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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A65CECAAD2 for ; Mon, 29 Aug 2022 15:48:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 373E8940009; Mon, 29 Aug 2022 11:48:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2FD1B940007; Mon, 29 Aug 2022 11:48:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 19DF8940009; Mon, 29 Aug 2022 11:48:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 07571940007 for ; Mon, 29 Aug 2022 11:48:27 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id D001116058A for ; Mon, 29 Aug 2022 15:48:26 +0000 (UTC) X-FDA: 79853062212.03.86BE733 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf12.hostedemail.com (Postfix) with ESMTP id 65D8540042 for ; Mon, 29 Aug 2022 15:48:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1661788105; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=GIxYeJVZ3AuDfEsQOkmwkGW18m9HV0rDJe5mYfX2jec=; b=IVF+0Hbl3YfH0jmlPvN2upCjEe9+RpokBxse/Cz0/tj62zRoN93e0hcK8YteslsyMgrHwd ENNbRPP97A7P9hs0aK4Em8iuLn2xG3/wl6V9Ko6CqRHWB23qgUqGDPGujqwAb5BFp4EzpA 6mM6/ccqNIg96Q9w7lHG/d4HSNHAZRc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-331-D1Qn4vfKMD67meAw8x86Pw-1; Mon, 29 Aug 2022 11:48:24 -0400 X-MC-Unique: D1Qn4vfKMD67meAw8x86Pw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2E92D8A520E; Mon, 29 Aug 2022 15:48:08 +0000 (UTC) Received: from raketa.redhat.com (unknown [10.40.192.88]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2B3F3492CAE; Mon, 29 Aug 2022 15:48:05 +0000 (UTC) From: Maurizio Lombardi To: vbabka@suse.cz Cc: linux-mm@kvack.org, rientjes@google.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, bigeasy@linutronix.de Subject: [PATCH RFC] mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context. Date: Mon, 29 Aug 2022 17:48:05 +0200 Message-Id: <20220829154805.1205507-1-mlombard@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661788106; a=rsa-sha256; cv=none; b=ESluIf3+o+1ZuUBUU6cB7dSP9cNwr13mQc2CuPjUIx8kIO0RvVQM8Vw9I2f9h1UxvrOdEu LBs64CkiNqrZlbCVcV2ShfKS7MBmyphPWsqmhe2a7YusGKQY/jv78BS5inscXndfcQbbnY 9eoaRxWTE4paHQPswR+g8dRrCPCQmyM= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IVF+0Hbl; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf12.hostedemail.com: domain of mlombard@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mlombard@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661788106; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=GIxYeJVZ3AuDfEsQOkmwkGW18m9HV0rDJe5mYfX2jec=; b=OHOT4WW4s7ycDG+1IozTfcGpGpRaRAMy8xPVvzqvFiy1xmB1YTsrDUBrVQveu4jZNk8vP6 AGdYRm6QoyvI2HIrMOFsgYBnEU1fzSHgniw7HKn6fScNdxgmSqQxavXK6VLAKKoXA86CP2 NKm2bLSB66uZEKVH+lHE0LnNZ6ohvw8= Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IVF+0Hbl; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf12.hostedemail.com: domain of mlombard@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mlombard@redhat.com X-Rspam-User: X-Rspamd-Server: rspam10 X-Stat-Signature: q3qrpbt4c884bswe9nqukd6bb7q1ezph X-Rspamd-Queue-Id: 65D8540042 X-HE-Tag: 1661788106-784572 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Commit 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context") moved all flush_cpu_slab() invocations to the global workqueue to avoid a problem related with deactivate_slab()/__free_slab() being called from an IRQ context on PREEMPT_RT kernels. When the flush_all_cpu_locked() function is called from a task context the flush_cpu_slab() function should be called directly, without deferring it to the global workqueue, otherwise a workqueue with the WQ_MEM_RECLAIM bit set could end up flushing a workqueue without the aforementioned bit, triggering a dependency issue. workqueue: WQ_MEM_RECLAIM nvme-delete-wq:nvme_delete_ctrl_work [nvme_core] is flushing !WQ_MEM_RECLAIM events:flush_cpu_slab WARNING: CPU: 37 PID: 410 at kernel/workqueue.c:2637 check_flush_dependency+0x10a/0x120 Workqueue: nvme-delete-wq nvme_delete_ctrl_work [nvme_core] RIP: 0010:check_flush_dependency+0x10a/0x120[ 453.262125] Call Trace: __flush_work.isra.0+0xbf/0x220 ? __queue_work+0x1dc/0x420 flush_all_cpus_locked+0xfb/0x120 __kmem_cache_shutdown+0x2b/0x320 kmem_cache_destroy+0x49/0x100 bioset_exit+0x143/0x190 blk_release_queue+0xb9/0x100 kobject_cleanup+0x37/0x130 nvme_fc_ctrl_free+0xc6/0x150 [nvme_fc] nvme_free_ctrl+0x1ac/0x2b0 [nvme_core] Fixes: 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context") Signed-off-by: Maurizio Lombardi --- mm/slub.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 862dbd9af4f5..d46ee90651d2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2681,30 +2681,34 @@ struct slub_flush_work { bool skip; }; +static void flush_cpu_slab(void *d) +{ + struct kmem_cache *s = d; + struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); + + if (c->slab) + flush_slab(s, c); + + unfreeze_partials(s); +} + /* * Flush cpu slab. * * Called from CPU work handler with migration disabled. */ -static void flush_cpu_slab(struct work_struct *w) +static void flush_cpu_slab_work(struct work_struct *w) { - struct kmem_cache *s; - struct kmem_cache_cpu *c; struct slub_flush_work *sfw; sfw = container_of(w, struct slub_flush_work, work); - s = sfw->s; - c = this_cpu_ptr(s->cpu_slab); - - if (c->slab) - flush_slab(s, c); - - unfreeze_partials(s); + flush_cpu_slab(sfw->s); } -static bool has_cpu_slab(int cpu, struct kmem_cache *s) +static bool has_cpu_slab(int cpu, void *info) { + struct kmem_cache *s = info; struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); return c->slab || slub_percpu_partial(c); @@ -2721,13 +2725,18 @@ static void flush_all_cpus_locked(struct kmem_cache *s) lockdep_assert_cpus_held(); mutex_lock(&flush_lock); + if (in_task()) { + on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1); + goto unlock_exit; + } + for_each_online_cpu(cpu) { sfw = &per_cpu(slub_flush, cpu); if (!has_cpu_slab(cpu, s)) { sfw->skip = true; continue; } - INIT_WORK(&sfw->work, flush_cpu_slab); + INIT_WORK(&sfw->work, flush_cpu_slab_work); sfw->skip = false; sfw->s = s; schedule_work_on(cpu, &sfw->work); @@ -2740,6 +2749,7 @@ static void flush_all_cpus_locked(struct kmem_cache *s) flush_work(&sfw->work); } +unlock_exit: mutex_unlock(&flush_lock); } -- 2.31.1