From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 95D8743AA6 for ; Wed, 15 Nov 2023 20:44:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CDloFdc5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 455E7C433C8; Wed, 15 Nov 2023 20:44:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700081097; bh=sbJVwXnix2nKPDkPosppvwcdwVszQ/eH4KaLWY8amPA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CDloFdc5Q/MItM5cYeibU/V1B3VFh1Zt9ukmIwyrCi8KRdsb2k0r+oevipVKEdhEz 7nSi48NlJCwYBkI1I8+exO0XtKAaiIOXz6srbQ0uOdJ0odE7JRUuBykCF7pPPry831 nd8BEo0aoNPXTgWa+FYtimTygxZVpbdUs3oc8D7A= 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 4.19 37/88] nd_btt: Make BTT lanes preemptible Date: Wed, 15 Nov 2023 15:35:49 -0500 Message-ID: <20231115191428.408798121@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115191426.221330369@linuxfoundation.org> References: <20231115191426.221330369@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-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 609fc450522a1..89539a078623c 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -947,7 +947,8 @@ 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; @@ -966,16 +967,15 @@ 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