From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F1F2C4332F for ; Tue, 12 Dec 2023 07:00:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230238AbjLLHAa (ORCPT ); Tue, 12 Dec 2023 02:00:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229449AbjLLHA2 (ORCPT ); Tue, 12 Dec 2023 02:00:28 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1624BF for ; Mon, 11 Dec 2023 23:00:34 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F75CC433C9; Tue, 12 Dec 2023 07:00:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702364433; bh=hY9xSJJblbAWJZgHacsmi+/6bjhkQNzcCd6xAObVzO8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QwQWBbzvgGSjltK/FvX5mtoHzBN8xqpKHEGvpvsOg8PDzdfe9PWTN9pG0ljZv4Uev lWf28z4v1VflknmJNAPCctcj1gs/ubZQ/hBPeR/78S6oICkoPcHoOkD6CqM8cjIUq0 GsCm0jSZB2VKgYElS6tpWVDx5b0KbNblQRU/pqlqt7kArgsqyqjCCSpYCHIu8pm5ff YTM/VEnPuigfxbDat4ygU7TGyvd0rba11kT9PQv7jXIQugaI57F//PCPMgyMYHCpa5 K9P2a2KCIMzO1dZKVw0UevvgZ5K61qiRUqoSCofggGju0Dz6APDoFvD/2sQjWvnrQv TjSo1Eoc7Hnsg== Date: Tue, 12 Dec 2023 09:00:28 +0200 From: Leon Romanovsky To: Daniel Vacek Cc: Jason Gunthorpe , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Yuya Fujita-bishamonten Subject: Re: [PATCH 1/2] IB/ipoib: Fix mcast list locking Message-ID: <20231212070028.GJ4870@unreal> References: <20231211130426.1500427-1-neelx@redhat.com> <20231211130426.1500427-2-neelx@redhat.com> <20231211134542.GG4870@unreal> <20231211150657.GH4870@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 11, 2023 at 05:00:11PM +0100, Daniel Vacek wrote: > On Mon, Dec 11, 2023 at 4:18 PM Leon Romanovsky wrote: > > > > What about the following change instead of adding extra lock to already > > too much complicated IPoIB? > > Yeah, that's the other option should also work I believe. And it > simplifies the code nicely. > > The allocated mcast_member and mcast_group structures are small enough > so that slab (by default) should not need more then order 1 block to > eventually extend/refill the full kmalloc-256 cache. Some arches will > even use order 0 I believe. > And unless I'm missing something I do not see any other sleeps in that path. > > That said, as long as you are fine with occasional failures under > memory pressure, it looks OK to me. Yes, IMHO change from GFP_KERNEL to be GFP_ATOMIC is safer than adding extra lock. Thanks > > --nX > > > diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c > > index 5b3154503bf4..bca80fe07584 100644 > > --- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c > > +++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c > > @@ -531,21 +531,17 @@ static int ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast) > > if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)) > > rec.join_state = SENDONLY_FULLMEMBER_JOIN; > > } > > - spin_unlock_irq(&priv->lock); > > > > multicast = ib_sa_join_multicast(&ipoib_sa_client, priv->ca, priv->port, > > - &rec, comp_mask, GFP_KERNEL, > > + &rec, comp_mask, GFP_ATOMIC, > > ipoib_mcast_join_complete, mcast); > > - spin_lock_irq(&priv->lock); > > if (IS_ERR(multicast)) { > > ret = PTR_ERR(multicast); > > ipoib_warn(priv, "ib_sa_join_multicast failed, status %d\n", ret); > > /* Requeue this join task with a backoff delay */ > > __ipoib_mcast_schedule_join_thread(priv, mcast, 1); > > clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags); > > - spin_unlock_irq(&priv->lock); > > complete(&mcast->done); > > - spin_lock_irq(&priv->lock); > > } > > return 0; > > } > > > > > > > > > > --nX > > > > > > > > > > Thanks > > > > > > > > > Unfortunately we could not reproduce the lockup and confirm this fix but > > > > > based on the code review I think this fix should address such lockups. > > > > > > > > > > crash> bc 31 > > > > > PID: 747 TASK: ff1c6a1a007e8000 CPU: 31 COMMAND: "kworker/u72:2" > > > > > -- > > > > > [exception RIP: ipoib_mcast_join_task+0x1b1] > > > > > RIP: ffffffffc0944ac1 RSP: ff646f199a8c7e00 RFLAGS: 00000002 > > > > > RAX: 0000000000000000 RBX: ff1c6a1a04dc82f8 RCX: 0000000000000000 > > > > > work (&priv->mcast_task{,.work}) > > > > > RDX: ff1c6a192d60ac68 RSI: 0000000000000286 RDI: ff1c6a1a04dc8000 > > > > > &mcast->list > > > > > RBP: ff646f199a8c7e90 R8: ff1c699980019420 R9: ff1c6a1920c9a000 > > > > > R10: ff646f199a8c7e00 R11: ff1c6a191a7d9800 R12: ff1c6a192d60ac00 > > > > > mcast > > > > > R13: ff1c6a1d82200000 R14: ff1c6a1a04dc8000 R15: ff1c6a1a04dc82d8 > > > > > dev priv (&priv->lock) &priv->multicast_list (aka head) > > > > > ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 > > > > > --- --- > > > > > #5 [ff646f199a8c7e00] ipoib_mcast_join_task+0x1b1 at ffffffffc0944ac1 [ib_ipoib] > > > > > #6 [ff646f199a8c7e98] process_one_work+0x1a7 at ffffffff9bf10967 > > > > > > > > > > crash> rx ff646f199a8c7e68 > > > > > ff646f199a8c7e68: ff1c6a1a04dc82f8 <<< work = &priv->mcast_task.work > > > > > > > > > > crash> list -hO ipoib_dev_priv.multicast_list ff1c6a1a04dc8000 > > > > > (empty) > > > > > > > > > > crash> ipoib_dev_priv.mcast_task.work.func,mcast_mutex.owner.counter ff1c6a1a04dc8000 > > > > > mcast_task.work.func = 0xffffffffc0944910 , > > > > > mcast_mutex.owner.counter = 0xff1c69998efec000 > > > > > > > > > > crash> b 8 > > > > > PID: 8 TASK: ff1c69998efec000 CPU: 33 COMMAND: "kworker/u72:0" > > > > > -- > > > > > #3 [ff646f1980153d50] wait_for_completion+0x96 at ffffffff9c7d7646 > > > > > #4 [ff646f1980153d90] ipoib_mcast_remove_list+0x56 at ffffffffc0944dc6 [ib_ipoib] > > > > > #5 [ff646f1980153de8] ipoib_mcast_dev_flush+0x1a7 at ffffffffc09455a7 [ib_ipoib] > > > > > #6 [ff646f1980153e58] __ipoib_ib_dev_flush+0x1a4 at ffffffffc09431a4 [ib_ipoib] > > > > > #7 [ff646f1980153e98] process_one_work+0x1a7 at ffffffff9bf10967 > > > > > > > > > > crash> rx ff646f1980153e68 > > > > > ff646f1980153e68: ff1c6a1a04dc83f0 <<< work = &priv->flush_light > > > > > > > > > > crash> ipoib_dev_priv.flush_light.func,broadcast ff1c6a1a04dc8000 > > > > > flush_light.func = 0xffffffffc0943820 , > > > > > broadcast = 0x0, > > > > > > > > > > The mcast(s) on the &remove_list (the remaining part of the ex &priv->multicast_list): > > > > > > > > > > crash> list -s ipoib_mcast.done.done ipoib_mcast.list -H ff646f1980153e10 | paste - - > > > > > ff1c6a192bd0c200 done.done = 0x0, > > > > > ff1c6a192d60ac00 done.done = 0x0, > > > > > > > > > > Reported-by: Yuya Fujita-bishamonten > > > > > Signed-off-by: Daniel Vacek > > > > > --- > > > > > drivers/infiniband/ulp/ipoib/ipoib_multicast.c | 3 +++ > > > > > 1 file changed, 3 insertions(+) > > > > > > > > > > diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c > > > > > index 5b3154503bf4..8e4f2c8839be 100644 > > > > > --- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c > > > > > +++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c > > > > > @@ -580,6 +580,7 @@ void ipoib_mcast_join_task(struct work_struct *work) > > > > > } > > > > > netif_addr_unlock_bh(dev); > > > > > > > > > > + mutex_lock(&priv->mcast_mutex); > > > > > spin_lock_irq(&priv->lock); > > > > > if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) > > > > > goto out; > > > > > @@ -634,6 +635,7 @@ void ipoib_mcast_join_task(struct work_struct *work) > > > > > /* Found the next unjoined group */ > > > > > if (ipoib_mcast_join(dev, mcast)) { > > > > > spin_unlock_irq(&priv->lock); > > > > > + mutex_unlock(&priv->mcast_mutex); > > > > > return; > > > > > } > > > > > } else if (!delay_until || > > > > > @@ -655,6 +657,7 @@ void ipoib_mcast_join_task(struct work_struct *work) > > > > > ipoib_mcast_join(dev, mcast); > > > > > > > > > > spin_unlock_irq(&priv->lock); > > > > > + mutex_unlock(&priv->mcast_mutex); > > > > > } > > > > > > > > > > void ipoib_mcast_start_thread(struct net_device *dev) > > > > > -- > > > > > 2.43.0 > > > > > > > > > > > > > > >