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Tue, 27 Oct 2026 05:16:50 -0700 (PDT) Received: from spartian.home ([2a01:cb1c:76:ed00:602f:c5f4:d108:b925]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e412cc164sm21108892f8f.7.2026.10.27.05.16.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 05:16:50 -0700 (PDT) From: Aurelien DESBRIERES To: jack@suse.cz Cc: brauner@kernel.org, willy@infradead.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com, aurelien.desbrieres@gmail.com Subject: Re: [syzbot ci] Re: buffer: warn when a buffer is attached to a second mmb Date: Tue, 27 Oct 2026 13:16:49 +0100 Message-ID: <20261027121649.69819-1-aurelien@hackers.camp> X-Mailer: git-send-email 2.55.0 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue 27-10-26 13:10:55, Jan Kara wrote: > Woohoo, great that we have added this. So now we have some filesystem bugs > to analyze ;). At least in ext4 case this is a real bug as xattr blocks can > be indeed shared among inodes. [...] > I'm not sure about the FAT cases because directory blocks where this > triggers should better belong to a single directory. So it could be some > race with freeing & reallocating blocks. Needs more digging. Our mails crossed; forget the pr_warn alternative then, the WARN stays as sent. If digging into the FAT cases from the syzbot repros helps, I can take that on; say so and I will report what I find. Your free and reallocate theory also describes something beamfs could do with its indirect blocks, so I am running xfstests against the warning on our side first. Aurelien