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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F264C5AD4C for ; Wed, 15 Nov 2023 19:57:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343608AbjKOT5c (ORCPT ); Wed, 15 Nov 2023 14:57:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343817AbjKOT5b (ORCPT ); Wed, 15 Nov 2023 14:57:31 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABB04C2 for ; Wed, 15 Nov 2023 11:57:28 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D20BC433C9; Wed, 15 Nov 2023 19:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700078248; bh=CDsT6093T1R5Ao+sIYHE6/68zcd/wrdbIYKBIgjUqUY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eJAh0dssFFUDC+GeYoKueaifAZmfrarp52nowQ7CrGm2jWGiTCpi8+WNVI8mQeW2N t/NwtJ0OemRrJvWVTJbQWEV5CU4GZ2p1hnoLvPS0fR0c+36/+F6oUKJRB3f0xbl0sl PzCqnhNv1OunzqXts84VcksgLQ2MSEbcuqD03A0o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tomas Glozar , Ira Weiny , Vishal Verma , Sasha Levin Subject: [PATCH 6.1 204/379] nd_btt: Make BTT lanes preemptible Date: Wed, 15 Nov 2023 14:24:39 -0500 Message-ID: <20231115192657.181036991@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115192645.143643130@linuxfoundation.org> References: <20231115192645.143643130@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tomas Glozar [ Upstream commit 36c75ce3bd299878fd9b238e9803d3817ddafbf3 ] nd_region_acquire_lane uses get_cpu, which disables preemption. This is an issue on PREEMPT_RT kernels, since btt_write_pg and also nd_region_acquire_lane itself take a spin lock, resulting in BUG: sleeping function called from invalid context. Fix the issue by replacing get_cpu with smp_process_id and migrate_disable when needed. This makes BTT operations preemptible, thus permitting the use of spin_lock. BUG example occurring when running ndctl tests on PREEMPT_RT kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4903, name: libndctl preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 Preemption disabled at: [] nd_region_acquire_lane+0x15/0x90 [libnvdimm] Call Trace: dump_stack_lvl+0x8e/0xb0 __might_resched+0x19b/0x250 rt_spin_lock+0x4c/0x100 ? btt_write_pg+0x2d7/0x500 [nd_btt] btt_write_pg+0x2d7/0x500 [nd_btt] ? local_clock_noinstr+0x9/0xc0 btt_submit_bio+0x16d/0x270 [nd_btt] __submit_bio+0x48/0x80 __submit_bio_noacct+0x7e/0x1e0 submit_bio_wait+0x58/0xb0 __blkdev_direct_IO_simple+0x107/0x240 ? inode_set_ctime_current+0x51/0x110 ? __pfx_submit_bio_wait_endio+0x10/0x10 blkdev_write_iter+0x1d8/0x290 vfs_write+0x237/0x330 ... Fixes: 5212e11fde4d ("nd_btt: atomic sector updates") Signed-off-by: Tomas Glozar Reviewed-by: Ira Weiny Reviewed-by: Vishal Verma Signed-off-by: Ira Weiny Signed-off-by: Sasha Levin --- drivers/nvdimm/region_devs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index e0875d3697624..7995f93db2a82 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -892,7 +892,8 @@ unsigned int nd_region_acquire_lane(struct nd_region *nd_region) { unsigned int cpu, lane; - cpu = get_cpu(); + migrate_disable(); + cpu = smp_processor_id(); if (nd_region->num_lanes < nr_cpu_ids) { struct nd_percpu_lane *ndl_lock, *ndl_count; @@ -911,16 +912,15 @@ EXPORT_SYMBOL(nd_region_acquire_lane); void nd_region_release_lane(struct nd_region *nd_region, unsigned int lane) { if (nd_region->num_lanes < nr_cpu_ids) { - unsigned int cpu = get_cpu(); + unsigned int cpu = smp_processor_id(); struct nd_percpu_lane *ndl_lock, *ndl_count; ndl_count = per_cpu_ptr(nd_region->lane, cpu); ndl_lock = per_cpu_ptr(nd_region->lane, lane); if (--ndl_count->count == 0) spin_unlock(&ndl_lock->lock); - put_cpu(); } - put_cpu(); + migrate_enable(); } EXPORT_SYMBOL(nd_region_release_lane); -- 2.42.0