From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754855AbaIQJft (ORCPT ); Wed, 17 Sep 2014 05:35:49 -0400 Received: from mga09.intel.com ([134.134.136.24]:45354 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751938AbaIQJfs (ORCPT ); Wed, 17 Sep 2014 05:35:48 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,539,1406617200"; d="scan'208";a="574328081" Message-ID: <1410946526.28850.120.camel@sauron.fi.intel.com> Subject: Re: [PATCH] UBI: Fix possible deadlock in erase_worker() From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Richard Weinberger Cc: dwmw2@infradead.org, computersforpeace@gmail.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Date: Wed, 17 Sep 2014 12:35:26 +0300 In-Reply-To: <1410853702-11616-1-git-send-email-richard@nod.at> References: <1410853702-11616-1-git-send-email-richard@nod.at> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-2.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-09-16 at 09:48 +0200, Richard Weinberger wrote: > If sync_erase() failes with EINTR, ENOMEM, EAGAIN or > EBUSY erase_worker() re-schedules the failed work. > This will lead to a deadlock because erase_worker() is called > with work_sem held in read mode. And schedule_erase() will take > this lock again. There is this code snippet: ubi_err("failed to erase PEB %d, error %d", pnum, err); kfree(wl_wrk); if (err == -EINTR || err == -ENOMEM || err == -EAGAIN || err == -EBUSY) { int err1; /* Re-schedule the LEB for erasure */ err1 = schedule_erase(ubi, e, vol_id, lnum, 0); if (err1) { err = err1; goto out_ro; } return err; } How about move 'kfree(wl_wrk)' down, and execute __schedule_ubi_work(ubi, wl_wrk) inside the 'if' clause instead? The fix would seem to be more elegant then. Hmm? -- Best Regards, Artem Bityutskiy