* [Linux-kernel-mentees] [PATCH] ext4: use rcu API in debug_print_tree
@ 2019-12-01 3:51 Phong Tran
2019-12-13 11:35 ` Jan Kara
0 siblings, 1 reply; 7+ messages in thread
From: Phong Tran @ 2019-12-01 3:51 UTC (permalink / raw)
To: tytso, adilger.kernel, paulmck, joel
Cc: rcu, linux-ext4, linux-kernel-mentees, linux-kernel
struct ext4_sb_info.system_blks was marked __rcu.
But access the pointer without using RCU lock and dereference.
Sparse warning with __rcu notation:
block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
block_validity.c:139:29: expected struct rb_root const *
block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
Signed-off-by: Phong Tran <tranmanphong@gmail.com>
---
fs/ext4/block_validity.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index d4d4fdfac1a6..1ee04e76bbe0 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -133,10 +133,13 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
{
struct rb_node *node;
struct ext4_system_zone *entry;
+ struct ext4_system_blocks *system_blks;
int first = 1;
printk(KERN_INFO "System zones: ");
- node = rb_first(&sbi->system_blks->root);
+ rcu_read_lock();
+ system_blks = rcu_dereference(sbi->system_blks);
+ node = rb_first(&system_blks->root);
while (node) {
entry = rb_entry(node, struct ext4_system_zone, node);
printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
@@ -144,6 +147,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
first = 0;
node = rb_next(node);
}
+ rcu_read_unlock();
printk(KERN_CONT "\n");
}
--
2.20.1
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^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] ext4: use rcu API in debug_print_tree
2019-12-01 3:51 [Linux-kernel-mentees] [PATCH] ext4: use rcu API in debug_print_tree Phong Tran
@ 2019-12-13 11:35 ` Jan Kara
2019-12-13 15:33 ` [Linux-kernel-mentees] [PATCH V2] " Phong Tran
0 siblings, 1 reply; 7+ messages in thread
From: Jan Kara @ 2019-12-13 11:35 UTC (permalink / raw)
To: Phong Tran
Cc: tytso, paulmck, linux-kernel, rcu, adilger.kernel, joel,
linux-ext4, linux-kernel-mentees
On Sun 01-12-19 10:51:07, Phong Tran wrote:
> struct ext4_sb_info.system_blks was marked __rcu.
> But access the pointer without using RCU lock and dereference.
> Sparse warning with __rcu notation:
>
> block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
> block_validity.c:139:29: expected struct rb_root const *
> block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
>
> Signed-off-by: Phong Tran <tranmanphong@gmail.com>
Thanks for the patch. It looks good to me. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> ---
> fs/ext4/block_validity.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
> index d4d4fdfac1a6..1ee04e76bbe0 100644
> --- a/fs/ext4/block_validity.c
> +++ b/fs/ext4/block_validity.c
> @@ -133,10 +133,13 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> {
> struct rb_node *node;
> struct ext4_system_zone *entry;
> + struct ext4_system_blocks *system_blks;
> int first = 1;
>
> printk(KERN_INFO "System zones: ");
> - node = rb_first(&sbi->system_blks->root);
> + rcu_read_lock();
> + system_blks = rcu_dereference(sbi->system_blks);
> + node = rb_first(&system_blks->root);
> while (node) {
> entry = rb_entry(node, struct ext4_system_zone, node);
> printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
> @@ -144,6 +147,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> first = 0;
> node = rb_next(node);
> }
> + rcu_read_unlock();
> printk(KERN_CONT "\n");
> }
>
> --
> 2.20.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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^ permalink raw reply [flat|nested] 7+ messages in thread
* [Linux-kernel-mentees] [PATCH V2] ext4: use rcu API in debug_print_tree
2019-12-13 11:35 ` Jan Kara
@ 2019-12-13 15:33 ` Phong Tran
2019-12-13 18:11 ` Joel Fernandes
2019-12-16 2:41 ` Theodore Y. Ts'o
0 siblings, 2 replies; 7+ messages in thread
From: Phong Tran @ 2019-12-13 15:33 UTC (permalink / raw)
To: jack, tytso, adilger.kernel
Cc: paulmck, linux-kernel, rcu, joel, linux-ext4, linux-kernel-mentees
struct ext4_sb_info.system_blks was marked __rcu.
But access the pointer without using RCU lock and dereference.
Sparse warning with __rcu notation:
block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
block_validity.c:139:29: expected struct rb_root const *
block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Phong Tran <tranmanphong@gmail.com>
---
fs/ext4/block_validity.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
---
change log:
V2: Add Reviewed-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index d4d4fdfac1a6..1ee04e76bbe0 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -133,10 +133,13 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
{
struct rb_node *node;
struct ext4_system_zone *entry;
+ struct ext4_system_blocks *system_blks;
int first = 1;
printk(KERN_INFO "System zones: ");
- node = rb_first(&sbi->system_blks->root);
+ rcu_read_lock();
+ system_blks = rcu_dereference(sbi->system_blks);
+ node = rb_first(&system_blks->root);
while (node) {
entry = rb_entry(node, struct ext4_system_zone, node);
printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
@@ -144,6 +147,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
first = 0;
node = rb_next(node);
}
+ rcu_read_unlock();
printk(KERN_CONT "\n");
}
--
2.20.1
_______________________________________________
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Linux-kernel-mentees@lists.linuxfoundation.org
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^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH V2] ext4: use rcu API in debug_print_tree
2019-12-13 15:33 ` [Linux-kernel-mentees] [PATCH V2] " Phong Tran
@ 2019-12-13 18:11 ` Joel Fernandes
2019-12-13 19:49 ` Jan Kara
2019-12-16 2:41 ` Theodore Y. Ts'o
1 sibling, 1 reply; 7+ messages in thread
From: Joel Fernandes @ 2019-12-13 18:11 UTC (permalink / raw)
To: Phong Tran
Cc: Theodore Y. Ts'o, Paul E. McKenney, LKML, stable, rcu,
adilger.kernel, Jan Kara, linux-ext4, linux-kernel-mentees
On Fri, Dec 13, 2019 at 7:39 AM Phong Tran <tranmanphong@gmail.com> wrote:
>
> struct ext4_sb_info.system_blks was marked __rcu.
> But access the pointer without using RCU lock and dereference.
> Sparse warning with __rcu notation:
>
> block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
> block_validity.c:139:29: expected struct rb_root const *
> block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Phong Tran <tranmanphong@gmail.com>
Thanks Phong! Looks like a real bug fix caught thanks to Sparse. So
let us mark for stable as well?
- Joel
> ---
> fs/ext4/block_validity.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> ---
> change log:
> V2: Add Reviewed-by: Jan Kara <jack@suse.cz>
>
> diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
> index d4d4fdfac1a6..1ee04e76bbe0 100644
> --- a/fs/ext4/block_validity.c
> +++ b/fs/ext4/block_validity.c
> @@ -133,10 +133,13 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> {
> struct rb_node *node;
> struct ext4_system_zone *entry;
> + struct ext4_system_blocks *system_blks;
> int first = 1;
>
> printk(KERN_INFO "System zones: ");
> - node = rb_first(&sbi->system_blks->root);
> + rcu_read_lock();
> + system_blks = rcu_dereference(sbi->system_blks);
> + node = rb_first(&system_blks->root);
> while (node) {
> entry = rb_entry(node, struct ext4_system_zone, node);
> printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
> @@ -144,6 +147,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> first = 0;
> node = rb_next(node);
> }
> + rcu_read_unlock();
> printk(KERN_CONT "\n");
> }
>
> --
> 2.20.1
>
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https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH V2] ext4: use rcu API in debug_print_tree
2019-12-13 18:11 ` Joel Fernandes
@ 2019-12-13 19:49 ` Jan Kara
2019-12-13 23:19 ` Joel Fernandes
0 siblings, 1 reply; 7+ messages in thread
From: Jan Kara @ 2019-12-13 19:49 UTC (permalink / raw)
To: Joel Fernandes
Cc: Theodore Y. Ts'o, Paul E. McKenney, LKML, stable, rcu,
adilger.kernel, Jan Kara, linux-ext4, linux-kernel-mentees
On Fri 13-12-19 10:11:50, Joel Fernandes wrote:
> On Fri, Dec 13, 2019 at 7:39 AM Phong Tran <tranmanphong@gmail.com> wrote:
> >
> > struct ext4_sb_info.system_blks was marked __rcu.
> > But access the pointer without using RCU lock and dereference.
> > Sparse warning with __rcu notation:
> >
> > block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
> > block_validity.c:139:29: expected struct rb_root const *
> > block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
> >
> > Reviewed-by: Jan Kara <jack@suse.cz>
> > Signed-off-by: Phong Tran <tranmanphong@gmail.com>
>
> Thanks Phong! Looks like a real bug fix caught thanks to Sparse. So
> let us mark for stable as well?
Well, not really. The code is active only with CONFIG_EXT4_DEBUG enabled
and in this case there's no race with remount (and thus sbi->system_blks
changing) possible. So the change is really only to silence the sparse
warning.
Honza
>
> - Joel
>
> > ---
> > fs/ext4/block_validity.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > ---
> > change log:
> > V2: Add Reviewed-by: Jan Kara <jack@suse.cz>
> >
> > diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
> > index d4d4fdfac1a6..1ee04e76bbe0 100644
> > --- a/fs/ext4/block_validity.c
> > +++ b/fs/ext4/block_validity.c
> > @@ -133,10 +133,13 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> > {
> > struct rb_node *node;
> > struct ext4_system_zone *entry;
> > + struct ext4_system_blocks *system_blks;
> > int first = 1;
> >
> > printk(KERN_INFO "System zones: ");
> > - node = rb_first(&sbi->system_blks->root);
> > + rcu_read_lock();
> > + system_blks = rcu_dereference(sbi->system_blks);
> > + node = rb_first(&system_blks->root);
> > while (node) {
> > entry = rb_entry(node, struct ext4_system_zone, node);
> > printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
> > @@ -144,6 +147,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> > first = 0;
> > node = rb_next(node);
> > }
> > + rcu_read_unlock();
> > printk(KERN_CONT "\n");
> > }
> >
> > --
> > 2.20.1
> >
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
_______________________________________________
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] 7+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH V2] ext4: use rcu API in debug_print_tree
2019-12-13 19:49 ` Jan Kara
@ 2019-12-13 23:19 ` Joel Fernandes
0 siblings, 0 replies; 7+ messages in thread
From: Joel Fernandes @ 2019-12-13 23:19 UTC (permalink / raw)
To: Jan Kara
Cc: Theodore Y. Ts'o, Paul E. McKenney, LKML, stable, rcu,
adilger.kernel, linux-ext4, linux-kernel-mentees
On Fri, Dec 13, 2019 at 08:49:43PM +0100, Jan Kara wrote:
> On Fri 13-12-19 10:11:50, Joel Fernandes wrote:
> > On Fri, Dec 13, 2019 at 7:39 AM Phong Tran <tranmanphong@gmail.com> wrote:
> > >
> > > struct ext4_sb_info.system_blks was marked __rcu.
> > > But access the pointer without using RCU lock and dereference.
> > > Sparse warning with __rcu notation:
> > >
> > > block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
> > > block_validity.c:139:29: expected struct rb_root const *
> > > block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
> > >
> > > Reviewed-by: Jan Kara <jack@suse.cz>
> > > Signed-off-by: Phong Tran <tranmanphong@gmail.com>
> >
> > Thanks Phong! Looks like a real bug fix caught thanks to Sparse. So
> > let us mark for stable as well?
>
> Well, not really. The code is active only with CONFIG_EXT4_DEBUG enabled
> and in this case there's no race with remount (and thus sbi->system_blks
> changing) possible. So the change is really only to silence the sparse
> warning.
Ok, thanks for clarifying.
-Joel
>
> Honza
>
> >
> > - Joel
> >
> > > ---
> > > fs/ext4/block_validity.c | 6 +++++-
> > > 1 file changed, 5 insertions(+), 1 deletion(-)
> > >
> > > ---
> > > change log:
> > > V2: Add Reviewed-by: Jan Kara <jack@suse.cz>
> > >
> > > diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
> > > index d4d4fdfac1a6..1ee04e76bbe0 100644
> > > --- a/fs/ext4/block_validity.c
> > > +++ b/fs/ext4/block_validity.c
> > > @@ -133,10 +133,13 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> > > {
> > > struct rb_node *node;
> > > struct ext4_system_zone *entry;
> > > + struct ext4_system_blocks *system_blks;
> > > int first = 1;
> > >
> > > printk(KERN_INFO "System zones: ");
> > > - node = rb_first(&sbi->system_blks->root);
> > > + rcu_read_lock();
> > > + system_blks = rcu_dereference(sbi->system_blks);
> > > + node = rb_first(&system_blks->root);
> > > while (node) {
> > > entry = rb_entry(node, struct ext4_system_zone, node);
> > > printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
> > > @@ -144,6 +147,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
> > > first = 0;
> > > node = rb_next(node);
> > > }
> > > + rcu_read_unlock();
> > > printk(KERN_CONT "\n");
> > > }
> > >
> > > --
> > > 2.20.1
> > >
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
_______________________________________________
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH V2] ext4: use rcu API in debug_print_tree
2019-12-13 15:33 ` [Linux-kernel-mentees] [PATCH V2] " Phong Tran
2019-12-13 18:11 ` Joel Fernandes
@ 2019-12-16 2:41 ` Theodore Y. Ts'o
1 sibling, 0 replies; 7+ messages in thread
From: Theodore Y. Ts'o @ 2019-12-16 2:41 UTC (permalink / raw)
To: Phong Tran
Cc: jack, paulmck, linux-kernel, rcu, adilger.kernel, joel,
linux-ext4, linux-kernel-mentees
On Fri, Dec 13, 2019 at 10:33:07PM +0700, Phong Tran wrote:
> struct ext4_sb_info.system_blks was marked __rcu.
> But access the pointer without using RCU lock and dereference.
> Sparse warning with __rcu notation:
>
> block_validity.c:139:29: warning: incorrect type in argument 1 (different address spaces)
> block_validity.c:139:29: expected struct rb_root const *
> block_validity.c:139:29: got struct rb_root [noderef] <asn:4> *
>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Phong Tran <tranmanphong@gmail.com>
Applied, thanks.
- Ted
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^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-12-16 2:42 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-12-01 3:51 [Linux-kernel-mentees] [PATCH] ext4: use rcu API in debug_print_tree Phong Tran
2019-12-13 11:35 ` Jan Kara
2019-12-13 15:33 ` [Linux-kernel-mentees] [PATCH V2] " Phong Tran
2019-12-13 18:11 ` Joel Fernandes
2019-12-13 19:49 ` Jan Kara
2019-12-13 23:19 ` Joel Fernandes
2019-12-16 2:41 ` Theodore Y. Ts'o
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