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Thu, 8 Aug 2024 10:21:04 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Thu, 08 Aug 2024 16:20:43 +0200 From: "Morten Hein Tiljeset" To: "Christian Brauner" Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: In-Reply-To: <20240808-hangar-jobverlust-2235f6ef0ccb@brauner> References: <22578d44-b822-40ff-87fb-e50b961fab15@app.fastmail.com> <20240808-hangar-jobverlust-2235f6ef0ccb@brauner> Subject: Re: Debugging stuck mount Content-Type: text/plain Content-Transfer-Encoding: 7bit > It's likely held alive by some random file descriptor someone has open. > IOW, try and walk all /proc//fd/ in that case and see whether > anything keeps it alive. Thanks for the suggestion, but I've already tried the equivalent of that by using a debugger to find the superblock in question and then walking all open fds and comparing the superblock pointer. I've validated that this approach works in a synthetic example where I create a new namespace, mount the filesystem under /mnt, run a program to open /mnt/foo and lazy unmount /mnt. Walking procfs seems less precise. I've tried iterating through /proc/*/fd/* and comparing the Device entry of stat -L, also without luck.