From nobody Thu Apr 16 00:51:52 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E1C1C433FE for ; Tue, 22 Nov 2022 14:22:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234062AbiKVOV6 (ORCPT ); Tue, 22 Nov 2022 09:21:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233207AbiKVOVq (ORCPT ); Tue, 22 Nov 2022 09:21:46 -0500 Received: from zju.edu.cn (spam.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DC88762394; Tue, 22 Nov 2022 06:21:44 -0800 (PST) Received: from localhost.localdomain (unknown [10.14.30.50]) by mail-app4 (Coremail) with SMTP id cS_KCgCHrN_o2nxjHR5BCA--.15646S3; Tue, 22 Nov 2022 22:21:40 +0800 (CST) From: Jinlong Chen To: axboe@kernel.dk Cc: hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nickyc975@zju.edu.cn Subject: [PATCH 1/4] elevator: update the document of elevator_switch Date: Tue, 22 Nov 2022 22:21:23 +0800 Message-Id: <94250961689ba7d2e67a7d9e7995a11166fedb31.1669126766.git.nickyc975@zju.edu.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: cS_KCgCHrN_o2nxjHR5BCA--.15646S3 X-Coremail-Antispam: 1UD129KBjvdXoW7GF4xKw1fuF4fXrWrCryxuFg_yoWkJwc_Z3 45tas7J34DWr4YgryfKF15trW09ws3XFy5Gws2grn3Xas0kFyvyr48ur17ur1xWa1UC343 A3yqv3WFvrnagjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbs8Fc2x0x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AK wVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20x vE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1l84ACjcxK6I8E 87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1lnxkEFVAIw20F6c xK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2Wl Yx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbV WUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij 64vIr41l42xK82IY6x8ErcxFaVAv8VW8uw4UJr1UMxC20s026xCaFVCjc4AY6r1j6r4UMI 8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AK xVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI 8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280 aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43 ZEXa7VUbHa0DUUUUU== X-CM-SenderInfo: qssqjiaqqzq6lmxovvfxof0/1tbiAgcCB1ZdtciuZAADs- Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" We no longer support falling back to the old io scheduler if switching to the new one fails. Update the document to indicate that. Fixes: a1ce35fa4985 ("block: remove dead elevator code") Signed-off-by: Jinlong Chen Reviewed-by: Christoph Hellwig --- block/elevator.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index a5bdc3b1e7e5..01aa9f38f22e 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -650,10 +650,10 @@ void elevator_init_mq(struct request_queue *q) } =20 /* - * switch to new_e io scheduler. be careful not to introduce deadlocks - - * we don't free the old io scheduler, before we have allocated what we - * need for the new one. this way we have a chance of going back to the old - * one, if the new one fails init for some reason. + * Switch to new_e io scheduler. + * + * If switching fails, we are most likely running out of memory and not ab= le + * to restore the old io scheduler, so leaving the io scheduler being none. */ int elevator_switch(struct request_queue *q, struct elevator_type *new_e) { --=20 2.34.1 From nobody Thu Apr 16 00:51:52 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FA30C43217 for ; Tue, 22 Nov 2022 14:22:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232704AbiKVOVy (ORCPT ); Tue, 22 Nov 2022 09:21:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233070AbiKVOVq (ORCPT ); Tue, 22 Nov 2022 09:21:46 -0500 Received: from zju.edu.cn (mail.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E4CD86829C; Tue, 22 Nov 2022 06:21:44 -0800 (PST) Received: from localhost.localdomain (unknown [10.14.30.50]) by mail-app4 (Coremail) with SMTP id cS_KCgCHrN_o2nxjHR5BCA--.15646S4; Tue, 22 Nov 2022 22:21:41 +0800 (CST) From: Jinlong Chen To: axboe@kernel.dk Cc: hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nickyc975@zju.edu.cn Subject: [PATCH 2/4] elevator: printk a warning if switching to a new io scheduler fails Date: Tue, 22 Nov 2022 22:21:24 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: cS_KCgCHrN_o2nxjHR5BCA--.15646S4 X-Coremail-Antispam: 1UD129KBjvdXoW7Jw4fGw4rGFykXry5uw18AFb_yoWxtrb_G3 y8K3Z7Jan8Gr4Yyr1fKF1YqF10vwn3JFy5Ww42qrn3J3W29Fyvyr10vr1xCr1kWFWUG3W3 Jw4q9rnrZw13KjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbs8Fc2x0x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AK wVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20x vE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1l84ACjcxK6I8E 87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1lnxkEFVAIw20F6c xK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2Wl Yx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbV WUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij 64vIr41l42xK82IY6x8ErcxFaVAv8VW8uw4UJr1UMxC20s026xCaFVCjc4AY6r1j6r4UMI 8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AK xVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI 8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280 aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43 ZEXa7VUbHa0DUUUUU== X-CM-SenderInfo: qssqjiaqqzq6lmxovvfxof0/1tbiAg4CB1ZdtciuiQAAsY Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" printk a warning to indicate that the io scheduler has been set to none if switching to a new io scheduler fails. Signed-off-by: Jinlong Chen Reviewed-by: Christoph Hellwig --- block/elevator.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/block/elevator.c b/block/elevator.c index 01aa9f38f22e..1fa45717b1d6 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -683,6 +683,12 @@ int elevator_switch(struct request_queue *q, struct el= evator_type *new_e) out_unfreeze: blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); + + if (ret) { + pr_warn("elv: switch to \"%s\" failed, falling back to \"none\"\n", + new_e->elevator_name); + } + return ret; } =20 --=20 2.34.1 From nobody Thu Apr 16 00:51:52 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 845ECC433FE for ; Tue, 22 Nov 2022 14:22:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232749AbiKVOWH (ORCPT ); Tue, 22 Nov 2022 09:22:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233378AbiKVOVs (ORCPT ); Tue, 22 Nov 2022 09:21:48 -0500 Received: from zju.edu.cn (mail.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E9AE2490A1; Tue, 22 Nov 2022 06:21:46 -0800 (PST) Received: from localhost.localdomain (unknown [10.14.30.50]) by mail-app4 (Coremail) with SMTP id cS_KCgCHrN_o2nxjHR5BCA--.15646S5; Tue, 22 Nov 2022 22:21:42 +0800 (CST) From: Jinlong Chen To: axboe@kernel.dk Cc: hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nickyc975@zju.edu.cn Subject: [PATCH 3/4] elevator: update the document of elevator_match Date: Tue, 22 Nov 2022 22:21:25 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: cS_KCgCHrN_o2nxjHR5BCA--.15646S5 X-Coremail-Antispam: 1UD129KBjvdXoW7Wr18Gr1rWr4xZw1fCF13twb_yoWDZwb_G3 yjy3Z7J34DJr1akF1IqF4Yqry7Zwn3Cry5Gr1xtFyxAayFgFnFyrZ7CryUCw1UXrW5C3W5 Cw4Duw17Zr1agjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbs8Fc2x0x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AK wVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20x vE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1l84ACjcxK6I8E 87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1lnxkEFVAIw20F6c xK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2Wl Yx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbV WUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij 64vIr41l42xK82IY6x8ErcxFaVAv8VW8uw4UJr1UMxC20s026xCaFVCjc4AY6r1j6r4UMI 8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AK xVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI 8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280 aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43 ZEXa7VUbHa0DUUUUU== X-CM-SenderInfo: qssqjiaqqzq6lmxovvfxof0/1tbiAg4CB1ZdtciuigABsa Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" elevator_match does not care about elevator_features any more. Remove related descriptions from its document. Fixes: ffb86425ee2c ("block: don't check for required features in elevator_= match") Signed-off-by: Jinlong Chen Reviewed-by: Christoph Hellwig --- block/elevator.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index 1fa45717b1d6..5287b39cd7a9 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -91,12 +91,11 @@ static inline bool elv_support_features(struct request_= queue *q, } =20 /** - * elevator_match - Test an elevator name and features + * elevator_match - Check whether @e's name or alias matches @name * @e: Scheduler to test * @name: Elevator name to test * - * Return true if the elevator @e name matches @name and if @e provides all - * the features specified by @required_features. + * Return true if the elevator @e's name or alias matches @name. */ static bool elevator_match(const struct elevator_type *e, const char *name) { --=20 2.34.1 From nobody Thu Apr 16 00:51:52 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 785AEC4332F for ; Tue, 22 Nov 2022 14:22:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232933AbiKVOWM (ORCPT ); Tue, 22 Nov 2022 09:22:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233492AbiKVOVs (ORCPT ); Tue, 22 Nov 2022 09:21:48 -0500 Received: from zju.edu.cn (mail.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 48A246829D; Tue, 22 Nov 2022 06:21:46 -0800 (PST) Received: from localhost.localdomain (unknown [10.14.30.50]) by mail-app4 (Coremail) with SMTP id cS_KCgCHrN_o2nxjHR5BCA--.15646S6; Tue, 22 Nov 2022 22:21:43 +0800 (CST) From: Jinlong Chen To: axboe@kernel.dk Cc: hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nickyc975@zju.edu.cn Subject: [PATCH 4/4] elevator: remove an outdated comment in elevator_change Date: Tue, 22 Nov 2022 22:21:26 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: cS_KCgCHrN_o2nxjHR5BCA--.15646S6 X-Coremail-Antispam: 1UD129KBjDUn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7v73 VFW2AGmfu7bjvjm3AaLaJ3UjIYCTnIWjp_UUUY37CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8w A2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j 6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAac4AC62xK8xCEY4vEwIxC4wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC 0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr 1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IE rcIFxwCF04k20xvY0x0EwIxGrwCF04k20xvE74AGY7Cv6cx26r4fKr1UJr1l4I8I3I0E4I kC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWU WwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr 0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWU JVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJb IYCTnIWIevJa73UjIFyTuYvjfUOlksUUUUU X-CM-SenderInfo: qssqjiaqqzq6lmxovvfxof0/1tbiAgECB1ZdtciuiwAAsV Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" mq is no longer a special case. Signed-off-by: Jinlong Chen Reviewed-by: Christoph Hellwig --- block/elevator.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index 5287b39cd7a9..599413620558 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -721,9 +721,6 @@ static int elevator_change(struct request_queue *q, con= st char *elevator_name) if (!blk_queue_registered(q)) return -ENOENT; =20 - /* - * Special case for mq, turn off scheduling - */ if (!strncmp(elevator_name, "none", 4)) { if (q->elevator) elevator_disable(q); --=20 2.34.1