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Fri, 30 Jan 2026 18:09:11 -0800 (PST) MIME-Version: 1.0 References: <20260128045954.GS3183987@ZenIV> <20260129032335.GT3183987@ZenIV> <20260129225433.GU3183987@ZenIV> <20260130070424.GV3183987@ZenIV> <20260130235743.GW3183987@ZenIV> <20260131011831.GZ3183987@ZenIV> In-Reply-To: <20260131011831.GZ3183987@ZenIV> From: Samuel Wu Date: Fri, 30 Jan 2026 18:09:00 -0800 X-Gm-Features: AZwV_QgpcNm32QTyYTJNZ2e8MpZD_azq4tiS_evKebHi_xWHPJAAyFUDpR04HdE Message-ID: Subject: Re: [PATCH v4 00/54] tree-in-dcache stuff To: Al Viro 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: ofm6eoeysw4btwnzj1y31u3ysnt3em4e X-Rspamd-Queue-Id: D26FF1C000B X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1769825353-941805 X-HE-Meta: U2FsdGVkX19wBnAVL/iwmKC8J6CPiso4otXqrIK50H8oW+HNJ3+3N6o/8MizddsRVUK7DUhAwt5Hm8BABuRUo3R6jvSCxaTNhBIBphYktktwCE/X8KMw5SKDbSuiujtlhc1ZtkF5kbkJZipOv3GMU+t4xB1lC7qGF9XZ8Ijy+977/OqGHxx91FtN1TD511I/4MIxju1FwdTbwQa+9a1ghiBExRKMPKSTR35X6YTxeyL5/yxxIiiKSOL07U4EaidHFlNL8xLk1OBJT/XYN7KLP9uTYk5SH9gmKFLYP7aXWZsbky+AfjS4NRMM0MF0qQhsRTJPgws/Nym8JoRbX3ARW662oLNeU5hoTg/x8FM21YtH672vlLxbKBzjuEPkUd52aZRCKhrcRxdXOHn6tPxSGWvZbJ1kpC7CChCU2BvHSzgeX+7XS+i3ZsqS25GlJmvdrZI2Ly3AotU2a5b6Fbh0wuPzfDVMo1TaKtB/GmyYJuXTLcRJW0nGSfX0avhvi3sEcsv4ObW7lw+I0Zt3BkjK41PcxQYFxdWHgBfV88nJ96dfIA/SsqZf72mtMZ8/mDl1FjGQRyfY2dBu+rLi+NXs1VF1KwT4TEQNC3MAv8buxJ+tHwGL5jKmiQxrSt849P6sqBYEI+GbSng3wRkT6zj8nzuK+HJwKzf2EHJTB8azr1X3YaGa97HWGpq0jnq8KkIxNttWTKa1Fr6sJMye+ZN7SCbyDJe35hbVhVPsVJcyFWRR/5cS9YavQngLlOSyT6yvApRdNfInebyKo8Ekd4NjG8bEuxoGWt50fZ+N1Zs0VDc1OCQwEYw0kyGn85BFACIsUySxKWzPecm+/OQ1FF+xc1fTKEp7G/3PxvhkceZEJQ5212eu52QF04XR5kzYf8dSdI0CM+h3mp6qm3W32kespmRLSMsNfqYVJMGL8Zo+GClutWSAvjTbywPai4PGtnvEqRDPQ0HCLC68iej9sUv 5s36ZCoG /iMJL2ayjq8ZQekYnrmp+kGXs66OGovT6B9EXWz1zvuowPIgV709PgoCQjR0eWeSRD5ZquyDkuOzOqG/e/ZtlI8FvoaxW4F1xAbtFZ11ZPYJCMT1hYu6qA9pGaLn25CjT/3L5ryqauPkHHAup643Bobj6UCqSfN9rF72zilVAyYoDwhLqDv3ITm0yJZ+uxfhFmb50xSlo4TWc93xysIg8YuWqBpWvG4Vem2NdgFxMsi3TAyWlfa4e9FaaEH5ptRvXx9TBrKAyTXTOgk1tKVrXa7vvT52DA2QhpkQtD3+VEgo8p7Le1jPpv5aetfhtyWQbJqjuFgG6QumA/Bq9u9ogzm25sqnSdDX0IQ6G3lVsXnVKSTwcyk38+vV5qqN85hvCiu0NZgRwjExvR65JaLThCSEL4w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000299, 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 5:16=E2=80=AFPM Al Viro w= rote: > > On Fri, Jan 30, 2026 at 05:05:34PM -0800, Samuel Wu wrote: > > > > How lovely... Could you slap > > > WARN_ON(ret =3D=3D -EAGAIN); > > > right before that > > > if (ret < 0) > > > return ret; > > > > Surprisingly ret =3D=3D 0 every time, so no difference in dmesg logs wi= th > > 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... Agree, 09e88dc22ea2 (serialize ffs_ep0_open() on ffs->mutex) in itself is quite straightforward. Not familiar with this code path so just speculating, but is there any interaction with previous patches (e.g. refcounting)? > 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? Had to adjust forward declaration of ffs_data_reset() to build, but unfortunately same breakage.