From: Andrea Parri <andrea.parri@amarulasolutions.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: zhe.he@windriver.com, catalin.marinas@arm.com,
tglx@linutronix.de, rostedt@goodmis.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
boqun.feng@gmail.com
Subject: Re: [PATCH v2] kmemleak: Turn kmemleak_lock to raw spinlock on RT
Date: Fri, 23 Nov 2018 12:02:55 +0100 [thread overview]
Message-ID: <20181123110226.GA5125@andrea> (raw)
In-Reply-To: <20181123095314.hervxkxtqoixovro@linutronix.de>
> is this an RT-only problem? Because mainline should not allow read->read
> locking or read->write locking for reader-writer locks. If this only
> happens on v4.18 and not on v4.19 then something must have fixed it.
Probably misunderstanding, but I'd say that read->read locking is "the
norm"...?
If you don't use qrwlock, readers are also "recursive", in part.,
P0 P1
read_lock(l)
write_lock(l)
read_lock(l)
won't block P0 on the second read_lock(). (qrwlock somehow complicate
the analysis; IIUC, they are recursive if and only if in_interrupt().).
Andrea
>
>
> Sebastian
next prev parent reply other threads:[~2018-11-23 11:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 9:04 [PATCH v2] kmemleak: Turn kmemleak_lock to raw spinlock on RT zhe.he
2018-11-22 10:16 ` Sebastian Andrzej Siewior
2018-11-23 9:53 ` Sebastian Andrzej Siewior
2018-11-23 11:02 ` Andrea Parri [this message]
2018-11-23 11:06 ` Sebastian Andrzej Siewior
2018-11-23 11:31 ` Catalin Marinas
2018-11-23 15:51 ` Steven Rostedt
2018-11-26 8:40 ` Peter Zijlstra
2018-11-24 14:26 ` He Zhe
2018-11-30 18:19 ` Sebastian Andrzej Siewior
2018-12-05 13:53 ` He Zhe
2018-12-05 19:14 ` Sebastian Andrzej Siewior
2018-12-18 10:51 ` He Zhe
2018-12-18 15:07 ` Catalin Marinas
2018-12-19 15:30 ` Sebastian Andrzej Siewior
2018-12-20 1:46 ` He Zhe
2018-12-18 15:12 ` Catalin Marinas
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