noop_backing_dev_info is used by superblocks of various
pseudofilesystems such as kdevtmpfs. After commit 10e14073107d
("writeback: Fix inode->i_io_list not be protected by inode->i_lock
error") this broke because __mark_inode_dirty() started to access more
fields from noop_backing_dev_info and this led to crashes inside
locked_inode_to_wb_and_lock_list() called from __mark_inode_dirty().
Fix the problem by initializing noop_backing_dev_info before the
filesystems get mounted.
Fixes: 10e14073107d ("writeback: Fix inode->i_io_list not be protected by inode->i_lock error")
Reported-by: Suzuki K Poulose <[email protected]>
Reported-and-tested-by: Alexandru Elisei <[email protected]>
Reported-and-tested-by: Guenter Roeck <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
---
drivers/base/init.c | 2 ++
include/linux/backing-dev.h | 2 ++
mm/backing-dev.c | 11 ++---------
3 files changed, 6 insertions(+), 9 deletions(-)
Since this bug prevents some machines from booting, I plan to push this patch
to Linus unless someone objects soon... Review is welcome :).
diff --git a/drivers/base/init.c b/drivers/base/init.c
index d8d0fe687111..397eb9880cec 100644
--- a/drivers/base/init.c
+++ b/drivers/base/init.c
@@ -8,6 +8,7 @@
#include <linux/init.h>
#include <linux/memory.h>
#include <linux/of.h>
+#include <linux/backing-dev.h>
#include "base.h"
@@ -20,6 +21,7 @@
void __init driver_init(void)
{
/* These are the core pieces */
+ bdi_init(&noop_backing_dev_info);
devtmpfs_init();
devices_init();
buses_init();
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 2bd073fa6bb5..f0baef68f90f 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -119,6 +119,8 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
extern struct backing_dev_info noop_backing_dev_info;
+extern int bdi_init(struct backing_dev_info *bdi);
+
/**
* writeback_in_progress - determine whether there is writeback in progress
* @wb: bdi_writeback of interest
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index ff60bd7d74e0..95550b8fa7fe 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -231,20 +231,13 @@ static __init int bdi_class_init(void)
}
postcore_initcall(bdi_class_init);
-static int bdi_init(struct backing_dev_info *bdi);
-
static int __init default_bdi_init(void)
{
- int err;
-
bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
WQ_SYSFS, 0);
if (!bdi_wq)
return -ENOMEM;
-
- err = bdi_init(&noop_backing_dev_info);
-
- return err;
+ return 0;
}
subsys_initcall(default_bdi_init);
@@ -781,7 +774,7 @@ static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
#endif /* CONFIG_CGROUP_WRITEBACK */
-static int bdi_init(struct backing_dev_info *bdi)
+int bdi_init(struct backing_dev_info *bdi)
{
int ret;
--
2.35.3
On Wed, Jun 15, 2022 at 11:48:15PM +0200, Jan Kara wrote:
> +extern int bdi_init(struct backing_dev_info *bdi);
No need for the extern.
Otherwise looks good:
Reviewed-by: Christoph Hellwig <[email protected]>
And this remind me that I really want to kill noop_backing_dev_info
and just use a NULL bdi for this case eventually..
On 15/06/2022 22:48, Jan Kara wrote:
> noop_backing_dev_info is used by superblocks of various
> pseudofilesystems such as kdevtmpfs. After commit 10e14073107d
> ("writeback: Fix inode->i_io_list not be protected by inode->i_lock
> error") this broke because __mark_inode_dirty() started to access more
> fields from noop_backing_dev_info and this led to crashes inside
> locked_inode_to_wb_and_lock_list() called from __mark_inode_dirty().
> Fix the problem by initializing noop_backing_dev_info before the
> filesystems get mounted.
>
> Fixes: 10e14073107d ("writeback: Fix inode->i_io_list not be protected by inode->i_lock error")
> Reported-by: Suzuki K Poulose <[email protected]>
> Reported-and-tested-by: Alexandru Elisei <[email protected]>
> Reported-and-tested-by: Guenter Roeck <[email protected]>
> Signed-off-by: Jan Kara <[email protected]>
Works for me too. Thanks for the proper fix
Tested-by: Suzuki K Poulose <[email protected]>
> ---
> drivers/base/init.c | 2 ++
> include/linux/backing-dev.h | 2 ++
> mm/backing-dev.c | 11 ++---------
> 3 files changed, 6 insertions(+), 9 deletions(-)
>
> Since this bug prevents some machines from booting, I plan to push this patch
> to Linus unless someone objects soon... Review is welcome :).
>
> diff --git a/drivers/base/init.c b/drivers/base/init.c
> index d8d0fe687111..397eb9880cec 100644
> --- a/drivers/base/init.c
> +++ b/drivers/base/init.c
> @@ -8,6 +8,7 @@
> #include <linux/init.h>
> #include <linux/memory.h>
> #include <linux/of.h>
> +#include <linux/backing-dev.h>
>
> #include "base.h"
>
> @@ -20,6 +21,7 @@
> void __init driver_init(void)
> {
> /* These are the core pieces */
> + bdi_init(&noop_backing_dev_info);
> devtmpfs_init();
> devices_init();
> buses_init();
> diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
> index 2bd073fa6bb5..f0baef68f90f 100644
> --- a/include/linux/backing-dev.h
> +++ b/include/linux/backing-dev.h
> @@ -119,6 +119,8 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
>
> extern struct backing_dev_info noop_backing_dev_info;
>
> +extern int bdi_init(struct backing_dev_info *bdi);
> +
> /**
> * writeback_in_progress - determine whether there is writeback in progress
> * @wb: bdi_writeback of interest
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index ff60bd7d74e0..95550b8fa7fe 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -231,20 +231,13 @@ static __init int bdi_class_init(void)
> }
> postcore_initcall(bdi_class_init);
>
> -static int bdi_init(struct backing_dev_info *bdi);
> -
> static int __init default_bdi_init(void)
> {
> - int err;
> -
> bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
> WQ_SYSFS, 0);
> if (!bdi_wq)
> return -ENOMEM;
> -
> - err = bdi_init(&noop_backing_dev_info);
> -
> - return err;
> + return 0;
> }
> subsys_initcall(default_bdi_init);
>
> @@ -781,7 +774,7 @@ static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
>
> #endif /* CONFIG_CGROUP_WRITEBACK */
>
> -static int bdi_init(struct backing_dev_info *bdi)
> +int bdi_init(struct backing_dev_info *bdi)
> {
> int ret;
>
On Wed 15-06-22 23:08:22, Christoph Hellwig wrote:
> On Wed, Jun 15, 2022 at 11:48:15PM +0200, Jan Kara wrote:
> > +extern int bdi_init(struct backing_dev_info *bdi);
>
> No need for the extern.
Yes, fixed up.
> Otherwise looks good:
>
> Reviewed-by: Christoph Hellwig <[email protected]>
Thanks for review!
> And this remind me that I really want to kill noop_backing_dev_info
> and just use a NULL bdi for this case eventually..
Yes, I'm just not sure whether the checks for bdi / wb being NULL in lots
of places will not be too annoying... But maybe you'll be able to come up
with some wrappers that will make things bearable.
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR