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From: Stefan Metzmacher <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Cc: Stefan Metzmacher <[email protected]>
Subject: [PATCH v3 5/6] io-wq: warn about future set_task_comm() overflows.
Date: Sun, 25 Apr 2021 01:26:07 +0200	[thread overview]
Message-ID: <94254f497b59e7fda85503c643ec5a2e25a30c0d.1619306115.git.metze@samba.org> (raw)
In-Reply-To: <[email protected]>

Signed-off-by: Stefan Metzmacher <[email protected]>
---
 fs/io-wq.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index cd1af924c3d1..b80c5d905127 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -640,7 +640,19 @@ static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
 		return;
 	}
 
-	snprintf(tsk_comm, sizeof(tsk_comm), "iou-wrk-%d", wq->task->pid);
+	/*
+	 * The limit value of pid_max_max/PID_MAX_LIMIT
+	 * is 4 * 1024 * 1024 = 4194304.
+	 *
+	 * TASK_COMM_LEN is 16, so we have 15 chars to fill.
+	 *
+	 * With "iou-wrk-4194304" we just fit into 15 chars.
+	 * If that ever changes we may better add some special
+	 * handling for PF_IO_WORKER in proc_task_name(), as that
+	 * allows up to 63 chars.
+	 */
+	WARN_ON(snprintf(tsk_comm, sizeof(tsk_comm),
+			 "iou-wrk-%d", wq->task->pid) >= sizeof(tsk_comm));
 	set_task_comm(tsk, tsk_comm);
 
 	tsk->pf_io_worker = worker;
-- 
2.25.1


  parent reply	other threads:[~2021-04-24 23:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-24 23:26 [PATCH v3 0/6] Complete setup before calling wake_up_new_task() Stefan Metzmacher
2021-04-24 23:26 ` [PATCH v3 1/6] kernel: always initialize task->pf_io_worker to NULL Stefan Metzmacher
2021-04-24 23:26 ` [PATCH v3 2/6] io_uring: io_sq_thread() no longer needs to reset current->pf_io_worker Stefan Metzmacher
2021-04-24 23:26 ` [PATCH v3 3/6] io-wq: call set_task_comm() before wake_up_new_task() Stefan Metzmacher
2021-04-24 23:26 ` [PATCH v3 4/6] io_uring: complete sq_thread setup before calling wake_up_new_task() Stefan Metzmacher
2021-04-24 23:26 ` Stefan Metzmacher [this message]
2021-04-25  0:08   ` [PATCH v3 5/6] io-wq: warn about future set_task_comm() overflows Pavel Begunkov
2021-04-24 23:26 ` [PATCH v3 6/6] io_uring: " Stefan Metzmacher
2021-04-25 16:28 ` [PATCH v3 0/6] Complete setup before calling wake_up_new_task() Jens Axboe
2021-04-26 16:01   ` Stefan Metzmacher

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