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From: Mike Galbraith <efault@gmx.de>
To: Vlastimil Babka <vbabka@suse.cz>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>
Cc: linux-rt-users@vger.kernel.org,
	Mel Gorman <mgorman@techsingularity.net>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [patch] v2 mm/slub: restore/expand unfreeze_partials() local exclusion scope
Date: Mon, 19 Jul 2021 06:01:38 +0200	[thread overview]
Message-ID: <00a7c04b109c01a7668abc2a8192a6b889765de5.camel@gmx.de> (raw)
In-Reply-To: <dd10ebb3-7687-6e8d-8984-3dfb9cd0e927@suse.cz>

(a pox on whomever broke evolution text quoting yet again)

On Sun, 2021-07-18 at 23:19 +0200, Vlastimil Babka wrote:
>
> Hm you mention put_cpu_partial() but your patch handles only the
> unfreeze_partial() call from that function?

Indeed, and that's because when I poked that slub_get_cpu_ptr(), it
poked me back by real deal deadlocking on boot, so I posted the
restoration of previously existing exclusion points with the
unlock/relock to appease lockdep (big hairy wart) bit instead.

>  If I understand the problem
> correctly, all modifications of cpu_slab->partial has to be protected
> on RT after the local_lock conversion, thus also the one that
> put_cpu_partial() does by itself (via this_cpu_cmpxchg).

Yup, that's what I concluded too, but box disagreed by not booting when
I did that, while seemingly being perfectly fine with the one in
put_cpu_partial() itself.  I figured my slub_get_cpu_ptr() replacement
had failed due to list_lock/local_lock order woes that I didn't notice
until after box bricked on me, but despite the unlock/relock in this
patch, it still manages to be a -ENOBOOT.

	-Mike


  reply	other threads:[~2021-07-19  4:01 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-08  9:42 [ANNOUNCE] v5.13-rt1 Thomas Gleixner
2021-07-09  5:20 ` [patch] mm/slub: Fix kmem_cache_alloc_bulk() error path Mike Galbraith
2021-07-09  5:20 ` [patch] mm/slub: Replace do_slab_free() local_lock_irqsave/restore() calls in PREEMPT_RT scope Mike Galbraith
2021-07-09  5:21 ` [rfc/patch] mm/slub: restore/expand unfreeze_partials() local exclusion scope Mike Galbraith
2021-07-09  5:25   ` Mike Galbraith
2021-07-09 19:28   ` Thomas Gleixner
2021-07-10  1:12     ` Mike Galbraith
2021-07-15 16:34       ` Mike Galbraith
2021-07-17 14:58         ` [patch] v2 " Mike Galbraith
2021-07-18  7:58           ` Vlastimil Babka
2021-07-18  8:11             ` Mike Galbraith
2021-07-18 15:43           ` Mike Galbraith
2021-07-18 21:19           ` Vlastimil Babka
2021-07-19  4:01             ` Mike Galbraith [this message]
2021-07-19 13:15               ` Mike Galbraith
2021-07-20  2:46           ` kernel test robot
2021-07-20  2:46             ` kernel test robot
2021-07-20  8:56         ` [rfc/patch] " Vlastimil Babka
2021-07-20 11:26           ` Mike Galbraith
2021-07-21  4:56             ` Mike Galbraith
2021-07-21  8:44               ` Vlastimil Babka
2021-07-21  9:33                 ` Mike Galbraith
2021-07-23 22:39                   ` Vlastimil Babka
2021-07-24  2:25                     ` Mike Galbraith
2021-07-25 14:09                     ` Mike Galbraith
2021-07-25 14:16                       ` Vlastimil Babka
2021-07-25 15:02                         ` Mike Galbraith
2021-07-25 16:27                           ` Vlastimil Babka
2021-07-25 19:12                             ` Vlastimil Babka
2021-07-25 19:34                               ` Vlastimil Babka
2021-07-26 10:04                                 ` Mike Galbraith
2021-07-26 17:00                                 ` Mike Galbraith
2021-07-26 21:26                                   ` Vlastimil Babka
2021-07-27  4:09                                     ` Mike Galbraith
2021-07-28 16:59                                       ` Vlastimil Babka
2021-07-29  4:51                                         ` Mike Galbraith
2021-07-29  9:51                                           ` Vlastimil Babka

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