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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id s9si22922009pfa.282.2019.04.11.08.33.28 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 11 Apr 2019 08:33:28 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=OBiPuxAU; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=KCh9rGSq/KL+6mqDbYpIlhQVTAEOXp0DwEg9orG5vFk=; b=OBiPuxAUqmi4MzzMOAbfGUg3p OsRROYl/3oMT+lqMELNrjtTdjmaVU12ZIvPy1FUKd7IaQdx3001ZjQfUwxsPDbpEpQ4t3K1anfRwb mfeQVW5DYiApCBa1+F1q0ISj2o5jsPKF9RB5Qygpqo9r2RefUae3Vg7XKslgaIrXSDE4oF9unbEwM 61iSdWXRcAqbiynMfNqpz99f+OKBTkQruOitwbYhW77q3qFUfMCl1G4UNlsI5GFmcKgYQhr7UKH+Q 0CUUcg3x87CVAUNx3f6AE58umR0TooNMRd/ErVEm+IV/gev4UEn3czJF2NE7Kv61qYZrM1Bkcmzqj niIdh0kKw==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hEbhR-0004hT-HN; Thu, 11 Apr 2019 15:33:13 +0000 Date: Thu, 11 Apr 2019 08:33:13 -0700 From: Matthew Wilcox To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, mhocko@suse.com, rientjes@google.com, yuzhoujian@didichuxing.com, jrdr.linux@gmail.com, guro@fb.com, hannes@cmpxchg.org, penguin-kernel@I-love.SAKURA.ne.jp, ebiederm@xmission.com, shakeelb@google.com, christian@brauner.io, minchan@kernel.org, timmurray@google.com, dancol@google.com, joel@joelfernandes.org, jannh@google.com, linux-mm@kvack.org, lsf-pc@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [RFC 2/2] signal: extend pidfd_send_signal() to allow expedited process killing Message-ID: <20190411153313.GE22763@bombadil.infradead.org> References: <20190411014353.113252-1-surenb@google.com> <20190411014353.113252-3-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190411014353.113252-3-surenb@google.com> User-Agent: Mutt/1.9.2 (2017-12-15) 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 Wed, Apr 10, 2019 at 06:43:53PM -0700, Suren Baghdasaryan wrote: > Add new SS_EXPEDITE flag to be used when sending SIGKILL via > pidfd_send_signal() syscall to allow expedited memory reclaim of the > victim process. The usage of this flag is currently limited to SIGKILL > signal and only to privileged users. What is the downside of doing expedited memory reclaim? ie why not do it every time a process is going to die?