From nobody Mon Feb 9 05:52:45 2026 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 13C17EB64DC for ; Fri, 16 Jun 2023 19:21:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346225AbjFPTVl (ORCPT ); Fri, 16 Jun 2023 15:21:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231154AbjFPTVW (ORCPT ); Fri, 16 Jun 2023 15:21:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CF32524A; Fri, 16 Jun 2023 12:19:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 99902634BF; Fri, 16 Jun 2023 19:17:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 382D2C433C8; Fri, 16 Jun 2023 19:17:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686943067; bh=CAmP+Lx0wzqgHUs9vsC25lJNjq99NNhM1Mo48RueGyc=; h=From:To:Cc:Subject:Date:From; b=ZETvxHndWQKmZsWWEKvvXIR1NvhG0E+JQ9XMa5/v0HqoF1ZdzNxZ/GXDMO1LaUO4z dTo8UADnCGD6UZuvo5lDy70OAvdWz0SEcdnue4m1STiOYVAY/m8pN9g8X7LsAjmFCV zok7BR7RRfuq5+ikc05b+FO7Rmn7O0Pbe+upHOn3mYLkVA10AGC4zNbpMXNNioCN16 1PTOFhDX5zn5YaV8YcoVZgp0uT2FEmQOco1kT6lgBXkuDqdNO3Mnf7uVEjoZB0QGZs qujzgPiXMdTyhI6XZL1nnpWuTmGkiAdXp5cymmX88O+lp0TYmei3kIU55NqFC4tDn4 VeQ7NL4ofgUqw== From: Jeff Layton To: Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: stable@vger.kernel.org, Eirik Fuller , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net Date: Fri, 16 Jun 2023 15:17:43 -0400 Message-Id: <20230616191744.202292-1-jlayton@kernel.org> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" f5f9d4a314da moved the initialization of the reply cache into the nfsd startup, but it didn't account for the stats counters which can be accessed before nfsd is ever started, causing a NULL pointer dereference. This is easy to trigger on some arches (like aarch64), but on x86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the fixed_percpu_data, which I guess this looks just enough like a newly initialized percpu var to allow nfsd_reply_cache_stats_show to access it without Oopsing. Move the initialization of the per-net+per-cpu reply-cache counters back into nfsd_init_net, while leaving the rest of the reply cache allocations to be done at nfsd startup time. Kudos to Eirik who did most of the legwork to track this down. Cc: stable@vger.kernel.org # v6.3+ Fixes: f5f9d4a314da ("nfsd: move reply cache initialization into nfsd start= up") Reported-and-Tested-by: Eirik Fuller Signed-off-by: Jeff Layton --- fs/nfsd/cache.h | 2 ++ fs/nfsd/nfscache.c | 13 +++---------- fs/nfsd/nfsctl.c | 8 ++++++++ 3 files changed, 13 insertions(+), 10 deletions(-) diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h index f21259ead64b..a4b12d6c41d3 100644 --- a/fs/nfsd/cache.h +++ b/fs/nfsd/cache.h @@ -80,6 +80,8 @@ enum { =20 int nfsd_drc_slab_create(void); void nfsd_drc_slab_free(void); +int nfsd_reply_cache_stats_init(struct nfsd_net *nn); +void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn); int nfsd_reply_cache_init(struct nfsd_net *); void nfsd_reply_cache_shutdown(struct nfsd_net *); int nfsd_cache_lookup(struct svc_rqst *); diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 041faa13b852..b696dc629c0b 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -148,12 +148,12 @@ void nfsd_drc_slab_free(void) kmem_cache_destroy(drc_slab); } =20 -static int nfsd_reply_cache_stats_init(struct nfsd_net *nn) +int nfsd_reply_cache_stats_init(struct nfsd_net *nn) { return nfsd_percpu_counters_init(nn->counter, NFSD_NET_COUNTERS_NUM); } =20 -static void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn) +void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn) { nfsd_percpu_counters_destroy(nn->counter, NFSD_NET_COUNTERS_NUM); } @@ -169,17 +169,13 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) hashsize =3D nfsd_hashsize(nn->max_drc_entries); nn->maskbits =3D ilog2(hashsize); =20 - status =3D nfsd_reply_cache_stats_init(nn); - if (status) - goto out_nomem; - nn->nfsd_reply_cache_shrinker.scan_objects =3D nfsd_reply_cache_scan; nn->nfsd_reply_cache_shrinker.count_objects =3D nfsd_reply_cache_count; nn->nfsd_reply_cache_shrinker.seeks =3D 1; status =3D register_shrinker(&nn->nfsd_reply_cache_shrinker, "nfsd-reply:%s", nn->nfsd_name); if (status) - goto out_stats_destroy; + return status; =20 nn->drc_hashtbl =3D kvzalloc(array_size(hashsize, sizeof(*nn->drc_hashtbl)), GFP_KERNEL); @@ -195,9 +191,6 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) return 0; out_shrinker: unregister_shrinker(&nn->nfsd_reply_cache_shrinker); -out_stats_destroy: - nfsd_reply_cache_stats_destroy(nn); -out_nomem: printk(KERN_ERR "nfsd: failed to allocate reply cache\n"); return -ENOMEM; } diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 1489e0b703b4..7c837afcf615 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1505,6 +1505,9 @@ static __net_init int nfsd_init_net(struct net *net) retval =3D nfsd_idmap_init(net); if (retval) goto out_idmap_error; + retval =3D nfsd_reply_cache_stats_init(nn); + if (retval) + goto out_repcache_error; nn->nfsd_versions =3D NULL; nn->nfsd4_minorversions =3D NULL; nfsd4_init_leases_net(nn); @@ -1513,6 +1516,8 @@ static __net_init int nfsd_init_net(struct net *net) =20 return 0; =20 +out_repcache_error: + nfsd_idmap_shutdown(net); out_idmap_error: nfsd_export_shutdown(net); out_export_error: @@ -1521,6 +1526,9 @@ static __net_init int nfsd_init_net(struct net *net) =20 static __net_exit void nfsd_exit_net(struct net *net) { + struct nfsd_net *nn =3D net_generic(net, nfsd_net_id); + + nfsd_reply_cache_stats_destroy(nn); nfsd_idmap_shutdown(net); nfsd_export_shutdown(net); nfsd_netns_free_versions(net_generic(net, nfsd_net_id)); --=20 2.40.1