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From: "Luck, Tony" <tony.luck@intel.com>
To: Borislav Petkov <bp@alien8.de>, Andi Kleen <ak@linux.intel.com>
Cc: Jeremy Cline <jcline@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Laura Abbott <labbott@redhat.com>
Subject: RE: x86/mce: suspicious RCU usage in 4.13.4
Date: Wed, 11 Oct 2017 21:34:22 +0000	[thread overview]
Message-ID: <3908561D78D1C84285E8C5FCA982C28F770038E5@ORSMSX114.amr.corp.intel.com> (raw)
In-Reply-To: <20171011115020.i4gkcy5pjifh2zsm@pd.tnic>

> here's a second attempt at a more rigorous simplification: RCU stuff is
> gone and only a single loop scans through the elements.

The dev_mce_log() changes look good now.

You can apply the axe to more bits of mce_chrdev_read() though. Like that

	while (!m->finished) {

we hold the mutex, the writer of that holds the mutex ... the spin loop is going to always
time out.  

-Tony

WARNING: multiple messages have this Message-ID (diff)
From: "Luck, Tony" <tony.luck@intel.com>
To: Borislav Petkov <bp@alien8.de>, Andi Kleen <ak@linux.intel.com>
Cc: Jeremy Cline <jcline@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Laura Abbott <labbott@redhat.com>
Subject: x86/mce: suspicious RCU usage in 4.13.4
Date: Wed, 11 Oct 2017 21:34:22 +0000	[thread overview]
Message-ID: <3908561D78D1C84285E8C5FCA982C28F770038E5@ORSMSX114.amr.corp.intel.com> (raw)

> here's a second attempt at a more rigorous simplification: RCU stuff is
> gone and only a single loop scans through the elements.

The dev_mce_log() changes look good now.

You can apply the axe to more bits of mce_chrdev_read() though. Like that

	while (!m->finished) {

we hold the mutex, the writer of that holds the mutex ... the spin loop is going to always
time out.  

-Tony

  reply	other threads:[~2017-10-11 21:34 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-10 19:00 x86/mce: suspicious RCU usage in 4.13.4 Jeremy Cline
2017-10-10 19:44 ` Borislav Petkov
2017-10-10 19:44   ` Borislav Petkov
2017-10-10 20:08   ` Luck, Tony
2017-10-10 20:08     ` Luck, Tony
2017-10-10 20:13     ` Andi Kleen
2017-10-10 20:13       ` Andi Kleen
2017-10-11 11:50       ` Borislav Petkov
2017-10-11 11:50         ` Borislav Petkov
2017-10-11 21:34         ` Luck, Tony [this message]
2017-10-11 21:34           ` Luck, Tony
2017-10-15  9:40           ` Borislav Petkov
2017-10-15  9:40             ` Borislav Petkov
2017-10-16 18:28             ` Luck, Tony
2017-10-16 18:28               ` Luck, Tony
2017-11-01 14:56               ` Laura Abbott
2017-11-01 14:56                 ` Laura Abbott
2017-11-01 16:47                 ` Borislav Petkov
2017-11-01 16:47                   ` Borislav Petkov
2017-11-01 20:07                   ` Luck, Tony
2017-11-01 20:07                     ` Luck, Tony
2017-11-01 20:28                   ` [tip:ras/urgent] x86/mcelog: Get rid of RCU remnants tip-bot for Borislav Petkov
2017-10-11 23:11         ` x86/mce: suspicious RCU usage in 4.13.4 Andi Kleen
2017-10-11 23:11           ` Andi Kleen
2017-10-12  9:02           ` Borislav Petkov
2017-10-12  9:02             ` Borislav Petkov
2017-10-12 22:13             ` Andi Kleen
2017-10-12 22:13               ` Andi Kleen

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