From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpo75.interia.pl (smtpo75.interia.pl [217.74.67.75]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 46C883D6CDE for ; Fri, 7 Aug 2026 07:31:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.74.67.75 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786087902; cv=none; b=jWoY7QtAwJN37rOjvGlRTlYkld/y6Hz9rNIR5A+RX2iG2olkzl8p4fSDE3GlWcTUCTi8c3nvjltfIb9pfk4ZSzi5wLW09J5LKQ/+yWw8A8YMhQKUCT8RRiwOXUo72LnkbBMpear8g3w9dN5NZ954jSdhEP7N545n2Vw5WFC2czY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786087902; c=relaxed/simple; bh=1VyDuJHYR+ciOz9BYEen75fLFOo4/umvL81BHUNGmEk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hRm24Xq3f6i8l6PL+7LySW2ADLK24cCSU/e7Hh9iuVycU39L8hReZOrm8eWVWfdK5ivAmbkUw8sq5eU7PGQ55qsfZxbkKSQUeJsvbG3eOmeRJdPXko8VNdln0xTAF4AImESnjDzg4+i57XCJ/1BFxePqFT+Z5TBF9cXA3nDQlcg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=poczta.fm; spf=pass smtp.mailfrom=poczta.fm; dkim=pass (1024-bit key) header.d=poczta.fm header.i=@poczta.fm header.b=WVimykD0; arc=none smtp.client-ip=217.74.67.75 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=poczta.fm Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=poczta.fm Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=poczta.fm header.i=@poczta.fm header.b="WVimykD0" Received: from nr200 (unknown [80.68.231.31]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by poczta.interia.pl (INTERIA.PL) with ESMTPSA; Fri, 7 Aug 2026 09:31:23 +0200 (CEST) Date: Fri, 7 Aug 2026 09:31:20 +0200 From: Slawomir Stepien To: Jakub Kicinski Cc: syzbot , syzkaller-bugs@googlegroups.com, Andrew Lunn , "David S. Miller" , Eric Dumazet , netdev@vger.kernel.org, Paolo Abeni , linux-kernel@vger.kernel.org, syzbot@lists.linux.dev Subject: Re: [PATCH] netdevsim: fix deadlock in nsim_bus_dev_max_vfs_write() Message-ID: References: <20260805160851.571ed66f@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260805160851.571ed66f@kernel.org> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poczta.fm; s=dk; t=1786087885; bh=qF4lEOy63wNW7hqrz8tDkLwya64utF2ElrqG9+tBOAw=; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type; b=WVimykD0rQZfu7zdYgBAq0HfudsyaL9tOFC8XsII51f52/7Fye4NmA64YHCrKQ+Xu 4jE22bBavpjZZH+8L4icizt8Uf/RDPr4+rUatuGTISKyg9w7XJOVqNY2si2aIU+KvD pNA3WFJo5NfLT5M1UWuG0HN00Zkp2+8Y+y77Pv8g= On sie 05, 2026 16:08, Jakub Kicinski wrote: > On Fri, 31 Jul 2026 09:55:04 +0000 (UTC) syzbot wrote: > > --- a/drivers/net/netdevsim/dev.c > > +++ b/drivers/net/netdevsim/dev.c > > @@ -273,7 +273,11 @@ static ssize_t nsim_bus_dev_max_vfs_write(struct file *file, > > Sorry to chime in poniewczasie. > Please delete this file. netdevsim is a harness for in-tree selftests, > none seems to be reading or writing the debugfs num_vfs AFAICT > so let's just drop it? That's true, but is netdevsim used *just* by the selftests (or was designed with only selftests in mind)? What if someone is using it without selftests? On the other hand: what sashiko found: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/b7bf56ea-7522-4163-acd5-aaa69ad03b3a%40mail.kernel.org is true: the same issue will be with e.g. break_health. So it seems to me that a better approach would be to change when the debugfs files are removed. It seems to me that change in nsim_drv_remove() might be easy, but what about nsim_dev_reload_down()...it seems it will have the same deadlock. Or am I missing something for this case? -- Slawomir Stepien