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Tue, 3 Mar 2026 16:18:59 +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 M8o0E/MJp2ldBQAAD6G6ig (envelope-from ); Tue, 03 Mar 2026 16:18:59 +0000 Date: Tue, 3 Mar 2026 17:18:43 +0100 From: David Sterba To: syzbot Cc: clm@fb.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [btrfs?] WARNING: suspicious RCU usage in btrfs_dev_stat_inc_and_print Message-ID: <20260303161843.GD8455@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <69a5f980.a70a0220.b118c.0004.GAE@google.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: <69a5f980.a70a0220.b118c.0004.GAE@google.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Spam-Score: -1.50 X-Spam-Level: X-Spamd-Result: default: False [-1.50 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; URI_HIDDEN_PATH(1.00)[https://syzkaller.appspot.com/x/.config?x=98a1e192f758c1c1]; HAS_REPLYTO(0.30)[dsterba@suse.cz]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; ARC_NA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:replyto]; REPLYTO_DOM_NEQ_TO_DOM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; REPLYTO_ADDR_EQ_FROM(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; RCVD_COUNT_TWO(0.00)[2]; TAGGED_RCPT(0.00)[2c45a55710ac9b888efc]; SUBJECT_HAS_QUESTION(0.00)[] X-Spam-Flag: NO On Mon, Mar 02, 2026 at 12:56:32PM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 7d6661873f6b Add linux-next specific files for 20260226 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1753c202580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=98a1e192f758c1c1 > dashboard link: https://syzkaller.appspot.com/bug?extid=2c45a55710ac9b888efc > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/4cd2824adb8a/disk-7d666187.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/bbdd4a130d86/vmlinux-7d666187.xz > kernel image: https://storage.googleapis.com/syzbot-assets/6e3bea3e96f8/bzImage-7d666187.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+2c45a55710ac9b888efc@syzkaller.appspotmail.com > > loop0: detected capacity change from 32768 to 0 > ============================= > WARNING: suspicious RCU usage > syzkaller #0 Not tainted > ----------------------------- > fs/btrfs/volumes.h:872 suspicious rcu_dereference_check() usage! #syz invalid Marking as invalid so it does not appear in the list of issues but otherwise it's a valid report caused by patch that has been removed. https://lore.kernel.org/linux-btrfs/20260205114546.210418-1-dsterba@suse.com/