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Message-ID: <20230222190718.GR2948950@paulmck-ThinkPad-P17-Gen-1>
Date: Wed, 22 Feb 2023 11:07:18 -0800
From: "Paul E. McKenney" <paulmck@...nel.org>
To: John Stultz <jstultz@...gle.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Davidlohr Bueso <dave@...olabs.net>,
Josh Triplett <josh@...htriplett.org>,
Joel Fernandes <joel@...lfernandes.org>,
Juri Lelli <juri.lelli@...hat.com>,
Valentin Schneider <vschneid@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
kernel-team@...roid.com, Connor O'Brien <connoro@...gle.com>
Subject: Re: [PATCH v4 1/4] locktorture: Add nested_[un]lock() hooks and
nlocks parameter
On Tue, Feb 21, 2023 at 07:02:35PM +0000, John Stultz wrote:
> In order to extend locktorture to support lock nesting, add
> nested_lock() and nested_unlock() hooks to the torture ops.
>
> These take a 32bit lockset mask which is generated at random,
> so some number of locks will be taken before the main lock is
> taken and released afterwards.
>
> Additionally, add nested_locks module parameter to allow
> specifying the number of nested locks to be used.
>
> This has been helpful to uncover issues in the proxy-exec
> series development.
>
> This was inspired by locktorture extensions originally implemented
> by Connor O'Brien, for stress testing the proxy-execution series:
> https://lore.kernel.org/lkml/20221003214501.2050087-12-connoro@google.com/
>
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Cc: "Paul E. McKenney" <paulmck@...nel.org>
> Cc: Josh Triplett <josh@...htriplett.org>
> Cc: Joel Fernandes <joel@...lfernandes.org>
> Cc: Juri Lelli <juri.lelli@...hat.com>
> Cc: Valentin Schneider <vschneid@...hat.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> Cc: kernel-team@...roid.com
> Reviewed-by: Davidlohr Bueso <dave@...olabs.net>
> Co-developed-by: Connor O'Brien <connoro@...gle.com>
> Signed-off-by: Connor O'Brien <connoro@...gle.com>
> Signed-off-by: John Stultz <jstultz@...gle.com>
I queued this series in place of its precedessor, thank you for the
update!
Given what I know now, I will set this up for the v6.4 merge window.
Thanx, Paul
> ---
> v3:
> * Minor commit message tweaks and naming changes
> suggested by Davidlohr Bueso
> v4:
> * Add co-developed tag
> ---
> kernel/locking/locktorture.c | 23 +++++++++++++++++++----
> 1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
> index 9c2fb613a55d..6fe046594868 100644
> --- a/kernel/locking/locktorture.c
> +++ b/kernel/locking/locktorture.c
> @@ -48,6 +48,9 @@ torture_param(int, stat_interval, 60,
> torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
> torture_param(int, verbose, 1,
> "Enable verbose debugging printk()s");
> +torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
> +/* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */
> +#define MAX_NESTED_LOCKS 8
>
> static char *torture_type = "spin_lock";
> module_param(torture_type, charp, 0444);
> @@ -76,10 +79,12 @@ static void lock_torture_cleanup(void);
> struct lock_torture_ops {
> void (*init)(void);
> void (*exit)(void);
> + int (*nested_lock)(int tid, u32 lockset);
> int (*writelock)(int tid);
> void (*write_delay)(struct torture_random_state *trsp);
> void (*task_boost)(struct torture_random_state *trsp);
> void (*writeunlock)(int tid);
> + void (*nested_unlock)(int tid, u32 lockset);
> int (*readlock)(int tid);
> void (*read_delay)(struct torture_random_state *trsp);
> void (*readunlock)(int tid);
> @@ -669,6 +674,7 @@ static int lock_torture_writer(void *arg)
> struct lock_stress_stats *lwsp = arg;
> int tid = lwsp - cxt.lwsa;
> DEFINE_TORTURE_RANDOM(rand);
> + u32 lockset_mask;
>
> VERBOSE_TOROUT_STRING("lock_torture_writer task started");
> set_user_nice(current, MAX_NICE);
> @@ -677,7 +683,10 @@ static int lock_torture_writer(void *arg)
> if ((torture_random(&rand) & 0xfffff) == 0)
> schedule_timeout_uninterruptible(1);
>
> + lockset_mask = torture_random(&rand);
> cxt.cur_ops->task_boost(&rand);
> + if (cxt.cur_ops->nested_lock)
> + cxt.cur_ops->nested_lock(tid, lockset_mask);
> cxt.cur_ops->writelock(tid);
> if (WARN_ON_ONCE(lock_is_write_held))
> lwsp->n_lock_fail++;
> @@ -690,6 +699,8 @@ static int lock_torture_writer(void *arg)
> lock_is_write_held = false;
> WRITE_ONCE(last_lock_release, jiffies);
> cxt.cur_ops->writeunlock(tid);
> + if (cxt.cur_ops->nested_unlock)
> + cxt.cur_ops->nested_unlock(tid, lockset_mask);
>
> stutter_wait("lock_torture_writer");
> } while (!torture_must_stop());
> @@ -830,11 +841,11 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
> const char *tag)
> {
> pr_alert("%s" TORTURE_FLAG
> - "--- %s%s: nwriters_stress=%d nreaders_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
> + "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
> torture_type, tag, cxt.debug_lock ? " [debug]": "",
> - cxt.nrealwriters_stress, cxt.nrealreaders_stress, stat_interval,
> - verbose, shuffle_interval, stutter, shutdown_secs,
> - onoff_interval, onoff_holdoff);
> + cxt.nrealwriters_stress, cxt.nrealreaders_stress,
> + nested_locks, stat_interval, verbose, shuffle_interval,
> + stutter, shutdown_secs, onoff_interval, onoff_holdoff);
> }
>
> static void lock_torture_cleanup(void)
> @@ -1053,6 +1064,10 @@ static int __init lock_torture_init(void)
> }
> }
>
> + /* cap nested_locks to MAX_NESTED_LOCKS */
> + if (nested_locks > MAX_NESTED_LOCKS)
> + nested_locks = MAX_NESTED_LOCKS;
> +
> if (cxt.cur_ops->readlock) {
> reader_tasks = kcalloc(cxt.nrealreaders_stress,
> sizeof(reader_tasks[0]),
> --
> 2.39.2.637.g21b0678d19-goog
>
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