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Wed, 23 Oct 2024 20:13:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id N03pANtYGWexeAAAD6G6ig (envelope-from ); Wed, 23 Oct 2024 20:13:15 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id A301FA08A2; Wed, 23 Oct 2024 22:13:14 +0200 (CEST) Date: Wed, 23 Oct 2024 22:13:14 +0200 From: Jan Kara To: John Garry Cc: linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org Subject: Re: v6.12-rc workqueue lockups Message-ID: <20241023201314.hqfewgr6lej6f7df@quack3> References: <63d6ceeb-a22f-4dee-bc9d-8687ce4c7355@oracle.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <63d6ceeb-a22f-4dee-bc9d-8687ce4c7355@oracle.com> X-Rspamd-Queue-Id: 0F4C31F444 X-Spam-Level: X-Spamd-Result: default: False [-4.01 / 50.00]; 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On Wed 23-10-24 11:19:24, John Garry wrote: > I have been seeing lockups reliably occur on v6.12-rc1, 3, 4 and linus' > master branch: > > Message from syslogd@jgarry-atomic-write-exp-e4-8-instance-20231214-1221 at > Oct 22 09:07:15 ... > kernel:watchdog: BUG: soft lockup - CPU#12 stuck for 26s! [khugepaged:154] > > Message from syslogd@jgarry-atomic-write-exp-e4-8-instance-20231214-1221 at > Oct 22 09:08:07 ... > kernel:BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck > for 44s! > > Message from syslogd@jgarry-atomic-write-exp-e4-8-instance-20231214-1221 at > Oct 22 09:08:07 ... > kernel:BUG: workqueue lockup - pool cpus=4 node=0 flags=0x0 nice=0 stuck > for 35s! > > Message from syslogd@jgarry-atomic-write-exp-e4-8-instance-20231214-1221 at > Oct 22 09:08:07 ... > kernel:BUG: workqueue lockup - pool cpus=10 node=0 flags=0x0 nice=0 stuck > for 33s! > > This is while doing some server MySQL performance testing. v6.11 has no such > issue. > > I added some debug, and we seem to be spending a lot of time in FS > writeback, specifically wb_workfn() -> wb_do_writeback() - ring any bells? Thanks for report. This doesn't remind me of anything but checking the writeback changes we have merged 532980cb1bf ("inode: port __I_SYNC to var event") which could have odd consequences if we made mistake somewhere... It probably won't be easy to revert but you could try whether the problem reproduces before / after this commit. Honza -- Jan Kara SUSE Labs, CR