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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <187136.1708356611@warthog.procyon.org.uk> References: <187136.1708356611@warthog.procyon.org.uk> <20240205225726.3104808-1-dhowells@redhat.com> To: Steve French Cc: dhowells@redhat.com, Jeff Layton , Matthew Wilcox , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Christian Brauner , netfs@lists.linux.dev, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 00/12] netfs, cifs: Delegate high-level I/O to netfslib MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <187506.1708357334.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Mon, 19 Feb 2024 15:42:14 +0000 Message-ID: <187507.1708357334@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E294714000F X-Stat-Signature: d1xb41zhdd3pu4q5jbtikyjgg3q1j6gi X-Rspam-User: X-HE-Tag: 1708357342-830985 X-HE-Meta: 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 Zmy1WSgN zNHuiWwTlX7l3qfjBP2SNx6NWwFJAYyBU877tygf+5ziA7HqXydu4H1inntv99Yz66KcyVBFwfF9/2PXkywPaXB6nXaV7V7KSy9Oor4Ii8VyN5rLkYT672DPO3BiAaNB+1DZ3lMjqZoa1KPQtTFMKRk0A3maX17ED0X6B2umtAY2drzGzil4q/2HSfA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: David Howells wrote: > I don't suppose you can tell me what line smb2_readv_callback+0x50f/0x5b= 0 is? It's almost certainly the iov_iter_revert() here: switch (mid->mid_state) { case MID_RESPONSE_RECEIVED: credits.value =3D le16_to_cpu(shdr->CreditRequest); credits.instance =3D server->reconnect_instance; /* result already set, check signature */ if (server->sign && !mid->decrypted) { int rc; iov_iter_revert(&rqst.rq_iter, rdata->got_bytes); iov_iter_truncate(&rqst.rq_iter, rdata->got_bytes); The reason that the: [ 228.573737] kernel BUG at lib/iov_iter.c:582! happens is that we're trying to wind the iterator back before its start po= int. Now, the iterator is reinitialised at the beginning of the function: if (rdata->got_bytes) { rqst.rq_iter =3D rdata->subreq.io_iter; rqst.rq_iter_size =3D iov_iter_count(&rdata->subreq.io_iter); } so the reversion is probably unnecessary. Note that this can only happen if we're using signed messages: if (server->sign && !mid->decrypted) { as we wind back the iterator so that we can use it to feed the buffer to t= he hashing algorithm. David