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FAILED: patch "[PATCH] sched_ext: Pass held rq to SCX_CALL_OP() for" failed to apply to 7.0-stable tree

PATCH [email protected] 1 participant 1 message May 12

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The patch below does not apply to the 7.0-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-7.0.y
git checkout FETCH_HEAD
git cherry-pick -x 207d76a372fb1bb324eadc8cb5bcaa0a8da7cefd
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051223-reference-armadillo-27f4@gregkh' --subject-prefix 'PATCH 7.0.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 207d76a372fb1bb324eadc8cb5bcaa0a8da7cefd Mon Sep 17 00:00:00 2001
From: Tejun Heo <[email protected]>
Date: Fri, 24 Apr 2026 14:31:36 -1000
Subject: [PATCH] sched_ext: Pass held rq to SCX_CALL_OP() for
dump_cpu/dump_task

scx_dump_state() walks CPUs with rq_lock_irqsave() held and invokes ops.dump_cpu / ops.dump_task with NULL locked_rq, leaving scx_locked_rq_state NULL. If the BPF callback calls a kfunc that re-acquires rq based on scx_locked_rq() - e.g. scx_bpf_cpuperf_set(cpu)
- it re-acquires the already-held rq.

Pass the held rq to SCX_CALL_OP(). Thread it into scx_dump_task() too. The pre-loop ops.dump call runs before rq_lock_irqsave() so keeps rq=NULL.

Fixes 07814a9439a3 ("sched_ext: Print debug dump after an error exit")
Cc [email protected] # v6.12+
Reported-by Chris Mason <[email protected]>
Signed-off-by Tejun Heo <[email protected]>
Reviewed-by Andrea Righi <[email protected]>
kernel/sched/ext.c +6 -8
index 26968d0a6752..73d629559d6d 100644
@@ -6117,9 +6117,8 @@ static void ops_dump_exit(void)
 	scx_dump_data.cpu = -1;
 }
 
-static void scx_dump_task(struct scx_sched *sch,
-			  struct seq_buf *s, struct scx_dump_ctx *dctx,
-			  struct task_struct *p, char marker)
+static void scx_dump_task(struct scx_sched *sch, struct seq_buf *s, struct scx_dump_ctx *dctx,
+			  struct rq *rq, struct task_struct *p, char marker)
 {
 	static unsigned long bt[SCX_EXIT_BT_LEN];
 	struct scx_sched *task_sch = scx_task_sched(p);

@@ -6160,7 +6159,7 @@ static void scx_dump_task(struct scx_sched *sch,
 
 	if (SCX_HAS_OP(sch, dump_task)) {
 		ops_dump_init(s, "    ");
-		SCX_CALL_OP(sch, dump_task, NULL, dctx, p);
+		SCX_CALL_OP(sch, dump_task, rq, dctx, p);
 		ops_dump_exit();
 	}
 

@@ -6284,8 +6283,7 @@ static void scx_dump_state(struct scx_sched *sch, struct scx_exit_info *ei,
 		used = seq_buf_used(&ns);
 		if (SCX_HAS_OP(sch, dump_cpu)) {
 			ops_dump_init(&ns, "  ");
-			SCX_CALL_OP(sch, dump_cpu, NULL,
-				    &dctx, cpu, idle);
+			SCX_CALL_OP(sch, dump_cpu, rq, &dctx, cpu, idle);
 			ops_dump_exit();
 		}
 

@@ -6308,11 +6306,11 @@ static void scx_dump_state(struct scx_sched *sch, struct scx_exit_info *ei,
 
 		if (rq->curr->sched_class == &ext_sched_class &&
 		    (dump_all_tasks || scx_task_on_sched(sch, rq->curr)))
-			scx_dump_task(sch, &s, &dctx, rq->curr, '*');
+			scx_dump_task(sch, &s, &dctx, rq, rq->curr, '*');
 
 		list_for_each_entry(p, &rq->scx.runnable_list, scx.runnable_node)
 			if (dump_all_tasks || scx_task_on_sched(sch, p))
-				scx_dump_task(sch, &s, &dctx, p, ' ');
+				scx_dump_task(sch, &s, &dctx, rq, p, ' ');
 	next:
 		rq_unlock_irqrestore(rq, &rf);
 	}