From: Anna Schumaker <anna@kernel.org>
To: linux-nfs@vger.kernel.org, trond.myklebust@hammerspace.com
Cc: anna@kernel.org
Subject: [PATCH 4/4] SUNRPC: Fix a suspicious RCU usage warning
Date: Fri, 1 Dec 2023 16:15:49 -0500 [thread overview]
Message-ID: <20231201211549.126941-5-anna@kernel.org> (raw)
In-Reply-To: <20231201211549.126941-1-anna@kernel.org>
From: Anna Schumaker <Anna.Schumaker@Netapp.com>
I received the following warning while running cthon against an ontap
server running pNFS:
[ 57.202521] =============================
[ 57.202522] WARNING: suspicious RCU usage
[ 57.202523] 6.7.0-rc3-g2cc14f52aeb7 #41492 Not tainted
[ 57.202525] -----------------------------
[ 57.202525] net/sunrpc/xprtmultipath.c:349 RCU-list traversed in non-reader section!!
[ 57.202527]
other info that might help us debug this:
[ 57.202528]
rcu_scheduler_active = 2, debug_locks = 1
[ 57.202529] no locks held by test5/3567.
[ 57.202530]
stack backtrace:
[ 57.202532] CPU: 0 PID: 3567 Comm: test5 Not tainted 6.7.0-rc3-g2cc14f52aeb7 #41492 5b09971b4965c0aceba19f3eea324a4a806e227e
[ 57.202534] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 2/2/2022
[ 57.202536] Call Trace:
[ 57.202537] <TASK>
[ 57.202540] dump_stack_lvl+0x77/0xb0
[ 57.202551] lockdep_rcu_suspicious+0x154/0x1a0
[ 57.202556] rpc_xprt_switch_has_addr+0x17c/0x190 [sunrpc ebe02571b9a8ceebf7d98e71675af20c19bdb1f6]
[ 57.202596] rpc_clnt_setup_test_and_add_xprt+0x50/0x180 [sunrpc ebe02571b9a8ceebf7d98e71675af20c19bdb1f6]
[ 57.202621] ? rpc_clnt_add_xprt+0x254/0x300 [sunrpc ebe02571b9a8ceebf7d98e71675af20c19bdb1f6]
[ 57.202646] rpc_clnt_add_xprt+0x27a/0x300 [sunrpc ebe02571b9a8ceebf7d98e71675af20c19bdb1f6]
[ 57.202671] ? __pfx_rpc_clnt_setup_test_and_add_xprt+0x10/0x10 [sunrpc ebe02571b9a8ceebf7d98e71675af20c19bdb1f6]
[ 57.202696] nfs4_pnfs_ds_connect+0x345/0x760 [nfsv4 c716d88496ded0ea6d289bbea684fa996f9b57a9]
[ 57.202728] ? __pfx_nfs4_test_session_trunk+0x10/0x10 [nfsv4 c716d88496ded0ea6d289bbea684fa996f9b57a9]
[ 57.202754] nfs4_fl_prepare_ds+0x75/0xc0 [nfs_layout_nfsv41_files e3a4187f18ae8a27b630f9feae6831b584a9360a]
[ 57.202760] filelayout_write_pagelist+0x4a/0x200 [nfs_layout_nfsv41_files e3a4187f18ae8a27b630f9feae6831b584a9360a]
[ 57.202765] pnfs_generic_pg_writepages+0xbe/0x230 [nfsv4 c716d88496ded0ea6d289bbea684fa996f9b57a9]
[ 57.202788] __nfs_pageio_add_request+0x3fd/0x520 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202813] nfs_pageio_add_request+0x18b/0x390 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202831] nfs_do_writepage+0x116/0x1e0 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202849] nfs_writepages_callback+0x13/0x30 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202866] write_cache_pages+0x265/0x450
[ 57.202870] ? __pfx_nfs_writepages_callback+0x10/0x10 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202891] nfs_writepages+0x141/0x230 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202913] do_writepages+0xd2/0x230
[ 57.202917] ? filemap_fdatawrite_wbc+0x5c/0x80
[ 57.202921] filemap_fdatawrite_wbc+0x67/0x80
[ 57.202924] filemap_write_and_wait_range+0xd9/0x170
[ 57.202930] nfs_wb_all+0x49/0x180 [nfs 6c976fa593a7c2976f5a0aeb4965514a828e6902]
[ 57.202947] nfs4_file_flush+0x72/0xb0 [nfsv4 c716d88496ded0ea6d289bbea684fa996f9b57a9]
[ 57.202969] __se_sys_close+0x46/0xd0
[ 57.202972] do_syscall_64+0x68/0x100
[ 57.202975] ? do_syscall_64+0x77/0x100
[ 57.202976] ? do_syscall_64+0x77/0x100
[ 57.202979] entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ 57.202982] RIP: 0033:0x7fe2b12e4a94
[ 57.202985] Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 80 3d d5 18 0e 00 00 74 13 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 44 c3 0f 1f 00 48 83 ec 18 89 7c 24 0c e8 c3
[ 57.202987] RSP: 002b:00007ffe857ddb38 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
[ 57.202989] RAX: ffffffffffffffda RBX: 00007ffe857dfd68 RCX: 00007fe2b12e4a94
[ 57.202991] RDX: 0000000000002000 RSI: 00007ffe857ddc40 RDI: 0000000000000003
[ 57.202992] RBP: 00007ffe857dfc50 R08: 7fffffffffffffff R09: 0000000065650f49
[ 57.202993] R10: 00007fe2b11f8300 R11: 0000000000000202 R12: 0000000000000000
[ 57.202994] R13: 00007ffe857dfd80 R14: 00007fe2b1445000 R15: 0000000000000000
[ 57.202999] </TASK>
The problem seems to be that two out of three callers aren't taking the
rcu_read_lock() before calling the list_for_each_entry_rcu() function in
rpc_xprt_switch_has_addr(). I fix this by making a new variant of the
function that takes the lock when necessary, and provide a bypass path
for the one function that was doing this already.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
include/linux/sunrpc/xprtmultipath.h | 2 ++
net/sunrpc/clnt.c | 2 +-
net/sunrpc/xprtmultipath.c | 14 +++++++++++++-
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/include/linux/sunrpc/xprtmultipath.h b/include/linux/sunrpc/xprtmultipath.h
index c0514c684b2c..0598552e7ccc 100644
--- a/include/linux/sunrpc/xprtmultipath.h
+++ b/include/linux/sunrpc/xprtmultipath.h
@@ -78,6 +78,8 @@ extern struct rpc_xprt *xprt_iter_xprt(struct rpc_xprt_iter *xpi);
extern struct rpc_xprt *xprt_iter_get_xprt(struct rpc_xprt_iter *xpi);
extern struct rpc_xprt *xprt_iter_get_next(struct rpc_xprt_iter *xpi);
+extern bool __rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
+ const struct sockaddr *sap);
extern bool rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
const struct sockaddr *sap);
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 0b2c4b5484f5..b2a81c26da32 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -3299,7 +3299,7 @@ bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
rcu_read_lock();
xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
- ret = rpc_xprt_switch_has_addr(xps, sap);
+ ret = __rpc_xprt_switch_has_addr(xps, sap);
rcu_read_unlock();
return ret;
}
diff --git a/net/sunrpc/xprtmultipath.c b/net/sunrpc/xprtmultipath.c
index 701250b305db..20f9dc220383 100644
--- a/net/sunrpc/xprtmultipath.c
+++ b/net/sunrpc/xprtmultipath.c
@@ -336,7 +336,7 @@ struct rpc_xprt *xprt_iter_current_entry_offline(struct rpc_xprt_iter *xpi)
xprt_switch_find_current_entry_offline);
}
-bool rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
+bool __rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
const struct sockaddr *sap)
{
struct list_head *head;
@@ -356,6 +356,18 @@ bool rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
return false;
}
+bool rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
+ const struct sockaddr *sap)
+{
+ bool res;
+
+ rcu_read_lock();
+ res = __rpc_xprt_switch_has_addr(xps, sap);
+ rcu_read_unlock();
+
+ return res;
+}
+
static
struct rpc_xprt *xprt_switch_find_next_entry(struct list_head *head,
const struct rpc_xprt *cur, bool check_active)
--
2.43.0
next prev parent reply other threads:[~2023-12-01 21:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-01 21:15 [PATCH 0/4] SUNRPC: Various RCU fixes Anna Schumaker
2023-12-01 21:15 ` [PATCH 1/4] SUNRPC: Clean up unused variable in rpc_xprt_probe_trunked() Anna Schumaker
2023-12-03 12:18 ` Jeff Layton
2023-12-01 21:15 ` [PATCH 2/4] SUNRPC: Remove unused function rpc_clnt_xprt_switch_put() Anna Schumaker
2023-12-03 12:19 ` Jeff Layton
2023-12-01 21:15 ` [PATCH 3/4] SUNRPC: Create a helper function for accessing the rpc_clnt's xprt_switch Anna Schumaker
2023-12-03 12:24 ` Jeff Layton
2023-12-01 21:15 ` Anna Schumaker [this message]
2023-12-03 12:30 ` [PATCH 4/4] SUNRPC: Fix a suspicious RCU usage warning Jeff Layton
2023-12-04 17:00 ` Anna Schumaker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231201211549.126941-5-anna@kernel.org \
--to=anna@kernel.org \
--cc=linux-nfs@vger.kernel.org \
--cc=trond.myklebust@hammerspace.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.