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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id v27-20020a05620a123b00b0078eec8445dbsm854807qkj.47.2024.04.15.08.43.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Apr 2024 08:43:19 -0700 (PDT) Date: Mon, 15 Apr 2024 11:43:17 -0400 From: Peter Xu To: Andrew Morton Cc: syzbot , linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] WARNING in try_to_migrate_one (2) Message-ID: References: <0000000000001a87b90613389171@google.com> <000000000000dce0530615c89210@google.com> <20240411125513.b779991117a4dea92ce77269@linux-foundation.org> MIME-Version: 1.0 In-Reply-To: <20240411125513.b779991117a4dea92ce77269@linux-foundation.org> X-Mimecast-Spam-Score: 1 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Stat-Signature: saqznra9rtf7szn4pbun79darw1am81b X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 97491A000C X-HE-Tag: 1713195802-689572 X-HE-Meta: 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 gh+/GsgR 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 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: List-Subscribe: List-Unsubscribe: On Thu, Apr 11, 2024 at 12:55:13PM -0700, Andrew Morton wrote: > On Wed, 10 Apr 2024 19:04:21 -0700 syzbot wrote: > > > syzbot has found a reproducer for the following issue on: > > Thanks. > > > HEAD commit: 480e035fc4c7 Merge tag 'drm-next-2024-03-13' of https://gi.. > > git tree: upstream > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=14db82bd180000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=1e5b814e91787669 > > dashboard link: https://syzkaller.appspot.com/bug?extid=ddf4b4c0005944105a9e > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13111a4d180000 > > Seems to be userfaultfd related. > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=156ae155180000 I can't easily trigger with the reproducer, neither did I get more information from the syzbot reproducer, and it doesn't include an UFFDIO_REGISTER. Before go reading more on syzbot itself on this specific reproducer, I'll see whether I can come up with something better than commit c2da319c2e2: I don't remember the details why I didn't do the sanity check when updating the pgtable rather than walking it. I'll give it a shot this time. Thanks, -- Peter Xu