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Received: from viro by zeniv.linux.org.uk with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1vlzd9-0000000DGbm-14ID; Sat, 31 Jan 2026 01:18:31 +0000 Date: Sat, 31 Jan 2026 01:18:31 +0000 From: Al Viro To: Samuel Wu Cc: Greg KH , linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org, brauner@kernel.org, jack@suse.cz, raven@themaw.net, miklos@szeredi.hu, neil@brown.name, a.hindborg@kernel.org, linux-mm@kvack.org, linux-efi@vger.kernel.org, ocfs2-devel@lists.linux.dev, kees@kernel.org, rostedt@goodmis.org, linux-usb@vger.kernel.org, paul@paul-moore.com, casey@schaufler-ca.com, linuxppc-dev@lists.ozlabs.org, john.johansen@canonical.com, selinux@vger.kernel.org, borntraeger@linux.ibm.com, bpf@vger.kernel.org, clm@meta.com, android-kernel-team Subject: Re: [PATCH v4 00/54] tree-in-dcache stuff Message-ID: <20260131011831.GZ3183987@ZenIV> References: <20260128045954.GS3183987@ZenIV> <20260129032335.GT3183987@ZenIV> <20260129225433.GU3183987@ZenIV> <20260130070424.GV3183987@ZenIV> <20260130235743.GW3183987@ZenIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Stat-Signature: ntzfabfyg8bmt7zkuwy4jhn5bbnfuhe5 X-Rspamd-Queue-Id: 3245914000B X-Rspam-User: X-HE-Tag: 1769822202-565465 X-HE-Meta: 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 kxbvQ5sB Z+1vEvE0mz2XAghSogpxyAezGy4LiO+Ge3Jui33bVh71HtYGWpV/3DMDYgsZi059T5A8JuwrzNO8sTFNDWqW42sJt+c66sYFjZv4QAxEWNvmbQjDHN8d4AP3pT0+ZTZF4JSFu3GOvQsZ6xSlGZKZ7ys1BUY6I92pL9INV6Mk0Z0liWyf00ik+hg6IvkW1/6hohmYW+YhioVLfUhzydooD/xl4S+BmYjXx4Zzqitf6LAjIGmJqxhLv6jCytHnple+CfcdBAvXeYX3fm9DZBTMgYlO7Ejd5OHKMvnKFo/41KLWKkqgv0z+xTdBfPraH6erkzpoMw7fqpbCrKsfbQsjNIdAtpuAUiyULobguDsTNWmm2CHFFpFcZot/bw0XGWJ/FuAKcw+oA7RU3dT9UKJ2JqBY0W3JqbaYVbY491VPNpl8gvLQB/WH/VvTLGbFKE68nMOHt7q8kKTem4S1uOUWwrDAKHA== 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 Fri, Jan 30, 2026 at 05:05:34PM -0800, Samuel Wu wrote: > > How lovely... Could you slap > > WARN_ON(ret == -EAGAIN); > > right before that > > if (ret < 0) > > return ret; > > Surprisingly ret == 0 every time, so no difference in dmesg logs with > this addition. What the hell? Other than that mutex_lock(), the only change in there is the order of store to file->private_data and call of ffs_data_opened(); that struct file pointer is not visible to anyone at that point... Wait, it also brings ffs_data_reset() on that transition under ffs->mutex... For a quick check: does git fetch git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git for-wsamuel2 git switch --detach FETCH_HEAD demonstrate the same breakage?