From: Tejun Heo <tj@kernel.org>
To: torvalds@linux-foundation.org, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, vschneid@redhat.com, ast@kernel.org,
daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org,
joshdon@google.com, brho@google.com, pjt@google.com,
derkling@google.com, haoluo@google.com, dvernet@meta.com,
dschatzberg@meta.com, dskarlat@cs.cmu.edu, riel@surriel.com,
changwoo@igalia.com, himadrics@inria.fr, memxor@gmail.com
Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
kernel-team@meta.com, David Vernet <void@manifault.com>,
Tejun Heo <tj@kernel.org>
Subject: [PATCH 18/36] sched_ext: Print sched_ext info when dumping stack
Date: Fri, 10 Nov 2023 16:47:44 -1000 [thread overview]
Message-ID: <20231111024835.2164816-19-tj@kernel.org> (raw)
In-Reply-To: <20231111024835.2164816-1-tj@kernel.org>
From: David Vernet <void@manifault.com>
It would be useful to see what the sched_ext scheduler state is, and what
scheduler is running, when we're dumping a task's stack. This patch
therefore adds a new print_scx_info() function that's called in the same
context as print_worker_info() and print_stop_info(). An example dump
follows.
BUG: kernel NULL pointer dereference, address: 0000000000000999
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] PREEMPT SMP
CPU: 13 PID: 2047 Comm: insmod Tainted: G O 6.6.0-work-10323-gb58d4cae8e99-dirty #34
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 2/2/2022
Sched_ext: qmap (enabled+all), task: runnable_at=-17ms
RIP: 0010:init_module+0x9/0x1000 [test_module]
...
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
include/linux/sched/ext.h | 2 ++
kernel/sched/core.c | 1 +
kernel/sched/ext.c | 45 +++++++++++++++++++++++++++++++++++++++
lib/dump_stack.c | 1 +
4 files changed, 49 insertions(+)
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h
index 9d41acaf89c0..55f649bd065c 100644
--- a/include/linux/sched/ext.h
+++ b/include/linux/sched/ext.h
@@ -428,10 +428,12 @@ struct sched_ext_entity {
};
void sched_ext_free(struct task_struct *p);
+void print_scx_info(const char *log_lvl, struct task_struct *p);
#else /* !CONFIG_SCHED_CLASS_EXT */
static inline void sched_ext_free(struct task_struct *p) {}
+static inline void print_scx_info(const char *log_lvl, struct task_struct *p) {}
#endif /* CONFIG_SCHED_CLASS_EXT */
#endif /* _LINUX_SCHED_EXT_H */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1906f8397c28..957ae28a6e3f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9217,6 +9217,7 @@ void sched_show_task(struct task_struct *p)
print_worker_info(KERN_INFO, p);
print_stop_info(KERN_INFO, p);
+ print_scx_info(KERN_INFO, p);
show_stack(p, NULL, KERN_INFO);
put_task_stack(p);
}
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 4e2aa9f308fb..65ee99ea111b 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -2787,6 +2787,51 @@ static const struct sysrq_key_op sysrq_sched_ext_reset_op = {
.enable_mask = SYSRQ_ENABLE_RTNICE,
};
+/**
+ * print_scx_info - print out sched_ext scheduler state
+ * @log_lvl: the log level to use when printing
+ * @p: target task
+ *
+ * If a sched_ext scheduler is enabled, print the name and state of the
+ * scheduler. If @p is on sched_ext, print further information about the task.
+ *
+ * This function can be safely called on any task as long as the task_struct
+ * itself is accessible. While safe, this function isn't synchronized and may
+ * print out mixups or garbages of limited length.
+ */
+void print_scx_info(const char *log_lvl, struct task_struct *p)
+{
+ enum scx_ops_enable_state state = scx_ops_enable_state();
+ const char *all = READ_ONCE(scx_switching_all) ? "+all" : "";
+ char runnable_at_buf[22] = "?";
+ struct sched_class *class;
+ unsigned long runnable_at;
+
+ if (state == SCX_OPS_DISABLED)
+ return;
+
+ /*
+ * Carefully check if the task was running on sched_ext, and then
+ * carefully copy the time it's been runnable, and its state.
+ */
+ if (copy_from_kernel_nofault(&class, &p->sched_class, sizeof(class)) ||
+ class != &ext_sched_class) {
+ printk("%sSched_ext: %s (%s%s)", log_lvl, scx_ops.name,
+ scx_ops_enable_state_str[state], all);
+ return;
+ }
+
+ if (!copy_from_kernel_nofault(&runnable_at, &p->scx.runnable_at,
+ sizeof(runnable_at)))
+ scnprintf(runnable_at_buf, sizeof(runnable_at_buf), "%+lldms",
+ (s64)(runnable_at - jiffies) * (HZ / MSEC_PER_SEC));
+
+ /* Print everything onto one line to conserve console spce. */
+ printk("%sSched_ext: %s (%s%s), task: runnable_at=%s",
+ log_lvl, scx_ops.name, scx_ops_enable_state_str[state], all,
+ runnable_at_buf);
+}
+
void __init init_sched_ext_class(void)
{
int cpu;
diff --git a/lib/dump_stack.c b/lib/dump_stack.c
index 83471e81501a..6e667c445539 100644
--- a/lib/dump_stack.c
+++ b/lib/dump_stack.c
@@ -68,6 +68,7 @@ void dump_stack_print_info(const char *log_lvl)
print_worker_info(log_lvl, current);
print_stop_info(log_lvl, current);
+ print_scx_info(log_lvl, current);
}
/**
--
2.42.0
next prev parent reply other threads:[~2023-11-11 2:50 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-11 2:47 [PATCHSET v5] sched: Implement BPF extensible scheduler class Tejun Heo
2023-11-11 2:47 ` [PATCH 01/36] cgroup: Implement cgroup_show_cftypes() Tejun Heo
2023-11-11 2:47 ` [PATCH 02/36] sched: Restructure sched_class order sanity checks in sched_init() Tejun Heo
2023-11-11 2:47 ` [PATCH 03/36] sched: Allow sched_cgroup_fork() to fail and introduce sched_cancel_fork() Tejun Heo
2023-11-11 2:47 ` [PATCH 04/36] sched: Add sched_class->reweight_task() Tejun Heo
2023-11-11 2:47 ` [PATCH 05/36] sched: Add sched_class->switching_to() and expose check_class_changing/changed() Tejun Heo
2023-11-11 2:47 ` [PATCH 06/36] sched: Factor out cgroup weight conversion functions Tejun Heo
2023-11-11 2:47 ` [PATCH 07/36] sched: Expose css_tg() and __setscheduler_prio() Tejun Heo
2023-11-11 2:47 ` [PATCH 08/36] sched: Enumerate CPU cgroup file types Tejun Heo
2023-11-11 2:47 ` [PATCH 09/36] sched: Add @reason to sched_class->rq_{on|off}line() Tejun Heo
2023-11-11 2:47 ` [PATCH 10/36] sched: Add normal_policy() Tejun Heo
2023-11-11 2:47 ` [PATCH 11/36] sched_ext: Add boilerplate for extensible scheduler class Tejun Heo
2023-11-11 2:47 ` [PATCH 12/36] sched_ext: Implement BPF " Tejun Heo
2023-11-13 13:34 ` Changwoo Min
2023-11-14 19:07 ` Tejun Heo
2023-11-13 20:04 ` Andrea Righi
2023-11-14 19:07 ` Tejun Heo
2023-11-23 8:07 ` Andrea Righi
2023-11-25 19:59 ` Tejun Heo
2023-11-26 9:05 ` Andrea Righi
2023-12-07 2:04 ` [PATCH] scx: set p->scx.ops_state using atomic_long_set_release Changwoo Min
2023-12-08 0:16 ` Tejun Heo
2024-03-23 2:37 ` [PATCH 12/36] sched_ext: Implement BPF extensible scheduler class Joel Fernandes
2024-03-23 22:12 ` Tejun Heo
2024-04-25 21:28 ` Joel Fernandes
2024-04-26 16:57 ` Barret Rhoden
2024-04-26 21:58 ` Tejun Heo
2023-11-11 2:47 ` [PATCH 13/36] sched_ext: Add scx_simple and scx_example_qmap example schedulers Tejun Heo
2023-11-12 4:17 ` kernel test robot
2023-11-12 18:06 ` Tejun Heo
2023-11-11 2:47 ` [PATCH 14/36] sched_ext: Add sysrq-S which disables the BPF scheduler Tejun Heo
2023-11-11 2:47 ` [PATCH 15/36] sched_ext: Implement runnable task stall watchdog Tejun Heo
2023-11-11 2:47 ` [PATCH 16/36] sched_ext: Allow BPF schedulers to disallow specific tasks from joining SCHED_EXT Tejun Heo
2023-11-11 2:47 ` [PATCH 17/36] sched_ext: Allow BPF schedulers to switch all eligible tasks into sched_ext Tejun Heo
2023-11-11 2:47 ` Tejun Heo [this message]
2023-11-14 19:23 ` [PATCH v2 18/36] sched_ext: Print sched_ext info when dumping stack Tejun Heo
2023-11-11 2:47 ` [PATCH 19/36] sched_ext: Implement scx_bpf_kick_cpu() and task preemption support Tejun Heo
2023-11-11 2:47 ` [PATCH 20/36] sched_ext: Add a central scheduler which makes all scheduling decisions on one CPU Tejun Heo
2023-11-11 2:47 ` [PATCH 21/36] sched_ext: Make watchdog handle ops.dispatch() looping stall Tejun Heo
2023-11-11 2:47 ` [PATCH 22/36] sched_ext: Add task state tracking operations Tejun Heo
2023-11-11 2:47 ` [PATCH 23/36] sched_ext: Implement tickless support Tejun Heo
2023-11-11 2:47 ` [PATCH 24/36] sched_ext: Track tasks that are subjects of the in-flight SCX operation Tejun Heo
2023-11-11 2:47 ` [PATCH 25/36] sched_ext: Add cgroup support Tejun Heo
2023-11-11 2:47 ` [PATCH 26/36] sched_ext: Add a cgroup-based core-scheduling scheduler Tejun Heo
2023-11-11 2:47 ` [PATCH 27/36] sched_ext: Add a cgroup scheduler which uses flattened hierarchy Tejun Heo
2023-11-11 2:47 ` [PATCH 28/36] sched_ext: Implement SCX_KICK_WAIT Tejun Heo
2023-11-11 2:47 ` [PATCH 29/36] sched_ext: Implement sched_ext_ops.cpu_acquire/release() Tejun Heo
2023-11-11 2:47 ` [PATCH 30/36] sched_ext: Implement sched_ext_ops.cpu_online/offline() Tejun Heo
2023-11-11 2:47 ` [PATCH 31/36] sched_ext: Implement core-sched support Tejun Heo
2023-11-11 2:47 ` [PATCH 32/36] sched_ext: Add vtime-ordered priority queue to dispatch_q's Tejun Heo
2023-11-11 2:47 ` [PATCH 33/36] sched_ext: Documentation: scheduler: Document extensible scheduler class Tejun Heo
2023-11-11 2:48 ` [PATCH 34/36] sched_ext: Add a basic, userland vruntime scheduler Tejun Heo
2023-11-11 2:48 ` [PATCH 35/36] sched_ext: Add scx_rusty, a rust userspace hybrid scheduler Tejun Heo
2023-11-11 2:48 ` [PATCH 36/36] sched_ext: Add scx_layered, a highly configurable multi-layer scheduler Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231111024835.2164816-19-tj@kernel.org \
--to=tj@kernel.org \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=brho@google.com \
--cc=bristot@redhat.com \
--cc=bsegall@google.com \
--cc=changwoo@igalia.com \
--cc=daniel@iogearbox.net \
--cc=derkling@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=dschatzberg@meta.com \
--cc=dskarlat@cs.cmu.edu \
--cc=dvernet@meta.com \
--cc=haoluo@google.com \
--cc=himadrics@inria.fr \
--cc=joshdon@google.com \
--cc=juri.lelli@redhat.com \
--cc=kernel-team@meta.com \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.lau@kernel.org \
--cc=memxor@gmail.com \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=pjt@google.com \
--cc=riel@surriel.com \
--cc=rostedt@goodmis.org \
--cc=torvalds@linux-foundation.org \
--cc=vincent.guittot@linaro.org \
--cc=void@manifault.com \
--cc=vschneid@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).