netdev - Re: [PATCH] svcrdma: fix miss destroy percpu_counter in svc_rdma_proc

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Message-ID: <ZyUBYpOuHHHc2NoZ@tissot.1015granger.net>
Date: Fri, 1 Nov 2024 12:27:14 -0400
From: Chuck Lever <chuck.lever@...cle.com>
To: Simon Horman <horms@...nel.org>
Cc: Ye Bin <yebin@...weicloud.com>, trondmy@...nel.org, anna@...nel.org,
        jlayton@...nel.org, neilb@...e.de, okorniev@...hat.com,
        Dai.Ngo@...cle.com, tom@...pey.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        joel.granados@...nel.org, linux@...ssschuh.net,
        linux-nfs@...r.kernel.org, netdev@...r.kernel.org, yebin10@...wei.com,
        zhangxiaoxu5@...wei.com
Subject: Re: [PATCH] svcrdma: fix miss destroy percpu_counter in
 svc_rdma_proc_init()

On Fri, Nov 01, 2024 at 11:55:11AM +0000, Simon Horman wrote:
> On Thu, Oct 24, 2024 at 09:55:20AM +0800, Ye Bin wrote:
> > From: Ye Bin <yebin10@...wei.com>
> > 
> > There's issue as follows:
> > RPC: Registered rdma transport module.
> > RPC: Registered rdma backchannel transport module.
> > RPC: Unregistered rdma transport module.
> > RPC: Unregistered rdma backchannel transport module.
> > BUG: unable to handle page fault for address: fffffbfff80c609a
> > PGD 123fee067 P4D 123fee067 PUD 123fea067 PMD 10c624067 PTE 0
> > Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
> > RIP: 0010:percpu_counter_destroy_many+0xf7/0x2a0
> > Call Trace:
> >  <TASK>
> >  __die+0x1f/0x70
> >  page_fault_oops+0x2cd/0x860
> >  spurious_kernel_fault+0x36/0x450
> >  do_kern_addr_fault+0xca/0x100
> >  exc_page_fault+0x128/0x150
> >  asm_exc_page_fault+0x26/0x30
> >  percpu_counter_destroy_many+0xf7/0x2a0
> >  mmdrop+0x209/0x350
> >  finish_task_switch.isra.0+0x481/0x840
> >  schedule_tail+0xe/0xd0
> >  ret_from_fork+0x23/0x80
> >  ret_from_fork_asm+0x1a/0x30
> >  </TASK>
> > 
> > If register_sysctl() return NULL, then svc_rdma_proc_cleanup() will not
> > destroy the percpu counters which init in svc_rdma_proc_init().
> > If CONFIG_HOTPLUG_CPU is enabled, residual nodes may be in the
> > 'percpu_counters' list. The above issue may occur once the module is
> > removed. If the CONFIG_HOTPLUG_CPU configuration is not enabled, memory
> > leakage occurs.
> > To solve above issue just destroy all percpu counters when
> > register_sysctl() return NULL.
> > 
> > Fixes: 1e7e55731628 ("svcrdma: Restore read and write stats")
> > Fixes: 22df5a22462e ("svcrdma: Convert rdma_stat_sq_starve to a per-CPU counter")
> > Fixes: df971cd853c0 ("svcrdma: Convert rdma_stat_recv to a per-CPU counter")
> > Signed-off-by: Ye Bin <yebin10@...wei.com>
> > ---
> >  net/sunrpc/xprtrdma/svc_rdma.c | 18 +++++++++++++-----
> >  1 file changed, 13 insertions(+), 5 deletions(-)
> > 
> > diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
> > index 58ae6ec4f25b..11dff4d58195 100644
> > --- a/net/sunrpc/xprtrdma/svc_rdma.c
> > +++ b/net/sunrpc/xprtrdma/svc_rdma.c
> > @@ -233,25 +233,33 @@ static int svc_rdma_proc_init(void)
> >  
> >  	rc = percpu_counter_init(&svcrdma_stat_read, 0, GFP_KERNEL);
> >  	if (rc)
> > -		goto out_err;
> > +		goto err;
> >  	rc = percpu_counter_init(&svcrdma_stat_recv, 0, GFP_KERNEL);
> >  	if (rc)
> > -		goto out_err;
> > +		goto err_read;
> >  	rc = percpu_counter_init(&svcrdma_stat_sq_starve, 0, GFP_KERNEL);
> >  	if (rc)
> > -		goto out_err;
> > +		goto err_recv;
> >  	rc = percpu_counter_init(&svcrdma_stat_write, 0, GFP_KERNEL);
> >  	if (rc)
> > -		goto out_err;
> > +		goto err_sq;
> >  
> >  	svcrdma_table_header = register_sysctl("sunrpc/svc_rdma",
> >  					       svcrdma_parm_table);
> > +	if (!svcrdma_table_header)
> 
> Hi Ye Bin,
> 
> Should rc be set to a negative error value here,
> as is the case for other error cases above?
> 
> Flagged by Smatch.

I can add "rc = -ENOMEM;" to the applied patch.


> > +		goto err_write;
> > +
> >  	return 0;
> >  
> > -out_err:
> > +err_write:
> > +	percpu_counter_destroy(&svcrdma_stat_write);
> > +err_sq:
> >  	percpu_counter_destroy(&svcrdma_stat_sq_starve);
> > +err_recv:
> >  	percpu_counter_destroy(&svcrdma_stat_recv);
> > +err_read:
> >  	percpu_counter_destroy(&svcrdma_stat_read);
> > +err:
> >  	return rc;
> >  }
> >  
> > -- 
> > 2.34.1
> > 

-- 
Chuck Lever