linux-kernel - Re: [External] : nfsd: memory leak when client does many file operations

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Date: Mon, 25 Mar 2024 20:11:23 +0000
From: Chuck Lever III <chuck.lever@...cle.com>
To: Jan Schunk <scpcom@....de>
CC: Jeff Layton <jlayton@...nel.org>, Neil Brown <neilb@...e.de>,
        Olga
 Kornievskaia <kolga@...app.com>, Dai Ngo <dai.ngo@...cle.com>,
        Tom Talpey
	<tom@...pey.com>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [External] : nfsd: memory leak when client does many file
 operations



> On Mar 25, 2024, at 3:55 PM, Jan Schunk <scpcom@....de> wrote:
> 
> The VM is now running 20 hours with 512MB RAM, no desktop, without the "noatime" mount option and without the "async" export option.
> 
> Currently there is no issue, but the memory usage is still contantly growing. It may just take longer before something happens.
> 
> top - 00:49:49 up 3 min,  1 user,  load average: 0,21, 0,19, 0,09
> Tasks: 111 total,   1 running, 110 sleeping,   0 stopped,   0 zombie
> %CPU(s):  0,2 us,  0,3 sy,  0,0 ni, 99,5 id,  0,0 wa,  0,0 hi,  0,0 si,  0,0 st 
> MiB Spch:    467,0 total,    302,3 free,     89,3 used,     88,1 buff/cache     
> MiB Swap:    975,0 total,    975,0 free,      0,0 used.    377,7 avail Spch
> 
> top - 15:05:39 up 14:19,  1 user,  load average: 1,87, 1,72, 1,65
> Tasks: 104 total,   1 running, 103 sleeping,   0 stopped,   0 zombie
> %CPU(s):  0,2 us,  4,9 sy,  0,0 ni, 53,3 id, 39,0 wa,  0,0 hi,  2,6 si,  0,0 st 
> MiB Spch:    467,0 total,     21,2 free,    147,1 used,    310,9 buff/cache     
> MiB Swap:    975,0 total,    952,9 free,     22,1 used.    319,9 avail Spch
> 
> top - 20:48:16 up 20:01,  1 user,  load average: 5,02, 2,72, 2,08
> Tasks: 104 total,   5 running,  99 sleeping,   0 stopped,   0 zombie
> %CPU(s):  0,2 us, 46,4 sy,  0,0 ni, 11,9 id,  2,3 wa,  0,0 hi, 39,2 si,  0,0 st 
> MiB Spch:    467,0 total,     16,9 free,    190,8 used,    271,6 buff/cache     
> MiB Swap:    975,0 total,    952,9 free,     22,1 used.    276,2 avail Spch

I don't see anything in your original memory dump that
might account for this. But I'm at a loss because I'm
a kernel developer, not a support guy -- I don't have
any tools or expertise that can troubleshoot a system
without rebuilding a kernel with instrumentation. My
first instinct is to tell you to bisect between v6.3
and v6.4, or at least enable kmemleak, but I'm guessing
you don't build your own kernels.

My only recourse at this point would be to try to
reproduce it myself, but unfortunately I've just
upgraded my whole lab to Fedora 39, and there's a grub
bug that prevents booting any custom-built kernel
on my hardware.

So I'm stuck until I can nail that down. Anyone else
care to help out?


--
Chuck Lever