From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 8BC2E38F82 for ; Wed, 8 Jan 2025 10:31:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332295; cv=none; b=aliVMyTIEL7T/+SeH33Fe0/1XF1jJyy8wwAMOXMLO0mf8FHXb1smPc1VHluNivn8z7ULiwcttC1UF44Aqn6N04aUSGsIVYAbH+siGny0sMBXn5QOJvLQp+4C07jxmjO71jZJ0rloqgw8YPHdwy7ThWHlWca+XCVV+ecEFYCzGMU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332295; c=relaxed/simple; bh=GC5JEn1xkVJYpSe7GCdjpBSC4tLkuO1AptJ0Bv/l9EQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tH76xW8arnahICNVfoZJOqZFIQ8K5RfWydjxyq9USbh/N18UkfgNlBwwWgibk71XRV01xC5VQdSZ1RXHLRlu6kt+PUMiYZFmZJGLaFOzJfeS62Ru3vPZ2MeCVhjFa72X/2YXCGynbrKy/XyTW5xA/va8BmzYmTNJy1WGgSk0uxo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=N4FJgxbo; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="N4FJgxbo" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736332292; 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=N4FJgxboaWIA51QQsNnO0xgJnoXRaOSMBuYthDrMkm85cIVKCtSmVvb4cIKFTahGSoD0I7 FvmNy5WLdAhGUUByGV06utfpCJOfkz8BIj7QJ2n0BGJzm//fSCW0vWx3oTOMlf9zGgUVW1 wavkjr6BkBmxtZ6sDvoVcR9LezoLKEs= 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> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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