Re: [PATCH] nfsd: destroy percpu stats counters after reply cache #5.11.0-rc5

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, May 28, 2022 at 01:41:51PM +0000, Schroeder, Julian wrote:
> >> From: Julian Schroeder <jumaco@amazon.com>
> >> Date: Fri, 20 May 2022 18:33:27 +0000
> >> Subject: [PATCH] nfsd: destroy percpu stats counters after reply cache
> >>  shutdown
> >> MIME-Version: 1.0
> >> Content-Type: text/plain; charset=UTF-8
> >> Content-Transfer-Encoding: 8bit
> >> Upon nfsd shutdown any pending DRC cache is freed. DRC cache use is
> >> tracked via a percpu counter. In the current code the percpu counter
> >> is destroyed before. If any pending cache is still present,
> >> percpu_counter_add is called with a percpu counter==NULL. This causes
> >> a kernel crash.
> >> The solution is to destroy the percpu counter after the cache is freed.
> >> Fixes: e567b98ce9a4b (âEURoenfsd: protect concurrent access to nfsd stats countersâEUR)
> >> Signed-off-by: Julian Schroeder <jumaco@amazon.com>
> >> ---
> >>  fs/nfsd/nfscache.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
> >> index 0b3f12aa37ff..7da88bdc0d6c 100644
> >> --- a/fs/nfsd/nfscache.c
> >> +++ b/fs/nfsd/nfscache.c
> >> @@ -206,7 +206,6 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
> >>         struct svc_cacherep     *rp;
> >>         unsigned int i;
> >>
> >> -       nfsd_reply_cache_stats_destroy(nn);
> >>         unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
> >>
> >>         for (i = 0; i < nn->drc_hashsize; i++) {
> >> @@ -217,6 +216,7 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
> >>                                                                         rp, nn);
> >>                 }
> >>         }
> >> +       nfsd_reply_cache_stats_destroy(nn);
> >>
> >>         kvfree(nn->drc_hashtbl);
> >>         nn->drc_hashtbl = NULL;
> >> --
> >> 2.32.0
> >>
> 
> >What is the git commit id of this in Linus's tree?
> 
> >And this patch is totally damaged with whitespace and can not be applied
> >at all :(
> 
> >Please fix it up and submit it again.
> 
> >thanks,
> 
> >greg k-h
> 
> The patch made it into linux next. commit fd5e363eac77e.
> I sent the patch to stable again via git send-email (https://www.spinics.net/lists/stable/msg560818.html)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>