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 96ADBC433F5 for ; Fri, 15 Apr 2022 07:52:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351261AbiDOHyu (ORCPT ); Fri, 15 Apr 2022 03:54:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37784 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351263AbiDOHyu (ORCPT ); Fri, 15 Apr 2022 03:54:50 -0400 Received: from out1.migadu.com (out1.migadu.com [IPv6:2001:41d0:2:863f::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95D6EA76CA for ; Fri, 15 Apr 2022 00:52:22 -0700 (PDT) Message-ID: <201c00b5-b996-abea-468b-f747ca6cab0c@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1650009141; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qN6FAKTIziDCEQsqvZTAjz93+FXmRKFzKNsSpCoB9S4=; b=ZbMvCaxNberkhX67G5ncXol4B3RR2RTyueFckk+FEp6X3GCunpjwC2BIo6ljOFKLinX/q0 JkzSyCh7mHbC/R4AWqGHxTvE71hCMA9EDGHGCQXQvB37hfEZunMpTRuAeT0025iVa/PxCr GsXdgB+FALQLa5FYDv3asbboB5jzGJE= Date: Fri, 15 Apr 2022 15:52:11 +0800 MIME-Version: 1.0 Subject: Re: [PATCHv4 1/2] RDMA/rxe: Fix a dead lock problem To: Bob Pearson , jgg@ziepe.ca, leon@kernel.org, linux-rdma@vger.kernel.org References: <20220415195630.279510-1-yanjun.zhu@linux.dev> <0d88246e-c29a-27c0-95c5-da73f52e6a59@linux.dev> <726e75b0-c165-92f8-c367-1a5a777bc8b1@gmail.com> <5597e6eb-1543-6895-77fc-426e0a601338@linux.dev> <72d96848-3414-b665-d800-759986540aed@gmail.com> <11ec6705-a810-6ec9-86f1-584d29b656c6@linux.dev> <179daa3b-3f35-524e-6b8b-b9b4901ac5d2@gmail.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yanjun Zhu In-Reply-To: <179daa3b-3f35-524e-6b8b-b9b4901ac5d2@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 在 2022/4/15 15:49, Bob Pearson 写道: > On 4/15/22 02:42, Yanjun Zhu wrote: >> 在 2022/4/15 15:35, Bob Pearson 写道: >>> On 4/15/22 02:32, Yanjun Zhu wrote: >>>> 在 2022/4/15 15:22, Bob Pearson 写道: >>>>> On 4/15/22 01:49, Yanjun Zhu wrote: >>>>>> 在 2022/4/15 14:35, Bob Pearson 写道: >>>>>>> On 4/15/22 00:54, Yanjun Zhu wrote: >>>>>>>> 在 2022/4/15 13:37, Bob Pearson 写道: >>>>>>>>> On 4/15/22 14:56, yanjun.zhu@linux.dev wrote: >>>>>>>>>> From: Zhu Yanjun >>>>>>>>>> >>>>>>>>>> This is a dead lock problem. >>>>>>>>>> The xa_lock first is acquired in this: >>>>>>>>>> >>>>>>>>>> {SOFTIRQ-ON-W} state was registered at: >>>>>>>>>> >>>>>>>>>>       lock_acquire+0x1d2/0x5a0 >>>>>>>>>>       _raw_spin_lock+0x33/0x80 >>>>>>>>>>       __rxe_add_to_pool+0x183/0x230 [rdma_rxe] >>>>>>>>>>       __ib_alloc_pd+0xf9/0x550 [ib_core] >>>>>>>>>>       ib_mad_init_device+0x2d9/0xd20 [ib_core] >>>>>>>>>>       add_client_context+0x2fa/0x450 [ib_core] >>>>>>>>>>       enable_device_and_get+0x1b7/0x350 [ib_core] >>>>>>>>>>       ib_register_device+0x757/0xaf0 [ib_core] >>>>>>>>>>       rxe_register_device+0x2eb/0x390 [rdma_rxe] >>>>>>>>>>       rxe_net_add+0x83/0xc0 [rdma_rxe] >>>>>>>>>>       rxe_newlink+0x76/0x90 [rdma_rxe] >>>>>>>>>>       nldev_newlink+0x245/0x3e0 [ib_core] >>>>>>>>>>       rdma_nl_rcv_msg+0x2d4/0x790 [ib_core] >>>>>>>>>>       rdma_nl_rcv+0x1ca/0x3f0 [ib_core] >>>>>>>>>>       netlink_unicast+0x43b/0x640 >>>>>>>>>>       netlink_sendmsg+0x7eb/0xc40 >>>>>>>>>>       sock_sendmsg+0xe0/0x110 >>>>>>>>>>       __sys_sendto+0x1d7/0x2b0 >>>>>>>>>>       __x64_sys_sendto+0xdd/0x1b0 >>>>>>>>>>       do_syscall_64+0x37/0x80 >>>>>>>>>>       entry_SYSCALL_64_after_hwframe+0x44/0xae >>>>>>>>> There is a separate xarray for each object pool. So this one is >>>>>>>>> rxe->pd_pool.xa.xa_lock from rxe_alloc_pd(). >>>>>>>>> >>>>>>>>>> Then xa_lock is acquired in this: >>>>>>>>>> >>>>>>>>>> {IN-SOFTIRQ-W}: >>>>>>>>>> >>>>>>>>>> Call Trace: >>>>>>>>>>      >>>>>>>>>>       dump_stack_lvl+0x44/0x57 >>>>>>>>>>       mark_lock.part.52.cold.79+0x3c/0x46 >>>>>>>>>>       __lock_acquire+0x1565/0x34a0 >>>>>>>>>>       lock_acquire+0x1d2/0x5a0 >>>>>>>>>>       _raw_spin_lock_irqsave+0x42/0x90 >>>>>>>>>>       rxe_pool_get_index+0x72/0x1d0 [rdma_rxe] >>>>>>>>>>       rxe_get_av+0x168/0x2a0 [rdma_rxe] >>>>>>>>>>       rxe_requester+0x75b/0x4a90 [rdma_rxe] >>>>>>>>>>       rxe_do_task+0x134/0x230 [rdma_rxe] >>>>>>>>>>       tasklet_action_common.isra.12+0x1f7/0x2d0 >>>>>>>>>>       __do_softirq+0x1ea/0xa4c >>>>>>>>>>       run_ksoftirqd+0x32/0x60 >>>>>>>>>>       smpboot_thread_fn+0x503/0x860 >>>>>>>>>>       kthread+0x29b/0x340 >>>>>>>>>>       ret_from_fork+0x1f/0x30 >>>>>>>>> And this one is rxe->ah_pool.xa.xa_lock from rxe_requester >>>>>>>>> in the process of sending a UD packet from a work request >>>>>>>>> which contains the index of the ah. >>>>>>>>> >>>>>>>>> For your story to work there needs to be an another ah_pool.xa.xa_lock somewhere. >>>>>>>>> Let's assume it is there somewhere and it's from (a different) add_to_pool call >>>>>>>>> then the add_to_pool_ routine should disable interrupts when it gets the lock >>>>>>>>> with spin_lock_xxx. But only for AH objects. >>>>>>>>> >>>>>>>>> This may be old news. >>>>>>>> What do you mean? Please check the call trace in the bug. >>>>>>> I mean the trace you show here shows an instance of xa_lock being >>>>>>> acquired from the pd pool followed by an instance of xa_lock being >>>>>>> acquired from rxe_pool_get_index from the ah pool. They are different >>>>>>> locks. They can't deadlock against each other. So there must be >>>>>>> some other trace (not shown) that also gets xa_lock from the ah pool. >>>>>> Please check the bug report mail. The link is news://nntp.lore.kernel.org:119/CAHj4cs-MT13RiEsWXUAcX_H5jEtjsebuZgSeUcfptNVuELgjYQ@mail.gmail.com >>>>>> >>>>>> BTW, what is the update about wr crash caused by your xarray patches? >>>>>> >>>>>> Zhu Yanjun >>>>>> >>>>>>>> Zhu Yanjun >>>>>>>> >>>>>>>>>>      >>>>>>>>>> >>>>>>>>>>     From the above, in the function __rxe_add_to_pool, >>>>>>>>>> xa_lock is acquired. Then the function __rxe_add_to_pool >>>>>>>>>> is interrupted by softirq. The function >>>>>>>>>> rxe_pool_get_index will also acquire xa_lock. >>>>>>>>>> >>>>>>>>>> Finally, the dead lock appears. >>>>>>>>>> >>>>>>>>>> [  296.806097]        CPU0 >>>>>>>>>> [  296.808550]        ---- >>>>>>>>>> [  296.811003]   lock(&xa->xa_lock#15);  <----- __rxe_add_to_pool >>>>>>>>>> [  296.814583]   >>>>>>>>>> [  296.817209]     lock(&xa->xa_lock#15); <---- rxe_pool_get_index >>>>>>>>>> [  296.820961] >>>>>>>>>>                      *** DEADLOCK *** >>>>>>>>>> >>>>>>>>>> Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays") >>>>>>>>>> Reported-and-tested-by: Yi Zhang >>>>>>>>>> Signed-off-by: Zhu Yanjun >>>>>>>>>> --- >>>>>>>>>> V3->V4: xa_lock_irq locks are used. >>>>>>>>>> V2->V3: __rxe_add_to_pool is between spin_lock and spin_unlock, so >>>>>>>>>>             GFP_ATOMIC is used in __rxe_add_to_pool. >>>>>>>>>> V1->V2: Replace GFP_KERNEL with GFP_ATOMIC >>>>>>>>>> --- >>>>>>>>>>      drivers/infiniband/sw/rxe/rxe_pool.c | 20 ++++++++++++++------ >>>>>>>>>>      1 file changed, 14 insertions(+), 6 deletions(-) >>>>>>>>>> >>>>>>>>>> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c >>>>>>>>>> index 87066d04ed18..f1f06dc7e64f 100644 >>>>>>>>>> --- a/drivers/infiniband/sw/rxe/rxe_pool.c >>>>>>>>>> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c >>>>>>>>>> @@ -106,7 +106,7 @@ void rxe_pool_init(struct rxe_dev *rxe, struct rxe_pool *pool, >>>>>>>>>>            atomic_set(&pool->num_elem, 0); >>>>>>>>>>      -    xa_init_flags(&pool->xa, XA_FLAGS_ALLOC); >>>>>>>>>> +    xa_init_flags(&pool->xa, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ); >>>>>>>>>>          pool->limit.min = info->min_index; >>>>>>>>>>          pool->limit.max = info->max_index; >>>>>>>>>>      } >>>>>>>>>> @@ -138,8 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool) >>>>>>>>>>          elem->obj = obj; >>>>>>>>>>          kref_init(&elem->ref_cnt); >>>>>>>>>>      -    err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, >>>>>>>>>> -                  &pool->next, GFP_KERNEL); >>>>>>>>>> +    xa_lock_irq(&pool->xa); >>>>>>>>>> +    err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, >>>>>>>>>> +                &pool->next, GFP_KERNEL); >>>>>>>>>> +    xa_unlock_irq(&pool->xa); >>>>>>>>>>          if (err) >>>>>>>>>>              goto err_free; >>>>>>>>>>      @@ -155,6 +157,7 @@ void *rxe_alloc(struct rxe_pool *pool) >>>>>>>>>>      int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem) >>>>>>>>>>      { >>>>>>>>>>          int err; >>>>>>>>>> +    unsigned long flags; >>>>>>>>>>            if (WARN_ON(pool->flags & RXE_POOL_ALLOC)) >>>>>>>>>>              return -EINVAL; >>>>>>>>>> @@ -166,8 +169,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem) >>>>>>>>>>          elem->obj = (u8 *)elem - pool->elem_offset; >>>>>>>>>>          kref_init(&elem->ref_cnt); >>>>>>>>>>      -    err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, >>>>>>>>>> -                  &pool->next, GFP_KERNEL); >>>>>>>>>> +    xa_lock_irqsave(&pool->xa, flags); >>>>>>>>>> +    err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, >>>>>>>>>> +                &pool->next, GFP_ATOMIC); >>>>>>>>>> +    xa_unlock_irqrestore(&pool->xa, flags); >>>>>>>>>>          if (err) >>>>>>>>>>              goto err_cnt; >>>>>>>>>>      @@ -200,8 +205,11 @@ static void rxe_elem_release(struct kref *kref) >>>>>>>>>>      { >>>>>>>>>>          struct rxe_pool_elem *elem = container_of(kref, typeof(*elem), ref_cnt); >>>>>>>>>>          struct rxe_pool *pool = elem->pool; >>>>>>>>>> +    unsigned long flags; >>>>>>>>>>      -    xa_erase(&pool->xa, elem->index); >>>>>>>>>> +    xa_lock_irqsave(&pool->xa, flags); >>>>>>>>>> +    __xa_erase(&pool->xa, elem->index); >>>>>>>>>> +    xa_unlock_irqrestore(&pool->xa, flags); >>>>>>>>>>            if (pool->cleanup) >>>>>>>>>>              pool->cleanup(elem); >>>>> Here is my output. Everything passes there are no bugs or unexpected warnings in the kernel trace. >>>> If I understand you correctly, you mean that the bug reported by Zhang Yi does not exist? >>>> >>>> I can reproduce this bug with rping. >>>> >>>> You can not reproduce this bug. It does not mean that this bug does not exist. >>>> >>>> And with rping, I also found another wr NULL bug. From the mail, you can also verify this wr NULL bug. >>>> >>>> Let us foucus on this wr NULL bug. OK? >>>> >>>> Zhu Yanjun >>>> >>>>> bob@ubuntu-21:~/src/blktests$ sudo ./check -q srp >>>>> >>>>> srp/001 (Create and remove LUNs)                             [passed] >>>>> >>>>>       runtime  3.402s  ...  2.753s >>>>> >>>>> srp/002 (File I/O on top of multipath concurrently with logout and login (mq)) [passed]time  34.431s  ... >>>>> >>>>>       runtime  34.431s  ...  34.328s >>>>> >>>>> srp/003 (File I/O on top of multipath concurrently with logout and login (sq)) [not run] >>>>> >>>>>       legacy device mapper support is missing >>>>> >>>>> srp/004 (File I/O on top of multipath concurrently with logout and login (sq-on-srp/004 (File I/O on top of multipath concurrently with logout and login (sq-on-mq)) [not run] >>>>> >>>>>       legacy device mapper support is missing >>>>> >>>>> srp/005 (Direct I/O with large transfer sizes, cmd_sg_entries=255 and bs=4M) [passed] >>>>> >>>>>       runtime  14.332s  ...  12.919s >>>>> >>>>> srp/006 (Direct I/O with large transfer sizes, cmd_sg_entries=255 and bs=8M) [passed] >>>>> >>>>>       runtime  13.361s  ...  12.959s >>>>> >>>>> srp/007 (Direct I/O with large transfer sizes, cmd_sg_entries=1 and bs=4M) [passed] >>>>> >>>>>       runtime  14.293s  ...  12.912s >>>>> >>>>> srp/008 (Direct I/O with large transfer sizes, cmd_sg_entries=1 and bs=8M) [passed] >>>>> >>>>>       runtime  13.369s  ...  13.165s >>>>> >>>>> srp/009 (Buffered I/O with large transfer sizes, cmd_sg_entries=255 and bs=4M) [passed] >>>>> >>>>>       runtime  13.636s  ...  14.201s >>>>> >>>>> srp/010 (Buffered I/O with large transfer sizes, cmd_sg_entries=255 and bs=8M) [passed] >>>>> >>>>>       runtime  13.361s  ...  12.909s >>>>> >>>>> srp/011 (Block I/O on top of multipath concurrently with logout and login) [passed] >>>>> >>>>>       runtime  33.706s  ...  33.571s >>>>> >>>>> srp/012 (dm-mpath on top of multiple I/O schedulers)         [passed] >>>>> >>>>>       runtime  13.592s  ...  14.138s >>>>> >>>>> srp/013 (Direct I/O using a discontiguous buffer)            [passed] >>>>> >>>>>       runtime  3.230s  ...  3.513s >>>>> >>>>> srp/014 (Run sg_reset while I/O is ongoing)                  [passed] >>>>> >>>>>       runtime  33.070s  ...  33.059s >>>>> >>>>> srp/015 (File I/O on top of multipath concurrently with logout and login (mq) using the SoftiWARP (siw) dsrp/015 (File I/O on top of multipath concurrently with logout and login (mq) using the SoftiWARP (siw) driver) [passed].148s  ... >>>> you are using SoftiWARP (siw)? >>> not me. it is just the normal behavior of the srp/015 test case. it has always done that. my rdma-core >>> does support siw. >> Fine. >> Let us find the root cause of wr NULL problem. >> I revert xarray patches and fell back to original source code. >> This wr NULL problem does not exist. >> I am working on it. >> >> Hope we can fix this wr NULL problem very soon. > I have to go to bed. But the mr == NULL bug was fixed by the last 10 rxe pool patches. > I am sure it was the 8/10 patch which fixed it. Please explain the root cause to us and send out the single patch. Thanks a lot. Zhu Yanjun > I have never seen it once all the > rxe_pool patches were applied. > >> Zhu Yanjun >> >>>>>       runtime  35.148s  ...  34.974s >>>>> >>>>> bob@ubuntu-21:~/src/blktests$ >>>>> >>>>> Bob