From owner-freebsd-bugs@FreeBSD.ORG Fri May 29 16:27:05 2015 Return-Path: Delivered-To: freebsd-bugs@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id EAC79B31 for ; Fri, 29 May 2015 16:27:05 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id BB50F1B21 for ; Fri, 29 May 2015 16:27:05 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.14.9/8.14.9) with ESMTP id t4TGR5sl048651 for ; Fri, 29 May 2015 16:27:05 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 200493] Killing pid 11 (idle) wedges the disk IO Date: Fri, 29 May 2015 16:27:05 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.0-CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: commit-hook@freebsd.org X-Bugzilla-Status: New X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 May 2015 16:27:06 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=200493 --- Comment #11 from commit-hook@freebsd.org --- A commit references this bug: Author: kib Date: Fri May 29 16:26:08 UTC 2015 New revision: 283745 URL: https://svnweb.freebsd.org/changeset/base/283745 Log: When delivering a signal with default disposition to the thread, tdsigwakeup() increases the priority of the low-priority threads, to give them a chance to be terminated timely. Also, kernel allows user to signal kernel processes. The combined effect is that signalling idle process bump a priority of the selected delivery thread, which starts eating CPU. Check for the delivery thread be an idle thread and do not raise its priority then. The signal delivery to the kernel threads must be opt-in feature. Kernel thread should explicitely declare the ability to handle signals directed to it. E.g., nfsd threads check for signal as an indication of exit request. Most threads do not handle signals at all, and queuing the signal to them causes odd side-effects. Most innocent consequence is the memory leak due to queued ksiginfo, which is never deleted from the sigqueue. Code to prevent even queuing signals to the kernel threads is trivial, but it requires careful examination of each call to kproc/kthread creation to decide should the signalling be allowed. The commit is a stop-gap measure which fixes the immediate case for now. PR: 200493 Reported and tested by: trasz Discussed with: trasz, emaste Sponsored by: The FreeBSD Foundation MFC after: 1 week Changes: head/sys/kern/kern_sig.c -- You are receiving this mail because: You are the assignee for the bug.