b88f55389a
The kernel sleep profile is no longer working due to a recursive locking
bug introduced by commit 42a20f86dc19 ("sched: Add wrapper for get_wchan()
to keep task blocked")
Booting with the 'profile=sleep' kernel command line option added or
executing
# echo -n sleep > /sys/kernel/profiling
after boot causes the system to lock up.
Lockdep reports
kthreadd/3 is trying to acquire lock:
ffff93ac82e08d58 (&p->pi_lock){....}-{2:2}, at: get_wchan+0x32/0x70
but task is already holding lock:
ffff93ac82e08d58 (&p->pi_lock){....}-{2:2}, at: try_to_wake_up+0x53/0x370
with the call trace being
lock_acquire+0xc8/0x2f0
get_wchan+0x32/0x70
__update_stats_enqueue_sleeper+0x151/0x430
enqueue_entity+0x4b0/0x520
enqueue_task_fair+0x92/0x6b0
ttwu_do_activate+0x73/0x140
try_to_wake_up+0x213/0x370
swake_up_locked+0x20/0x50
complete+0x2f/0x40
kthread+0xfb/0x180
However, since nobody noticed this regression for more than two years,
let's remove 'profile=sleep' support based on the assumption that nobody
needs this functionality.
Fixes: 42a20f86dc19 ("sched: Add wrapper for get_wchan() to keep task blocked")
Cc: stable@vger.kernel.org # v5.16+
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
85 lines
1.4 KiB
C
85 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_PROFILE_H
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#define _LINUX_PROFILE_H
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/cache.h>
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#include <asm/errno.h>
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#define CPU_PROFILING 1
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#define SCHED_PROFILING 2
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#define KVM_PROFILING 4
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struct proc_dir_entry;
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struct notifier_block;
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#if defined(CONFIG_PROFILING) && defined(CONFIG_PROC_FS)
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int create_proc_profile(void);
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#else
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static inline int create_proc_profile(void)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_PROFILING
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extern int prof_on __read_mostly;
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/* init basic kernel profiler */
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int profile_init(void);
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int profile_setup(char *str);
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void profile_tick(int type);
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int setup_profiling_timer(unsigned int multiplier);
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/*
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* Add multiple profiler hits to a given address:
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*/
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void profile_hits(int type, void *ip, unsigned int nr_hits);
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/*
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* Single profiler hit:
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*/
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static inline void profile_hit(int type, void *ip)
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{
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/*
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* Speedup for the common (no profiling enabled) case:
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*/
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if (unlikely(prof_on == type))
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profile_hits(type, ip, 1);
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}
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struct task_struct;
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struct mm_struct;
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#else
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#define prof_on 0
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static inline int profile_init(void)
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{
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return 0;
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}
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static inline void profile_tick(int type)
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{
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return;
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}
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static inline void profile_hits(int type, void *ip, unsigned int nr_hits)
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{
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return;
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}
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static inline void profile_hit(int type, void *ip)
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{
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return;
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}
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#endif /* CONFIG_PROFILING */
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#endif /* _LINUX_PROFILE_H */
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