* [Linux-kernel-mentees] [PATCH net v2 1/2] ipmr: Fix RCU list debugging warning
@ 2020-05-14 18:01 ` Amol Grover
0 siblings, 0 replies; 8+ messages in thread
From: Amol Grover @ 2020-05-14 18:01 UTC (permalink / raw)
To: David S . Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI,
Jakub Kicinski, Patrick McHardy, Stephen Rothwell, Qian Cai
Cc: Paul E . McKenney, netdev, linux-kernel, Madhuparna Bhowmik,
Joel Fernandes, linux-kernel-mentees
ipmr_for_each_table() macro uses list_for_each_entry_rcu()
for traversing outside of an RCU read side critical section
but under the protection of rtnl_mutex. Hence, add the
corresponding lockdep expression to silence the following
false-positive warning at boot:
[ 4.319347] =============================
[ 4.319349] WARNING: suspicious RCU usage
[ 4.319351] 5.5.4-stable #17 Tainted: G E
[ 4.319352] -----------------------------
[ 4.319354] net/ipv4/ipmr.c:1757 RCU-list traversed in non-reader section!!
Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v2:
- Add appropriate Fixes tag
net/ipv4/ipmr.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 9cf83cc85e4a..4897f7420c8f 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -110,7 +110,8 @@ static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list)
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held())
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1
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^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH net v2 1/2] ipmr: Fix RCU list debugging warning
@ 2020-05-14 18:01 ` Amol Grover
0 siblings, 0 replies; 8+ messages in thread
From: Amol Grover @ 2020-05-14 18:01 UTC (permalink / raw)
To: David S . Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI,
Jakub Kicinski, Patrick McHardy, Stephen Rothwell, Qian Cai
Cc: netdev, linux-kernel, linux-kernel-mentees, Joel Fernandes,
Madhuparna Bhowmik, Paul E . McKenney, Amol Grover
ipmr_for_each_table() macro uses list_for_each_entry_rcu()
for traversing outside of an RCU read side critical section
but under the protection of rtnl_mutex. Hence, add the
corresponding lockdep expression to silence the following
false-positive warning at boot:
[ 4.319347] =============================
[ 4.319349] WARNING: suspicious RCU usage
[ 4.319351] 5.5.4-stable #17 Tainted: G E
[ 4.319352] -----------------------------
[ 4.319354] net/ipv4/ipmr.c:1757 RCU-list traversed in non-reader section!!
Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v2:
- Add appropriate Fixes tag
net/ipv4/ipmr.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 9cf83cc85e4a..4897f7420c8f 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -110,7 +110,8 @@ static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list)
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held())
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* [Linux-kernel-mentees] [PATCH net v2 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro
2020-05-14 18:01 ` Amol Grover
@ 2020-05-14 18:01 ` Amol Grover
-1 siblings, 0 replies; 8+ messages in thread
From: Amol Grover @ 2020-05-14 18:01 UTC (permalink / raw)
To: David S . Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI,
Jakub Kicinski, Patrick McHardy, Stephen Rothwell, Qian Cai
Cc: Paul E . McKenney, netdev, syzbot+1519f497f2f9f08183c6,
linux-kernel, Madhuparna Bhowmik, Joel Fernandes,
linux-kernel-mentees
During the initialization process, ipmr_new_table() is called
to create new tables which in turn calls ipmr_get_table() which
traverses net->ipv4.mr_tables without holding the writer lock.
However, this is safe to do so as no tables exist at this time.
Hence add a suitable lockdep expression to silence the following
false-positive warning:
=============================
WARNING: suspicious RCU usage
5.7.0-rc3-next-20200428-syzkaller #0 Not tainted
-----------------------------
net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!
ipmr_get_table+0x130/0x160 net/ipv4/ipmr.c:136
ipmr_new_table net/ipv4/ipmr.c:403 [inline]
ipmr_rules_init net/ipv4/ipmr.c:248 [inline]
ipmr_net_init+0x133/0x430 net/ipv4/ipmr.c:3089
Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
Reported-by: syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v2:
- Change the lockdep expression to check for list emptiness at init
- Add Fixes tag
- Add Reported-by tag for syzbot report
net/ipv4/ipmr.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 4897f7420c8f..5c218db2dede 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
- lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net) \
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held() || \
+ list_empty(&net->ipv4.mr_tables))
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH net v2 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro
@ 2020-05-14 18:01 ` Amol Grover
0 siblings, 0 replies; 8+ messages in thread
From: Amol Grover @ 2020-05-14 18:01 UTC (permalink / raw)
To: David S . Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI,
Jakub Kicinski, Patrick McHardy, Stephen Rothwell, Qian Cai
Cc: netdev, linux-kernel, linux-kernel-mentees, Joel Fernandes,
Madhuparna Bhowmik, Paul E . McKenney, Amol Grover,
syzbot+1519f497f2f9f08183c6
During the initialization process, ipmr_new_table() is called
to create new tables which in turn calls ipmr_get_table() which
traverses net->ipv4.mr_tables without holding the writer lock.
However, this is safe to do so as no tables exist at this time.
Hence add a suitable lockdep expression to silence the following
false-positive warning:
=============================
WARNING: suspicious RCU usage
5.7.0-rc3-next-20200428-syzkaller #0 Not tainted
-----------------------------
net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!
ipmr_get_table+0x130/0x160 net/ipv4/ipmr.c:136
ipmr_new_table net/ipv4/ipmr.c:403 [inline]
ipmr_rules_init net/ipv4/ipmr.c:248 [inline]
ipmr_net_init+0x133/0x430 net/ipv4/ipmr.c:3089
Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
Reported-by: syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v2:
- Change the lockdep expression to check for list emptiness at init
- Add Fixes tag
- Add Reported-by tag for syzbot report
net/ipv4/ipmr.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 4897f7420c8f..5c218db2dede 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
- lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net) \
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held() || \
+ list_empty(&net->ipv4.mr_tables))
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [Linux-kernel-mentees] [PATCH net v2 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro
2020-05-14 18:01 ` Amol Grover
@ 2020-05-15 1:01 ` David Miller
-1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2020-05-15 1:01 UTC (permalink / raw)
To: frextrite
Cc: sfr, paulmck, syzbot+1519f497f2f9f08183c6, yoshfuji, netdev,
linux-kernel, madhuparnabhowmik10, cai, kuba, joel, kuznet,
linux-kernel-mentees, kaber
From: Amol Grover <frextrite@gmail.com>
Date: Thu, 14 May 2020 23:31:03 +0530
> During the initialization process, ipmr_new_table() is called
> to create new tables which in turn calls ipmr_get_table() which
> traverses net->ipv4.mr_tables without holding the writer lock.
> However, this is safe to do so as no tables exist at this time.
> Hence add a suitable lockdep expression to silence the following
> false-positive warning:
>
> =============================
> WARNING: suspicious RCU usage
> 5.7.0-rc3-next-20200428-syzkaller #0 Not tainted
> -----------------------------
> net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!
>
> ipmr_get_table+0x130/0x160 net/ipv4/ipmr.c:136
> ipmr_new_table net/ipv4/ipmr.c:403 [inline]
> ipmr_rules_init net/ipv4/ipmr.c:248 [inline]
> ipmr_net_init+0x133/0x430 net/ipv4/ipmr.c:3089
>
> Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
> Reported-by: syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Amol Grover <frextrite@gmail.com>
Applied.
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net v2 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro
@ 2020-05-15 1:01 ` David Miller
0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2020-05-15 1:01 UTC (permalink / raw)
To: frextrite
Cc: kuznet, yoshfuji, kuba, kaber, sfr, cai, netdev, linux-kernel,
linux-kernel-mentees, joel, madhuparnabhowmik10, paulmck,
syzbot+1519f497f2f9f08183c6
From: Amol Grover <frextrite@gmail.com>
Date: Thu, 14 May 2020 23:31:03 +0530
> During the initialization process, ipmr_new_table() is called
> to create new tables which in turn calls ipmr_get_table() which
> traverses net->ipv4.mr_tables without holding the writer lock.
> However, this is safe to do so as no tables exist at this time.
> Hence add a suitable lockdep expression to silence the following
> false-positive warning:
>
> =============================
> WARNING: suspicious RCU usage
> 5.7.0-rc3-next-20200428-syzkaller #0 Not tainted
> -----------------------------
> net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!
>
> ipmr_get_table+0x130/0x160 net/ipv4/ipmr.c:136
> ipmr_new_table net/ipv4/ipmr.c:403 [inline]
> ipmr_rules_init net/ipv4/ipmr.c:248 [inline]
> ipmr_net_init+0x133/0x430 net/ipv4/ipmr.c:3089
>
> Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
> Reported-by: syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Amol Grover <frextrite@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH net v2 1/2] ipmr: Fix RCU list debugging warning
2020-05-14 18:01 ` Amol Grover
@ 2020-05-15 1:01 ` David Miller
-1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2020-05-15 1:01 UTC (permalink / raw)
To: frextrite
Cc: sfr, paulmck, yoshfuji, netdev, linux-kernel, madhuparnabhowmik10,
cai, kuba, joel, kuznet, linux-kernel-mentees, kaber
From: Amol Grover <frextrite@gmail.com>
Date: Thu, 14 May 2020 23:31:02 +0530
> ipmr_for_each_table() macro uses list_for_each_entry_rcu()
> for traversing outside of an RCU read side critical section
> but under the protection of rtnl_mutex. Hence, add the
> corresponding lockdep expression to silence the following
> false-positive warning at boot:
>
> [ 4.319347] =============================
> [ 4.319349] WARNING: suspicious RCU usage
> [ 4.319351] 5.5.4-stable #17 Tainted: G E
> [ 4.319352] -----------------------------
> [ 4.319354] net/ipv4/ipmr.c:1757 RCU-list traversed in non-reader section!!
>
> Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
> Signed-off-by: Amol Grover <frextrite@gmail.com>
Applied.
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net v2 1/2] ipmr: Fix RCU list debugging warning
@ 2020-05-15 1:01 ` David Miller
0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2020-05-15 1:01 UTC (permalink / raw)
To: frextrite
Cc: kuznet, yoshfuji, kuba, kaber, sfr, cai, netdev, linux-kernel,
linux-kernel-mentees, joel, madhuparnabhowmik10, paulmck
From: Amol Grover <frextrite@gmail.com>
Date: Thu, 14 May 2020 23:31:02 +0530
> ipmr_for_each_table() macro uses list_for_each_entry_rcu()
> for traversing outside of an RCU read side critical section
> but under the protection of rtnl_mutex. Hence, add the
> corresponding lockdep expression to silence the following
> false-positive warning at boot:
>
> [ 4.319347] =============================
> [ 4.319349] WARNING: suspicious RCU usage
> [ 4.319351] 5.5.4-stable #17 Tainted: G E
> [ 4.319352] -----------------------------
> [ 4.319354] net/ipv4/ipmr.c:1757 RCU-list traversed in non-reader section!!
>
> Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables")
> Signed-off-by: Amol Grover <frextrite@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-05-15 1:01 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
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2020-05-14 18:01 [Linux-kernel-mentees] [PATCH net v2 1/2] ipmr: Fix RCU list debugging warning Amol Grover
2020-05-14 18:01 ` Amol Grover
2020-05-14 18:01 ` [Linux-kernel-mentees] [PATCH net v2 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro Amol Grover
2020-05-14 18:01 ` Amol Grover
2020-05-15 1:01 ` [Linux-kernel-mentees] " David Miller
2020-05-15 1:01 ` David Miller
2020-05-15 1:01 ` [Linux-kernel-mentees] [PATCH net v2 1/2] ipmr: Fix RCU list debugging warning David Miller
2020-05-15 1:01 ` David Miller
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