From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751409AbdARHxx (ORCPT ); Wed, 18 Jan 2017 02:53:53 -0500 Received: from lelnx194.ext.ti.com ([198.47.27.80]:55522 "EHLO lelnx194.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751150AbdARHxw (ORCPT ); Wed, 18 Jan 2017 02:53:52 -0500 Subject: Re: [RFC PATCH] initramfs: finish fput() before accessing any binary from initramfs To: Tero Kristo , References: <20170117111456.2269-1-lokeshvutla@ti.com> <35e88dbe-f269-2558-c3b7-9ba228a70504@ti.com> CC: , Linux ARM Mailing List , Sekhar Nori , Nishanth Menon From: Lokesh Vutla Message-ID: <92bbc86b-77b8-7b06-5009-a885831c19d5@ti.com> Date: Wed, 18 Jan 2017 11:21:11 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <35e88dbe-f269-2558-c3b7-9ba228a70504@ti.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 17 January 2017 06:23 PM, Tero Kristo wrote: > On 17/01/17 13:14, Lokesh Vutla wrote: >> commit 4a9d4b024a31 ("switch fput to task_work_add") implements a >> schedule_work() for completing fput(), but did not guarantee calling >> __fput() after unpacking initramfs. Because of this, there is a >> possibility that during boot a driver can see ETXTBSY when it tries >> to load a binary from initramfs as fput() is still pending on that >> binary. This patch makes sure that fput() is completed after unpacking >> initramfs. > > Good find there. > >> >> Signed-off-by: Lokesh Vutla >> --- >> >> - Reproduced on TI K2HK EVM. K2HK Queue Manager subsystem driver[1] tries >> to load a firmware from initramfs during boot. Sometimes loading of this >> firmware fails with error ETXTBSY. Digging a bit more observed that >> deny_write_access() is returning ETXTBSY as inode->i_writecount is > 0 >> for that file. This is because Unpacking initramfs does a >> get_write_access(from open) but hasn't done put_write_access(from fput) >> as it hasn't been scheduled yet. >> >> [1] >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/soc/ti/knav_qmss_queue.c >> >> >> init/initramfs.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/init/initramfs.c b/init/initramfs.c >> index b32ad7d97ac9..c42c69b48a4b 100644 >> --- a/init/initramfs.c >> +++ b/init/initramfs.c >> @@ -18,6 +18,7 @@ >> #include >> #include >> #include >> +#include >> >> static ssize_t __init xwrite(int fd, const char *p, size_t count) >> { >> @@ -652,6 +653,7 @@ static int __init populate_rootfs(void) >> * us a chance to load before device_initcalls. >> */ >> load_default_modules(); >> + flush_delayed_fput(); > > Shouldn't the flush be called before the load_default_modules() though? Good point. Will wait for sometime for more comments and then repost it. Thanks and regards, Lokesh