Date: Wed, 4 May 2016 18:31:08 -0500 From: "Eric A. Borisch" <eborisch@gmail.com> To: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Notes on slow kernel/ZFS memory leak resolved with FreeBSD-EN-16:08.zfs Message-ID: <CAASnNnqeQ7hhGe2bH3nQOeU6J2_%2BEHD-aTU50V1MoUc1Ld-JkA@mail.gmail.com>
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To elaborate on EN-16:08: this fixes a bug where any attempt to access a (1) previously mounted and (2) now destroyed snapshot leads to a small kernel memory leak on each attempt. These attempts can come in via NFS, from a local (potentially non-privileged) user, or even from within a jail, so long as the user/service would be able to enter into valid snapshots -- they don't need to be able to create snapshots themselves. We noticed it from repeated NFS attempts to mount an expired rolling snapshot; due to a slow but steady retry, the leak was clearly visible over long (multi-week) timescales. The leaked memory will show up labeled as 'mount' in vmstat -m, and is easy to verify as it will steadily grow with each failed attempt. - Eric - Eric
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