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[209.85.220.65]) by mx.google.com with SMTPS id s25sor13307294iol.28.2019.04.25.13.45.54 for (Google Transport Security); Thu, 25 Apr 2019 13:45:54 -0700 (PDT) Received-SPF: pass (google.com: domain of matthewgarrett@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=MRWUNUxA; spf=pass (google.com: domain of matthewgarrett@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=matthewgarrett@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=fTCIXrMkQw8DWjirY0wbyKHBu3z39INvewV6V58xb34=; b=MRWUNUxAgMtfjEUKh5EiicK3Gw8p3WkCwK0DaRezcQPhpuLx8df5emcz4NTK4E5D1o gAu0JkwLC+9tUT8zbS9e51olKa2jyblmviizLkXanyqOnYG93fxu/gElGFUGcmWOp/OB IfKtowKQ+80dsUp4qfifBulhtVIsPHSkOGGHLmB3TAgUTCkCcfBTt3ncKeByczcklw+c 5YOVm2E0mHEqz+FQwKO+YAzhUkzxvF2dlEBEo0uyQ/CjOPgK7+JpfaFUw8R76QnHKmaX 8u7U2ZhFNXvy/CCqKWdoRxpJjYhvxFtD4Ta/5Ij26a4vTAxBONBuPgh04ErsTEKhI/JX uHSA== X-Google-Smtp-Source: APXvYqxXUTfVNIfA/fuKFQepO3/TNOnkhuDEVEZ0HByFbGB34orvrJ/gIzU17shHf9oBJnXNEcjKm3AfDav4RWXi5X0= X-Received: by 2002:a6b:e20e:: with SMTP id z14mr24868217ioc.169.1556225153517; Thu, 25 Apr 2019 13:45:53 -0700 (PDT) MIME-Version: 1.0 References: <20190424211038.204001-1-matthewgarrett@google.com> <20190425121410.GC1144@dhcp22.suse.cz> <1df0ef0c-4219-c259-18a2-9abfb2782c08@suse.cz> In-Reply-To: <1df0ef0c-4219-c259-18a2-9abfb2782c08@suse.cz> From: Matthew Garrett Date: Thu, 25 Apr 2019 13:45:42 -0700 Message-ID: Subject: Re: [PATCH V2] mm: Allow userland to request that the kernel clear memory on release To: Vlastimil Babka Cc: Michal Hocko , Linux-MM , Linux Kernel Mailing List , Linux API Content-Type: text/plain; charset="UTF-8" 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: On Thu, Apr 25, 2019 at 5:44 AM Vlastimil Babka wrote: > > On 4/25/19 2:14 PM, Michal Hocko wrote: > > Please cc linux-api for user visible API proposals (now done). Keep the > > rest of the email intact for reference. > > > > On Wed 24-04-19 14:10:39, Matthew Garrett wrote: > >> From: Matthew Garrett > >> > >> Applications that hold secrets and wish to avoid them leaking can use > >> mlock() to prevent the page from being pushed out to swap and > >> MADV_DONTDUMP to prevent it from being included in core dumps. Applications > > So, do we really need a new madvise() flag and VMA flag, or can we just > infer this page clearing from mlock+MADV_DONTDUMP being both applied? I think the combination would probably imply that this is the behaviour you want, but I'm a little concerned about changing the semantics given the corner cases described earlier in the thread. If we can figure those out in a way that won't break any existing code, I could buy this.