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Sat, 14 Jan 2023 06:51:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 2B7kKAVRwmMlOwAAMHmgww (envelope-from ); Sat, 14 Jan 2023 06:51:49 +0000 Message-ID: <3e419e8e-cdd7-eaf5-0572-ae5c44d7b68e@suse.cz> Date: Sat, 14 Jan 2023 07:49:59 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH for 6.1 regression] Revert "mm/compaction: fix set skip in fast_find_migrateblock" Content-Language: en-US To: Andrew Morton Cc: patches@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, regressions@leemhuis.info, Jiri Slaby , Maxim Levitsky , Mel Gorman , Michal Hocko , Pedro Falcato , Paolo Bonzini , Chuyi Zhou , stable@vger.kernel.org References: <20230113173345.9692-1-vbabka@suse.cz> From: Vlastimil Babka In-Reply-To: <20230113173345.9692-1-vbabka@suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AFA421A0007 X-Stat-Signature: iibjoje6g8kxqis3sqtyfwm6th8cdggs X-HE-Tag: 1673679111-232614 X-HE-Meta: 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 oaG8I4WD HJ6mC3NPwmazlJC3L4ODW0eMkd+BPUJScJMkj3huFc6ypQ2KlFL2lvw/eVA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/13/23 18:33, Vlastimil Babka wrote: > This reverts commit 7efc3b7261030da79001c00d92bc3392fd6c664c. > > We have got openSUSE reports (Link 1) for 6.1 kernel with khugepaged > stalling CPU for long periods of time. Investigation of tracepoint data > shows that compaction is stuck in repeating fast_find_migrateblock() > based migrate page isolation, and then fails to migrate all isolated > pages. Commit 7efc3b726103 ("mm/compaction: fix set skip in > fast_find_migrateblock") was suspected as it was merged in 6.1 and in > theory can indeed remove a termination condition for > fast_find_migrateblock() under certain conditions, as it removes a place > that always marks a scanned pageblock from being re-scanned. There are > other such places, but those can be skipped under certain conditions, > which seems to match the tracepoint data. > > Testing of revert also appears to have resolved the issue, thus revert > the commit until a more robust solution for the original problem is > developed. > > It's also likely this will fix qemu stalls with 6.1 kernel reported in > Link 2, but that is not yet confirmed. > > Link: https://bugzilla.suse.com/show_bug.cgi?id=1206848 > Link: https://lore.kernel.org/kvm/b8017e09-f336-3035-8344-c549086c2340@kernel.org/ > Fixes: 7efc3b726103 ("mm/compaction: fix set skip in fast_find_migrateblock") > Cc: Oops, forgot: Signed-off-by: Vlastimil Babka > --- > mm/compaction.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/compaction.c b/mm/compaction.c > index ca1603524bbe..8238e83385a7 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1839,6 +1839,7 @@ static unsigned long fast_find_migrateblock(struct compact_control *cc) > pfn = cc->zone->zone_start_pfn; > cc->fast_search_fail = 0; > found_block = true; > + set_pageblock_skip(freepage); > break; > } > }