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 <suzuki.poulose@xxxxxxx>
Reported-and-tested-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Reported-and-tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Works for me too. Thanks for the proper fix Tested-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
--- 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;
