From nobody Mon Dec 27 18:58:02 2021 X-Original-To: current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 92A481924DBE for ; Mon, 27 Dec 2021 18:58:04 +0000 (UTC) (envelope-from glebius@freebsd.org) Received: from cell.glebi.us (glebi.us [162.251.186.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "cell.glebi.us", Issuer "cell.glebi.us" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4JN6PS2QGzz3t4D; Mon, 27 Dec 2021 18:58:04 +0000 (UTC) (envelope-from glebius@freebsd.org) Received: from cell.glebi.us (localhost [127.0.0.1]) by cell.glebi.us (8.16.1/8.16.1) with ESMTPS id 1BRIw2JI005261 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 27 Dec 2021 10:58:03 -0800 (PST) (envelope-from glebius@freebsd.org) Received: (from glebius@localhost) by cell.glebi.us (8.16.1/8.16.1/Submit) id 1BRIw2Jc005260; Mon, 27 Dec 2021 10:58:02 -0800 (PST) (envelope-from glebius@freebsd.org) X-Authentication-Warning: cell.glebi.us: glebius set sender to glebius@freebsd.org using -f Date: Mon, 27 Dec 2021 10:58:02 -0800 From: Gleb Smirnoff To: Alexander Motin Cc: Larry Rosenman , current@freebsd.org Subject: Re: My -CURRENT crashes.... Message-ID: References: <286c830efc0e12e3e7a7e9b2ede31c28@lerctr.org> <45ee5689-b24c-51b5-d7b7-33fd73ee7dce@FreeBSD.org> List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45ee5689-b24c-51b5-d7b7-33fd73ee7dce@FreeBSD.org> X-Rspamd-Queue-Id: 4JN6PS2QGzz3t4D X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-ThisMailContainsUnwantedMimeParts: N On Mon, Dec 27, 2021 at 01:43:01PM -0500, Alexander Motin wrote: A> > This allows us to deduct that the callout belongs to proc subsystem and A> > we can retrieve the proc it points to: c_lock - 0x128 = 0xfffff8030521e548 A> > It is ccache in PRS_NORMAL state. And the "tmp" in our stack frame is its A> > p_itcallout. A> > A> > So there is something that would zero out most of the p_itcallout while A> > it is scheduled? A> A> So carefully zero it, but keep the lock pointer... The only way that A> comes to mind is callout_init_mtx() in do_fork() if we assume the A> process has completed and the struct proc was reused. I guess if we A> could somehow leak scheduled callout in exit1(). May be we could add A> some more assertions to try catch callout still being active there. Note that _callout_stop_safe(p_itcallout) is the only place in kernel where CS_EXECUTING is used. -- Gleb Smirnoff