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From: Catalin Marinas <catalin.marinas@arm.com>
To: Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc: Robin Murphy <robin.murphy@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Oscar Salvador <osalvador@suse.de>,
	Wei Yang <richard.weiyang@gmail.com>,
	Michal Hocko <mhocko@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Sri Krishna chowdary <schowdary@nvidia.com>,
	Qian Cai <cai@lca.pw>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: kmemleak panic
Date: Sat, 19 Jan 2019 13:28:33 +0000	[thread overview]
Message-ID: <20190119132832.GA29881@MBP.local> (raw)
In-Reply-To: <b7629ecf-757c-f8b5-df83-ba83d7036b2f@free.fr>

On Fri, Jan 18, 2019 at 04:36:59PM +0100, Marc Gonzalez wrote:
> mount -t debugfs nodev /sys/kernel/debug/ 
> echo scan > /sys/kernel/debug/kmemleak
> 
> Unable to handle kernel paging request at virtual address ffffffc021e00000
[...]
> Call trace:
>  scan_block+0x70/0x190
>  scan_gray_list+0x108/0x1c0
>  kmemleak_scan+0x33c/0x7c0
>  kmemleak_write+0x410/0x4b0

As per Robin's remark, this address seems to be pretty easy to
reproduce. It also happens via scan_gray_list() which indicates an
object kmemleak was informed about via kmemleak_alloc() (so this
excludes the pfn that Qian noticed).

Can you configure the kernel with CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN off
just to avoid the bug being triggered early and run:

  mount -t debugfs nodev /sys/kernel/debug/
  echo dump=0xffffffc021e00000 > /sys/kernel/debug/kmemleak

Then run another scan to make sure this is the address that triggered
the page fault:

  echo scan > /sys/kernel/debug/kmemleak

The above should tell us where the object that kmemleak is trying to
scan came from.

Of course, ideally we should bisect this but I haven't been able to
reproduce it.

-- 
Catalin

  parent reply	other threads:[~2019-01-19 13:28 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <f6fbf528-8213-e3b8-6990-9fcf9dec04d6@free.fr>
     [not found] ` <20190118143434.GE118707@arrakis.emea.arm.com>
2019-01-18 15:36   ` kmemleak panic Marc Gonzalez
2019-01-18 16:14     ` Qian Cai
2019-01-18 17:05       ` Marc Gonzalez
2019-01-18 17:38         ` Qian Cai
2019-01-19 10:21           ` Marc Gonzalez
2019-01-18 19:12     ` Robin Murphy
2019-01-19 13:28     ` Catalin Marinas [this message]
2019-01-21 11:57       ` Marc Gonzalez
2019-01-21 12:19         ` Robin Murphy
2019-01-21 13:35           ` Rob Herring
2019-01-21 13:54             ` Marc Gonzalez
2019-01-22  8:20               ` Prateek Patel
2019-01-21 14:37             ` Catalin Marinas
2019-01-21 15:42               ` Rob Herring
2019-01-21 15:53                 ` Robin Murphy
2019-01-21 17:42                 ` Mike Rapoport
2019-01-22 14:02                   ` Marc Gonzalez
2019-01-22 14:12                     ` Marc Gonzalez
2019-01-23  5:54                       ` Mike Rapoport
2019-01-23  7:05                         ` Prateek Patel
2019-01-23  7:28                         ` Marek Szyprowski
2019-01-23 12:31                           ` [PATCH v2] of: fix kmemleak crash (was: Re: kmemleak panic) Mike Rapoport
2019-02-01 16:23                             ` [PATCH v2] of: fix kmemleak crash Marc Gonzalez
2019-02-04 10:10                               ` Marc Gonzalez
2019-02-04 15:25                                 ` Greg Kroah-Hartman
2019-02-04 16:41                                   ` Rob Herring
2019-02-04 14:37                             ` [RESEND PATCH v2] of: fix kmemleak crash caused by imbalance in early memory reservation Marc Gonzalez
2019-02-11 16:47                               ` Marc Gonzalez
2019-02-12 16:03                                 ` Rob Herring
2019-02-12 21:50                                   ` Stephen Rothwell
2019-02-12 21:52                                     ` Andrew Morton
2019-02-12 22:12                                     ` Rob Herring
2019-02-13  6:57                                       ` Mike Rapoport
2019-02-13  9:27                                         ` Marc Gonzalez
2019-02-13 16:30                                           ` Mike Rapoport
2019-03-06  2:12                                       ` Guenter Roeck
2019-03-06 13:39                                         ` Rob Herring
2019-03-06 16:18                                           ` Guenter Roeck
2019-01-21 12:22         ` kmemleak panic Marc Gonzalez

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