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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5EE6AE77199 for ; Wed, 8 Jan 2025 10:31:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=RFF47yrkVJBHoWSFdhCxN9Pmr1E8ln/cV1XqKCoPz5s=; b=o4n0G8YmNUSn4GlO4KOayL29Qd /xQyP53fugAN+k9PIZJXTNB7/Y7qkx9JuMCVfy237sSAxfQs3rzSeYvJjP4RC/8XwOhaclAd6WiaF Cd5wJJH+eCcbERCl5MWY9fZfcVU3BhyRImb8vtEV49zte0Egc9ItdepOUT5gLpQ97AM9xhvD/7xWX 095peJVWH7NYOr3HyZk7b/rkbllVyKH+u5WkEOS8LVKA3Kkj6DrfKRi7uhws+qQ0KHJzjEmtded7A wdw/mfnLmUthl2k5RXiqjaZl4VpFfYMrY39vHq4AJn1ulUsAUE1yuYGFr4RjGB8EsXnRew6V9QWWL YLymi/9Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVTLb-00000007zez-0AEf; Wed, 08 Jan 2025 10:31:35 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVTLY-00000007ze2-0sKm for linux-nvme@lists.infradead.org; Wed, 08 Jan 2025 10:31:33 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736332290; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=RFF47yrkVJBHoWSFdhCxN9Pmr1E8ln/cV1XqKCoPz5s=; b=fa91VBslBPrG6+GNzABaASdGhXVcmqkfyc6n4gvSnQTBWF36fU/35/pNmR94pIifnmm1+E JOLQPJNBEM3Gl0y7bqzaCkKtuO6tEiHlhbIqRpXKTJkEhe8CIluRMItvXYhERKOkMae/7N cTobu6kRnUr6t9y/Ymid1rZ4CqJ5FvE= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-612-FT0j9aoPO92yisgQAdt35g-1; Wed, 08 Jan 2025 05:31:29 -0500 X-MC-Unique: FT0j9aoPO92yisgQAdt35g-1 X-Mimecast-MFC-AGG-ID: FT0j9aoPO92yisgQAdt35g Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B995719560BB; Wed, 8 Jan 2025 10:31:27 +0000 (UTC) Received: from fedora (unknown [10.72.116.74]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BC26F1956053; Wed, 8 Jan 2025 10:31:21 +0000 (UTC) Date: Wed, 8 Jan 2025 18:31:15 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , Damien Le Moal , Nilay Shroff , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, nbd@other.debian.org, linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net Subject: Re: [PATCH 03/10] block: don't update BLK_FEAT_POLL in __blk_mq_update_nr_hw_queues Message-ID: References: <20250108092520.1325324-1-hch@lst.de> <20250108092520.1325324-4-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250108092520.1325324-4-hch@lst.de> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250108_023132_316701_92D12F61 X-CRM114-Status: GOOD ( 19.94 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jan 08, 2025 at 10:25:00AM +0100, Christoph Hellwig wrote: > When __blk_mq_update_nr_hw_queues changes the number of tag sets, it > might have to disable poll queues. Currently it does so by adjusting > the BLK_FEAT_POLL, which is a bit against the intent of features that > describe hardware / driver capabilities, but more importantly causes > nasty lock order problems with the broadly held freeze when updating the > number of hardware queues and the limits lock. Fix this by leaving > BLK_FEAT_POLL alone, and instead check for the number of poll queues in > the bio submission and poll handlers. While this adds extra work to the > fast path, the variables are in cache lines used by these operations > anyway, so it should be cheap enough. > > Fixes: 8023e144f9d6 ("block: move the poll flag to queue_limits") > Signed-off-by: Christoph Hellwig > --- ... > /** > * submit_bio_noacct - re-submit a bio to the block device layer for I/O > * @bio: The bio describing the location in memory and on the device. > @@ -805,8 +817,7 @@ void submit_bio_noacct(struct bio *bio) > } > } > > - if (!(q->limits.features & BLK_FEAT_POLL) && > - (bio->bi_opf & REQ_POLLED)) { > + if ((bio->bi_opf & REQ_POLLED) && !bdev_can_poll(bdev)) { submit_bio_noacct() is called without grabbing .q_usage_counter, so tagset may be freed now, then use-after-free on q->tag_set? Thanks, Ming