From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kernel/locking: Add context to ww_mutex_trylock.
Date: Thu, 9 Sep 2021 07:38:06 +0200 [thread overview]
Message-ID: <96ab9cf1-250a-8f34-51ec-4a7f66a87b39@linux.intel.com> (raw)
In-Reply-To: <YTiM/zf8BuNw7wes@hirez.programming.kicks-ass.net>
Op 08-09-2021 om 12:14 schreef Peter Zijlstra:
> On Tue, Sep 07, 2021 at 03:20:44PM +0200, Maarten Lankhorst wrote:
>> i915 will soon gain an eviction path that trylock a whole lot of locks
>> for eviction, getting dmesg failures like below:
>>
>> BUG: MAX_LOCK_DEPTH too low!
>> turning off the locking correctness validator.
>> depth: 48 max: 48!
>> 48 locks held by i915_selftest/5776:
>> #0: ffff888101a79240 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x88/0x160
>> #1: ffffc900009778c0 (reservation_ww_class_acquire){+.+.}-{0:0}, at: i915_vma_pin.constprop.63+0x39/0x1b0 [i915]
>> #2: ffff88800cf74de8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_vma_pin.constprop.63+0x5f/0x1b0 [i915]
>> #3: ffff88810c7f9e38 (&vm->mutex/1){+.+.}-{3:3}, at: i915_vma_pin_ww+0x1c4/0x9d0 [i915]
>> #4: ffff88810bad5768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
>> #5: ffff88810bad60e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
>> ...
>> #46: ffff88811964d768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
>> #47: ffff88811964e0e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
>> INFO: lockdep is turned off.
>> As an intermediate solution, add an acquire context to ww_mutex_trylock,
>> which allows us to do proper nesting annotations on the trylocks, making
>> the above lockdep splat disappear.
> Fair enough I suppose.
>
>> +/**
>> + * ww_mutex_trylock - tries to acquire the w/w mutex with optional acquire context
>> + * @lock: mutex to lock
>> + * @ctx: optional w/w acquire context
>> + *
>> + * Trylocks a mutex with the optional acquire context; no deadlock detection is
>> + * possible. Returns 1 if the mutex has been acquired successfully, 0 otherwise.
>> + *
>> + * Unlike ww_mutex_lock, no deadlock handling is performed. However, if a @ctx is
>> + * specified, -EALREADY and -EDEADLK handling may happen in calls to ww_mutex_lock.
>> + *
>> + * A mutex acquired with this function must be released with ww_mutex_unlock.
>> + */
>> +int __sched
>> +ww_mutex_trylock(struct ww_mutex *ww, struct ww_acquire_ctx *ctx)
>> +{
>> + bool locked;
>> +
>> + if (!ctx)
>> + return mutex_trylock(&ww->base);
>> +
>> +#ifdef CONFIG_DEBUG_MUTEXES
>> + DEBUG_LOCKS_WARN_ON(ww->base.magic != &ww->base);
>> +#endif
>> +
>> + preempt_disable();
>> + locked = __mutex_trylock(&ww->base);
>> +
>> + if (locked) {
>> + ww_mutex_set_context_fastpath(ww, ctx);
>> + mutex_acquire_nest(&ww->base.dep_map, 0, 1, &ctx->dep_map, _RET_IP_);
>> + }
>> + preempt_enable();
>> +
>> + return locked;
>> +}
>> +EXPORT_SYMBOL(ww_mutex_trylock);
> You'll need a similar hunk in ww_rt_mutex.c
What tree has that file?
next prev parent reply other threads:[~2021-09-09 5:38 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-07 13:20 [PATCH] kernel/locking: Add context to ww_mutex_trylock Maarten Lankhorst
2021-09-08 10:14 ` Peter Zijlstra
2021-09-08 18:30 ` Daniel Vetter
2021-09-09 5:38 ` Maarten Lankhorst [this message]
2021-09-09 8:22 ` Peter Zijlstra
2021-09-09 9:32 ` [PATCH v2] " Maarten Lankhorst
2021-09-10 15:02 ` Peter Zijlstra
2021-09-10 17:27 ` Peter Zijlstra
2021-09-13 8:42 ` Maarten Lankhorst
2021-09-14 6:50 ` Peter Zijlstra
2021-09-14 12:43 ` Maarten Lankhorst
2021-09-14 13:54 ` Daniel Vetter
2021-09-16 13:00 ` Maarten Lankhorst
2021-09-16 13:28 ` Peter Zijlstra
2021-09-17 13:13 ` Peter Zijlstra
2021-09-20 15:02 ` Joonas Lahtinen
2021-09-17 13:17 ` [tip: locking/core] kernel/locking: Add context to ww_mutex_trylock() tip-bot2 for Maarten Lankhorst
2021-11-04 12:27 ` [PATCH] kernel/locking: Use a pointer in ww_mutex_trylock() Sebastian Andrzej Siewior
2021-11-17 13:59 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-09-10 18:06 ` [PATCH v2] kernel/locking: Add context to ww_mutex_trylock Mark Brown
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=96ab9cf1-250a-8f34-51ec-4a7f66a87b39@linux.intel.com \
--to=maarten.lankhorst@linux.intel.com \
--cc=boqun.feng@gmail.com \
--cc=broonie@kernel.org \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=lgirdwood@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=longman@redhat.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=will@kernel.org \
/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 NNTP newsgroup(s).