From owner-freebsd-fs@freebsd.org Wed May 4 23:31:09 2016 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DD59BB2D683 for ; Wed, 4 May 2016 23:31:09 +0000 (UTC) (envelope-from eborisch@gmail.com) Received: from mail-ob0-x242.google.com (mail-ob0-x242.google.com [IPv6:2607:f8b0:4003:c01::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id A58B31BCD for ; Wed, 4 May 2016 23:31:09 +0000 (UTC) (envelope-from eborisch@gmail.com) Received: by mail-ob0-x242.google.com with SMTP id ds10so3862734obb.3 for ; Wed, 04 May 2016 16:31:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to; bh=BPI/FivDrao+Dlm3aNzPH7o0sR6wlV73wEru/if5MGs=; b=TFeA3KvkilGJ13VO5Ytoy597pGufZYHLnqCkHZ03NmU6OrGOmygtdVwU3x4SBKfej4 j9+g4E2vMhfnxfBKL0HxdD8qAYOsSinSlE7bTgonCIaN7b2m86tL6mnFEqRO4ib8mQU/ LxSe+eNSvWaqOOxiFlmrFCtuZxGh1q2rYGWMi4vWdPLLUImUJK+KkGu1cLflCsCMfUif FleVqesCicS95k4FRMfvHamshevK4awoIeZ0st1Vis1Mmk5D1FQcDKIck+5kPdyoeP4R MeOKr0mDg+x0fdt0B90rVwXYjst8T3ghs3IyvDv/LKlZCrYFVKy1tTvTE+5sQ1GeQEKn SdVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=BPI/FivDrao+Dlm3aNzPH7o0sR6wlV73wEru/if5MGs=; b=gAgvNRGuUVA8cHJPe974HxGePRQwKz+5wBoQKIqeFS8JWVHXCUQzXPFOttBDX0nCtY kJvHfK4nmw/ZW+TzoW7qQafgK/oD4/LmWcFiU43v9iiRNpqGQJiCkfvfoxDX0T2/ntip amhuxOmiEMrhR9zcIdNEi/iBzHoSap2z+G+lIiYbpEzvypoWIQ8I98SzA6M1vCBXEJDP +Q/SHiK7EsQ6Eo/Y521mgJDMA2vkptki3985BA0eLJQRJa6M/bgmZZCM1Thx9giaXMAM 6Dku00I24ztQOcoubJNfEZOYa3kQPnmSIA1ulQCw5XxYaNJVnNjFmVUyWumKq4yz1hEW tPjA== X-Gm-Message-State: AOPr4FWJN0OzCSv36YU8IwBPVmoFI3XWBXLv7TTaKl8pokFR5xRkaYpLQ8obUdaSeK/aFMW/vzfDMsDXpCVYBA== MIME-Version: 1.0 X-Received: by 10.182.233.163 with SMTP id tx3mr5498594obc.36.1462404669042; Wed, 04 May 2016 16:31:09 -0700 (PDT) Received: by 10.60.52.145 with HTTP; Wed, 4 May 2016 16:31:08 -0700 (PDT) Date: Wed, 4 May 2016 18:31:08 -0500 Message-ID: Subject: Notes on slow kernel/ZFS memory leak resolved with FreeBSD-EN-16:08.zfs From: "Eric A. Borisch" To: "freebsd-fs@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.22 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 May 2016 23:31:10 -0000 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