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From: Michal Hocko <mhocko@kernel.org>
To: Qian Cai <cai@lca.pw>
Cc: linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [RFC PATCH] mm: silence soft lockups from unlock_page
Date: Tue, 21 Jul 2020 14:17:52 +0200	[thread overview]
Message-ID: <20200721121752.GK4061@dhcp22.suse.cz> (raw)
In-Reply-To: <664A07B6-DBCD-4520-84F1-241A4E7A339F@lca.pw>

On Tue 21-07-20 07:44:07, Qian Cai wrote:
> 
> 
> > On Jul 21, 2020, at 7:25 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > 
> > Are these really important? I believe I can dig that out from the bug
> > report but I didn't really consider that important enough.
> 
> Please dig them out. We have also been running those things on
> “large” powerpc as well and never saw such soft-lockups. Those
> details may give us some clues about the actual problem.

I strongly suspect this is not really relevant but just FYI this is
16Node, 11.9TB with 1536CPUs system.

> Once we
> understand the problem better, we may judge if this “hack” is
> really worth it.

I do not have access to the machine so I can only judge from the boot
log I have in hands. And from that it is pretty clear that 
$ grep BUG tmp/attachment.txt | wc -l
896

$ grep BUG tmp/attachment.txt | grep "\[systemd" | wc -l
860

$ grep do_fault+0x448 tmp/attachment.txt | wc -l
860

that the boot struggles, lockups happen from udev workers and most of
them are stuck at the very same place which is unlock_page. The rest is
a part of the changelog.
-- 
Michal Hocko
SUSE Labs


  parent reply	other threads:[~2020-07-21 12:18 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-21  6:32 [RFC PATCH] mm: silence soft lockups from unlock_page Michal Hocko
     [not found] ` <FCC3EB2D-9F11-4E9E-88F4-40B2926B35CC@lca.pw>
2020-07-21 11:25   ` Michal Hocko
     [not found]     ` <664A07B6-DBCD-4520-84F1-241A4E7A339F@lca.pw>
2020-07-21 12:17       ` Michal Hocko [this message]
     [not found]         ` <20200721132343.GA4261@lca.pw>
2020-07-21 13:38           ` Michal Hocko
2020-07-21 14:17 ` Chris Down
2020-07-21 15:00   ` Michal Hocko
2020-07-21 15:33 ` Linus Torvalds
2020-07-21 15:49   ` Michal Hocko
2020-07-22 18:29   ` Linus Torvalds
2020-07-22 21:29     ` Hugh Dickins
2020-07-22 22:10       ` Linus Torvalds
2020-07-22 23:42         ` Linus Torvalds
2020-07-23  0:23           ` Linus Torvalds
2020-07-23 12:47           ` Oleg Nesterov
2020-07-23 17:32             ` Linus Torvalds
2020-07-23 18:01               ` Oleg Nesterov
2020-07-23 18:22                 ` Linus Torvalds
2020-07-23 19:03                   ` Linus Torvalds
2020-07-24 14:45                     ` Oleg Nesterov
2020-07-23 20:03               ` Linus Torvalds
2020-07-23 23:11                 ` Hugh Dickins
2020-07-23 23:43                   ` Linus Torvalds
2020-07-24  0:07                     ` Hugh Dickins
2020-07-24  0:46                       ` Linus Torvalds
2020-07-24  3:45                         ` Hugh Dickins
2020-07-24 15:24                     ` Oleg Nesterov
2020-07-24 17:32                       ` Linus Torvalds
2020-07-24 23:25                         ` Linus Torvalds
2020-07-25  2:08                           ` Hugh Dickins
2020-07-25  2:46                             ` Linus Torvalds
2020-07-25 10:14                           ` Oleg Nesterov
2020-07-25 18:48                             ` Linus Torvalds
2020-07-25 19:27                               ` Oleg Nesterov
2020-07-25 19:51                                 ` Linus Torvalds
2020-07-26 13:57                                   ` Oleg Nesterov
2020-07-25 21:19                               ` Hugh Dickins
2020-07-26  4:22                                 ` Hugh Dickins
2020-07-26 20:30                                   ` Hugh Dickins
2020-07-26 20:41                                     ` Linus Torvalds
2020-07-26 22:09                                       ` Hugh Dickins
2020-07-27 19:35                                     ` Greg KH
2020-08-06  5:46                                       ` Hugh Dickins
2020-08-18 13:50                                         ` Greg KH
2020-08-06  5:21                                     ` Hugh Dickins
2020-08-06 17:07                                       ` Linus Torvalds
2020-08-06 18:00                                         ` Matthew Wilcox
2020-08-06 18:32                                           ` Linus Torvalds
2020-08-07 18:41                                             ` Hugh Dickins
2020-08-07 19:07                                               ` Linus Torvalds
2020-08-07 19:35                                               ` Matthew Wilcox
2020-08-03 13:14                           ` Michal Hocko
2020-08-03 17:56                             ` Linus Torvalds
2020-07-25  9:39                         ` Oleg Nesterov
2020-07-23  8:03     ` Michal Hocko

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