From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from abb.hmeau.com (abb.hmeau.com [144.6.53.87]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A5BE1A6; Fri, 1 Dec 2023 15:39:00 -0800 (PST) Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1r9D5s-005xu4-QL; Sat, 02 Dec 2023 07:38:49 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Sat, 02 Dec 2023 07:38:58 +0800 Date: Sat, 2 Dec 2023 07:38:58 +0800 From: Herbert Xu To: Edward Adam Davis Cc: davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, olivia@selenic.com, syzbot+c52ab18308964d248092@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] hwrng: core - fix task hung in hwrng_fillfn Message-ID: References: Precedence: bulk X-Mailing-List: linux-crypto@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: On Fri, Dec 01, 2023 at 08:34:12PM +0800, Edward Adam Davis wrote: > > According to splat, after a page fault occurred, the attempt to retrieve > rcu_read_lock() failed, resulting in a timeout of 143s. This is my speculation. Oh I see what's going on. The reproducer is mapping /dev/hwrng, so the write to user-space is then triggering another read which then dead-locks. Let me think about this. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt