From: Steven Rostedt <rostedt@goodmis.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
David Stevens <stevensd@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Thomas Gleixner <tglx@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Chinner <david@fromorbit.com>, Qi Zheng <qi.zheng@linux.dev>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Uladzislau Rezki <urezki@gmail.com>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R . Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Kees Cook <kees@kernel.org>,
Clark Williams <clrkwllms@kernel.org>,
suleiman@google.com, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-rt-devel@lists.linux.dev
Subject: Re: [RFC 06/10] Reclaim memory from blocked kernel stacks
Date: Fri, 28 Aug 2026 15:13:13 -0400 [thread overview]
Message-ID: <20260828151313.5c4a5e4b@gandalf.local.home> (raw)
In-Reply-To: <20260828150836.2d5b378c@gandalf.local.home>
On Fri, 28 Aug 2026 15:08:36 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> If you want to see how big your stack is and where its used, you can run
> the stack tracer:
>
> # trace-cmd stack --start
>
> [wait]
>
> # trace-cmd stack
> (stack tracer running)
> Depth Size Location (41 entries)
> ----- ---- --------
> 0) 5032 48 choose_idle_cpu+0x5/0x100
> 1) 4984 296 select_task_rq_fair+0xa84/0x2b40
> 2) 4688 104 try_to_wake_up+0x168/0x7e0
> 3) 4584 16 task_work_add+0xd7/0xf0
> 4) 4568 16 io_req_normal_work_add+0x75/0xb0
> 5) 4552 40 io_poll_wake+0x10f/0x160
> 6) 4512 64 __wake_up_common+0x72/0xa0
> 7) 4448 40 __wake_up_sync_key+0x43/0x60
> 8) 4408 24 sock_def_readable+0x46/0xe0
> 9) 4384 80 tun_net_xmit+0x240/0x550 [tun]
> 10) 4304 80 dev_hard_start_xmit+0x63/0x1e0
> 11) 4224 256 __dev_queue_xmit+0x880/0x10b0
> 12) 3968 24 br_dev_queue_push_xmit+0x62/0xf0 [bridge]
> 13) 3944 80 br_dev_xmit+0x15e/0x4a0 [bridge]
> 14) 3864 80 dev_hard_start_xmit+0x63/0x1e0
> 15) 3784 256 __dev_queue_xmit+0x880/0x10b0
> 16) 3528 72 ip_finish_output2+0x2ce/0x650
> 17) 3456 104 ip_output+0x63/0x110
> 18) 3352 72 __ip_queue_xmit+0x16f/0x470
> 19) 3280 232 __tcp_transmit_skb+0xcb5/0x1140
> 20) 3048 120 tcp_write_xmit+0x5aa/0x1760
> 21) 2928 24 __tcp_push_pending_frames+0x39/0x110
> 22) 2904 104 tcp_rcv_established+0x37f/0xeb0
> 23) 2800 32 tcp_v4_do_rcv+0x13f/0x300
> 24) 2768 168 tcp_v4_rcv+0xc01/0x1300
> 25) 2600 48 ip_protocol_deliver_rcu+0x35/0x1b0
> 26) 2552 24 ip_local_deliver_finish+0x85/0x100
> 27) 2528 40 __netif_receive_skb_one_core+0x85/0xa0
> 28) 2488 56 netif_receive_skb+0x127/0x180
> 29) 2432 104 br_handle_frame_finish+0x428/0x680 [bridge]
> 30) 2328 40 br_handle_frame+0x132/0x2a0 [bridge]
> 31) 2288 280 __netif_receive_skb_core.constprop.0+0x16e/0xdf0
> 32) 2008 40 __netif_receive_skb_one_core+0x39/0xa0
> 33) 1968 56 netif_receive_skb+0x127/0x180
> 34) 1912 256 tun_get_user+0xbd0/0x1260 [tun]
> 35) 1656 56 tun_chr_write_iter+0x77/0xba [tun]
> 36) 1600 88 do_iter_readv_writev+0x161/0x260
> 37) 1512 256 vfs_writev+0x168/0x3c0
> 38) 1256 80 do_writev+0x7f/0x110
> 39) 1176 984 do_syscall_64+0xaa/0x670
If one worries about stack size, they may want to turn off
CONFIG_RANDOMIZE_KSTACK_OFFSET as I see some big numbers for do_syscall_64()
-- Steve
> 40) 192 192 entry_SYSCALL_64_after_hwframe+0x76/0x7e
next prev parent reply other threads:[~2026-08-28 19:12 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-27 23:29 [RFC 00/10] Reclaimable kernel stacks David Stevens
2026-08-27 23:29 ` [RFC 01/10] Add !MEMCG memcg_list_lru_alloc implementation David Stevens
2026-08-27 23:29 ` [RFC 02/10] mm/vmalloc: Skip vmallocinfo NUMA stats for VM_SPARSE David Stevens
2026-08-27 23:29 ` [RFC 03/10] fork: refactor vmap stack alloc/free into helpers David Stevens
2026-08-27 23:29 ` [RFC 04/10] mm: vmalloc: support creating aligned vm areas David Stevens
2026-08-27 23:29 ` [RFC 05/10] fork: allocate reclaimable stacks with VM_SPARSE David Stevens
2026-08-27 23:29 ` [RFC 06/10] Reclaim memory from blocked kernel stacks David Stevens
2026-08-28 11:54 ` Peter Zijlstra
2026-08-28 12:01 ` Peter Zijlstra
2026-08-28 12:04 ` Peter Zijlstra
2026-08-29 0:18 ` David Stevens
2026-08-29 8:39 ` Peter Zijlstra
2026-08-29 8:43 ` Peter Zijlstra
2026-08-31 17:44 ` David Stevens
2026-08-28 12:41 ` Peter Zijlstra
2026-08-28 12:57 ` Peter Zijlstra
2026-08-28 23:33 ` David Stevens
2026-08-28 13:36 ` Sebastian Andrzej Siewior
2026-08-28 13:59 ` Peter Zijlstra
2026-08-28 14:25 ` Peter Zijlstra
2026-08-28 15:58 ` Sebastian Andrzej Siewior
2026-08-28 15:10 ` Sebastian Andrzej Siewior
2026-08-28 19:08 ` Steven Rostedt
2026-08-28 19:13 ` Steven Rostedt [this message]
2026-08-28 19:17 ` Steven Rostedt
2026-08-31 6:55 ` Sebastian Andrzej Siewior
2026-08-31 7:07 ` Peter Zijlstra
2026-08-31 15:13 ` Steven Rostedt
2026-09-01 12:32 ` Peter Zijlstra
2026-09-01 12:01 ` Will Deacon
2026-08-28 20:50 ` David Stevens
2026-08-29 8:49 ` Peter Zijlstra
2026-08-29 14:49 ` Matthew Wilcox
2026-08-31 7:14 ` Peter Zijlstra
2026-08-31 7:36 ` Sebastian Andrzej Siewior
2026-08-31 14:03 ` Vlastimil Babka (SUSE)
2026-08-31 14:19 ` Sebastian Andrzej Siewior
2026-08-28 21:17 ` David Stevens
2026-08-31 8:08 ` Sebastian Andrzej Siewior
2026-08-31 18:20 ` David Stevens
2026-08-27 23:29 ` [RFC 07/10] Reclaim stacks via a shrinker David Stevens
2026-08-27 23:29 ` [RFC 08/10] Set PF_RECLAIMABLE_STACK in various places David Stevens
2026-08-28 6:33 ` K Prateek Nayak
2026-09-01 9:27 ` Alice Ryhl
2026-08-27 23:29 ` [RFC 09/10] x86: Enable reclaimable stacks David Stevens
2026-08-27 23:29 ` [RFC 10/10] arm64: " David Stevens
2026-08-28 12:47 ` [RFC 00/10] Reclaimable kernel stacks Peter Zijlstra
2026-08-28 14:33 ` Steven Rostedt
2026-08-28 14:35 ` Peter Zijlstra
2026-08-28 14:45 ` Peter Zijlstra
2026-08-28 16:10 ` Steven Rostedt
2026-08-28 17:58 ` David Stevens
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