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[37.188.169.187]) by smtp.gmail.com with ESMTPSA id c17sm23700986wrc.42.2020.07.21.05.17.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jul 2020 05:17:53 -0700 (PDT) Date: Tue, 21 Jul 2020 14:17:52 +0200 From: Michal Hocko To: Qian Cai Cc: linux-mm@kvack.org, LKML , Andrew Morton , Linus Torvalds , Tim Chen Subject: Re: [RFC PATCH] mm: silence soft lockups from unlock_page Message-ID: <20200721121752.GK4061@dhcp22.suse.cz> References: <20200721112529.GJ4061@dhcp22.suse.cz> <664A07B6-DBCD-4520-84F1-241A4E7A339F@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <664A07B6-DBCD-4520-84F1-241A4E7A339F@lca.pw> X-Rspamd-Queue-Id: 7049FE0A4E65 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000253, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 21-07-20 07:44:07, Qian Cai wrote: >=20 >=20 > > On Jul 21, 2020, at 7:25 AM, Michal Hocko wrote: > >=20 > > Are these really important? I believe I can dig that out from the bug > > report but I didn't really consider that important enough. >=20 > Please dig them out. We have also been running those things on > =E2=80=9Clarge=E2=80=9D 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 =E2=80=9Chack=E2=80= =9D 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=20 $ 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. --=20 Michal Hocko SUSE Labs