From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B80DECA9EA0 for ; Fri, 25 Oct 2019 14:02:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C79D20679 for ; Fri, 25 Oct 2019 14:02:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572012137; bh=yu2re7QlOLOylGKR+ttvD8dXbCgph8uPZ6I6K2Me1Uk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fjxg2AGDleQkzfERGBS4ONmEmF9HVtpeqnH0FAMV7q9f4UKvhTkakBC8bCAwg+0EU YMoE5Py7RtAoU3rFTfQ0LVKMR0fr4UOVcg+Px/gKznhnL7cUhIT7vU/LqRYoYAlh7E mf8ESjhm0G4wy/w1+NqoTezFJM14lRlioN5tIt6s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395014AbfJYOCP (ORCPT ); Fri, 25 Oct 2019 10:02:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:53006 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2505386AbfJYN5y (ORCPT ); Fri, 25 Oct 2019 09:57:54 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 88E1D222CD; Fri, 25 Oct 2019 13:57:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572011873; bh=yu2re7QlOLOylGKR+ttvD8dXbCgph8uPZ6I6K2Me1Uk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vrrlSoFgxg4G3g4r4X20UQERfcR2qsRvm6jYmksYNJR5Z+vGP8RJJ/nAGQEFkowy5 Apl7+qo5Lt5ff/sEtMZybclkAcqXcjT6wpaYfZzouPW0GmLGZD+yypXNwOH6at7fzG byOXP/AubLv9cTDDc0g9yoFAgmBWorYq0DXChtzQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zhihao Cheng , Richard Weinberger , Sasha Levin , linux-mtd@lists.infradead.org Subject: [PATCH AUTOSEL 4.14 22/25] ubi: ubi_wl_get_peb: Increase the number of attempts while getting PEB Date: Fri, 25 Oct 2019 09:57:10 -0400 Message-Id: <20191025135715.25468-22-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191025135715.25468-1-sashal@kernel.org> References: <20191025135715.25468-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhihao Cheng [ Upstream commit 8615b94f029a4fb4306d3512aaf1c45f5fc24d4b ] Running stress test io_paral (A pressure ubi test in mtd-utils) on an UBI device with fewer PEBs (fastmap enabled) may cause ENOSPC errors and make UBI device read-only, but there are still free PEBs on the UBI device. This problem can be easily reproduced by performing the following steps on a 2-core machine: $ modprobe nandsim first_id_byte=0x20 second_id_byte=0x33 parts=80 $ modprobe ubi mtd="0,0" fm_autoconvert $ ./io_paral /dev/ubi0 We may see the following verbose: (output) [io_paral] update_volume():108: failed to write 380 bytes at offset 95920 of volume 2 [io_paral] update_volume():109: update: 97088 bytes [io_paral] write_thread():227: function pwrite() failed with error 28 (No space left on device) [io_paral] write_thread():229: cannot write 15872 bytes to offs 31744, wrote -1 (dmesg) ubi0 error: ubi_wl_get_peb [ubi]: Unable to get a free PEB from user WL pool ubi0 warning: ubi_eba_write_leb [ubi]: switch to read-only mode CPU: 0 PID: 2027 Comm: io_paral Not tainted 5.3.0-rc2-00001-g5986cd0 #9 ubi0 warning: try_write_vid_and_data [ubi]: failed to write VID header to LEB 2:5, PEB 18 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0 -0-ga698c8995f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x85/0xba ubi_eba_write_leb+0xa1e/0xa40 [ubi] vol_cdev_write+0x307/0x520 [ubi] vfs_write+0xfa/0x280 ksys_pwrite64+0xc5/0xe0 __x64_sys_pwrite64+0x22/0x30 do_syscall_64+0xbf/0x440 In function ubi_wl_get_peb, the operation of filling the pool (ubi_update_fastmap) with free PEBs and fetching a free PEB from the pool is not atomic. After thread A filling the pool with free PEB, free PEB may be taken away by thread B. When thread A checks the expression again, the condition is still unsatisfactory. At this time, there may still be free PEBs on UBI that can be filled into the pool. This patch increases the number of attempts to obtain PEB. An extreme case (No free PEBs left after creating test volumes) has been tested on different type of machines for 100 times. The biggest number of attempts are shown below: x86_64 arm64 2-core 4 4 4-core 8 4 8-core 4 4 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Sasha Levin --- drivers/mtd/ubi/fastmap-wl.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c index 69dd21679a30c..99aa30b28e46e 100644 --- a/drivers/mtd/ubi/fastmap-wl.c +++ b/drivers/mtd/ubi/fastmap-wl.c @@ -205,7 +205,7 @@ static int produce_free_peb(struct ubi_device *ubi) */ int ubi_wl_get_peb(struct ubi_device *ubi) { - int ret, retried = 0; + int ret, attempts = 0; struct ubi_fm_pool *pool = &ubi->fm_pool; struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool; @@ -230,12 +230,12 @@ int ubi_wl_get_peb(struct ubi_device *ubi) if (pool->used == pool->size) { spin_unlock(&ubi->wl_lock); - if (retried) { + attempts++; + if (attempts == 10) { ubi_err(ubi, "Unable to get a free PEB from user WL pool"); ret = -ENOSPC; goto out; } - retried = 1; up_read(&ubi->fm_eba_sem); ret = produce_free_peb(ubi); if (ret < 0) { -- 2.20.1