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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: syzbot@lists.linux.dev 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