From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Galbraith Subject: Re: [PATCH RT] blk-mq: revert raw locks, post pone notifier to POST_DEAD Date: Wed, 07 May 2014 11:07:17 +0200 Message-ID: <1399453637.5142.40.camel@marge.simpson.net> References: <1399135344-5349-1-git-send-email-bigeasy@linutronix.de> <1399136587.5158.29.camel@marge.simpson.net> <5369EC9E.1010904@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-rt-users@vger.kernel.org To: Sebastian Andrzej Siewior Return-path: Received: from mail-ee0-f53.google.com ([74.125.83.53]:33669 "EHLO mail-ee0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755441AbaEGJHU (ORCPT ); Wed, 7 May 2014 05:07:20 -0400 Received: by mail-ee0-f53.google.com with SMTP id c13so483472eek.40 for ; Wed, 07 May 2014 02:07:19 -0700 (PDT) In-Reply-To: <5369EC9E.1010904@linutronix.de> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Wed, 2014-05-07 at 10:19 +0200, Sebastian Andrzej Siewior wrote: > On 05/03/2014 07:03 PM, Mike Galbraith wrote: > >> Mike, I see that lockdep splat (sleeping while atomic) during cpu-hotplug. > >> Don't you see this, too? > > > > Nope, didn't. > > Hmm. blk_mq_hctx_notify(). It does > spin_lock(&ctx->lock); > > Isn't this a sleeping spinlock for you or don't get here at all? Hm, cts->lock... git@marge:~/suse/scratch_area/linux-3.12-SLE12-RT> grep -IR cpu_lock block git@marge:~/suse/scratch_area/linux-3.12-SLE12-RT> (here lock lock lock, here boy) marge:/usr/local/src/kernel/linux-3.x.git # grep -IR cpu_lock block marge:/usr/local/src/kernel/linux-3.x.git # marge:/usr/local/src/kernel/linux-3.14 # grep -IR cpu_lock block marge:/usr/local/src/kernel/linux-3.14 # (what the..) marge:/usr/local/src/kernel/linux-3.14-rt # grep -IR cpu_lock block block/blk-mq.c: spin_lock(&ctx->cpu_lock); block/blk-mq.c: spin_unlock(&ctx->cpu_lock); block/blk-mq.c: spin_unlock(&ctx->cpu_lock); block/blk-mq.c: spin_lock(&ctx->cpu_lock); block/blk-mq.c: spin_lock_init(&__ctx->cpu_lock); block/blk-mq.h: spinlock_t cpu_lock; marge:/usr/local/src/kernel/linux-3.14-rt # (aha!) Nope, I definitely don't get there. -Mike