1-73 [002] 24.863112: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=1
> kswapd1-73 [002] 24.863472: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=2
> kswapd1-73 [002] 24.863813: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=3
> kswapd1-73 [002] 24.864141: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=4
> kswapd1-73 [002] 24.864462: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=5
> kswapd1-73 [002] 24.864779: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=6
> kswapd1-73 [002] 24.865103: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=7
> kswapd1-73 [002] 24.865421: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=8
> kswapd1-73 [002] 24.865737: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=9
> kswapd1-73 [002] 24.866070: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=10
> kswapd1-73 [002] 24.866385: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=11
> kswapd1-73 [002] 24.866701: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=12
> kswapd1-73 [002] 24.867016: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=13
> kswapd1-73 [002] 24.867333: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=14
> kswapd1-73 [002] 24.867649: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=15
> kswapd1-73 [002] 24.867965: mm_vmscan_kswapd_reclaim_fail: nid=1 failures=16
> kswapd0-72 [001] 25.020464: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=1
> kswapd0-72 [001] 25.021054: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=2
> kswapd0-72 [001] 25.021628: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=3
> kswapd0-72 [001] 25.022217: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=4
> kswapd0-72 [001] 25.022790: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=5
> kswapd0-72 [001] 25.023366: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=6
> kswapd0-72 [001] 25.023937: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=7
> kswapd0-72 [001] 25.024511: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=8
> kswapd0-72 [001] 25.025092: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=9
> kswapd0-72 [001] 25.025665: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=10
> kswapd0-72 [001] 25.026249: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=11
> kswapd0-72 [001] 25.026824: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=12
> kswapd0-72 [001] 25.027398: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=13
> kswapd0-72 [001] 25.027976: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=14
> kswapd0-72 [001] 25.028554: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=15
> kswapd0-72 [001] 25.029140: mm_vmscan_kswapd_reclaim_fail: nid=0 failures=16
> ann-416 [002] 25.577925: mm_vmscan_reset_kswapd_failures: nid=0 reason=PCP
> dd-417 [002] 35.111721: mm_vmscan_reset_kswapd_failures: nid=1 reason=DIRECT
>
> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
> Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Thanks for adding this.
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
next prev parent reply other threads:[~2026-01-18 5:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-14 7:40 [PATCH v3 0/2] mm/vmscan: mitigate spurious kswapd_failures reset and add tracepoints Jiayuan Chen
2026-01-14 7:40 ` [PATCH v3 1/2] mm/vmscan: mitigate spurious kswapd_failures reset from direct reclaim Jiayuan Chen
2026-01-16 17:00 ` Johannes Weiner
2026-01-19 3:04 ` Jiayuan Chen
2026-01-18 5:04 ` Shakeel Butt
2026-01-14 7:40 ` [PATCH v3 2/2] mm/vmscan: add tracepoint and reason for kswapd_failures reset Jiayuan Chen
2026-01-18 5:08 ` Shakeel Butt [this message]
2026-01-15 23:39 ` [PATCH v3 0/2] mm/vmscan: mitigate spurious kswapd_failures reset and add tracepoints Andrew Morton
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