syzbot has reported an interesting issue:
INFO: task syz-executor888:3126 blocked for more than 143 seconds.
Not tainted 6.1.0-rc6-syzkaller-32662-g6d464646530f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor888 state:D stack:0 pid:3126 ppid:3124 flags:0x00000000
Call trace:
__switch_to+0x180/0x298 arch/arm64/kernel/process.c:553
context_switch kernel/sched/core.c:5209 [inline]
__schedule+0x408/0x594 kernel/sched/core.c:6521
schedule+0x64/0xa4 kernel/sched/core.c:6597
schedule_timeout+0x108/0x1b4 kernel/time/timer.c:1935
gfs2_gl_hash_clear+0xd4/0x1b0 fs/gfs2/glock.c:2263
gfs2_put_super+0x318/0x390 fs/gfs2/super.c:620
generic_shutdown_super+0x94/0x198 fs/super.c:492
kill_block_super+0x30/0x78 fs/super.c:1428
gfs2_kill_sb+0x68/0x78
deactivate_locked_super+0x70/0xe8 fs/super.c:332
deactivate_super+0xd0/0xd4 fs/super.c:363
cleanup_mnt+0x184/0x1c0 fs/namespace.c:1186
__cleanup_mnt+0x20/0x30 fs/namespace.c:1193
task_work_run+0x100/0x148 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/11:
#0: ffff80000d4a4768 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
1 lock held by rcu_tasks_trace/12:
#0: ffff80000d4a4db8 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
1 lock held by khungtaskd/27:
#0: ffff80000d4a4640 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:303
2 locks held by getty/2759:
#0: ffff0000c7d7e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x28/0x58 drivers/tty/tty_ldisc.c:244
#1: ffff80000f6be2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x19c/0x89c drivers/tty/n_tty.c:2177
1 lock held by syz-executor888/3126:
#0: ffff0000cae680e0 (&type->s_umount_key#41){+.+.}-{3:3}, at: deactivate_super+0xc8/0xd4 fs/super.c:362
=============================================
One task blocked after executing gfs2_gl_hash_clear(), it looks
like go to sleep for waiting the condition (&sdp->sd_glock_disposal == 0),
this field sd_glock_disposal is used to count the getting times
that calling gfs2_glock_get() success, In most cases, when we operate
the mount interface, we will finally call this function:
do_mount()
path_mount()
vfs_get_tree()
gfs2_get_tree()
get_tree_bdev()
gfs2_fill_super()
________ init_inodes()_____________
V V
gfs2_lookup_simple() gfs2_rindex_update()
gfs2_lookupi() gfs2_ri_update()
gfs2_dir_search() -> read_rindex_entry() //*gfs2_rgrpd->rd_gl
-> gfs2_inode_lookup() //*gfs2_inode->i_gl |__ gfs2_glock_get()
|__gfs2_glock_get()
Correspondingly, release this glock's reference and decrease
sdp->sd_glock_disposal through this path when umount:
cleanup_mnt()
deactivate_super()
deactivate_locked_super()
gfs2_kill_sb()
kill_block_super()
generic_shutdown_super()
_gfs2_rgrpd->rd_gl__gfs2_put_super()__gfs2_inode->i_gl__
V V
gfs2_clear_rgrpd() gfs2_put_super()
gfs2_glock_put() iput()
gfs2_glock_free() evict()
gfs2_evict_inode()
gfs2_glock_put_eventually()
gfs2_glock_put()
gfs2_glock_free()
But if calling reconfigure_super() from sysfs between mount and umount,
this path will also take the glock lock and increase sdp->sd_glock_disposal
as it also call gfs2_glock_get():
reconfigure_super()
gfs2_reconfigure()
gfs2_make_fs_rw() //remount filesystem read-write
gfs2_quota_init()
-> qd_alloc() //*gfs2_quota_data->qd_gl
|___ gfs2_glock_get()
This relies on gfs2_quota_cleanup() that is eventually called by
gfs2_make_fs_ro() to clean up but unfortunately the file system
has not been remounted at this time, the condition (!sb_rdonly(sb))
is false and gfs2_make_fs_ro() can not be called, ultimately makes
sdp->sd_glock_disposal never be 0.
This add calling gfs2_quota_cleanup() when this filesystem remains
readOnly, in this case we don't need sync quota or other operation
otherwise the filesystem was really remounted.
But this modification will trigger this warning:
WARNING: CPU: 7 PID: 2595 at include/linux/backing-dev.h:246 __folio_mark_dirty+0x559/0x7b0
We can filter this warning with adding a parameter as it doesn't
really make sense here.
Fixes: 9e6e0a128bca ("GFS2: Merge mount.c and ops_super.c into super.c")
Reported-by: [email protected]
Signed-off-by: Wang ShaoBo <[email protected]>
---
fs/gfs2/super.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index b018957a1bb2..9a3c6da8db55 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -586,7 +586,10 @@ static void gfs2_put_super(struct super_block *sb)
if (!sb_rdonly(sb)) {
gfs2_make_fs_ro(sdp);
+ } else {
+ gfs2_quota_cleanup(sdp);
}
+
WARN_ON(gfs2_withdrawing(sdp));
/* At this point, we're through modifying the disk */
--
2.25.1
?? 2022/12/1 19:50, Wang ShaoBo д??:
> syzbot has reported an interesting issue:
>
> INFO: task syz-executor888:3126 blocked for more than 143 seconds.
> Not tainted 6.1.0-rc6-syzkaller-32662-g6d464646530f #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor888 state:D stack:0 pid:3126 ppid:3124 flags:0x00000000
> Call trace:
> __switch_to+0x180/0x298 arch/arm64/kernel/process.c:553
> context_switch kernel/sched/core.c:5209 [inline]
> __schedule+0x408/0x594 kernel/sched/core.c:6521
> schedule+0x64/0xa4 kernel/sched/core.c:6597
> schedule_timeout+0x108/0x1b4 kernel/time/timer.c:1935
> gfs2_gl_hash_clear+0xd4/0x1b0 fs/gfs2/glock.c:2263
> gfs2_put_super+0x318/0x390 fs/gfs2/super.c:620
> generic_shutdown_super+0x94/0x198 fs/super.c:492
> kill_block_super+0x30/0x78 fs/super.c:1428
> gfs2_kill_sb+0x68/0x78
> deactivate_locked_super+0x70/0xe8 fs/super.c:332
> deactivate_super+0xd0/0xd4 fs/super.c:363
> cleanup_mnt+0x184/0x1c0 fs/namespace.c:1186
> __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
> task_work_run+0x100/0x148 kernel/task_work.c:179
> resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
> do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
> prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
> exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
> el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
> el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
> el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
>
> Showing all locks held in the system:
> 1 lock held by rcu_tasks_kthre/11:
> #0: ffff80000d4a4768 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
> 1 lock held by rcu_tasks_trace/12:
> #0: ffff80000d4a4db8 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
> 1 lock held by khungtaskd/27:
> #0: ffff80000d4a4640 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:303
> 2 locks held by getty/2759:
> #0: ffff0000c7d7e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x28/0x58 drivers/tty/tty_ldisc.c:244
> #1: ffff80000f6be2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x19c/0x89c drivers/tty/n_tty.c:2177
> 1 lock held by syz-executor888/3126:
> #0: ffff0000cae680e0 (&type->s_umount_key#41){+.+.}-{3:3}, at: deactivate_super+0xc8/0xd4 fs/super.c:362
>
> =============================================
>
> One task blocked after executing gfs2_gl_hash_clear(), it looks
> like go to sleep for waiting the condition (&sdp->sd_glock_disposal == 0),
> this field sd_glock_disposal is used to count the getting times
> that calling gfs2_glock_get() success, In most cases, when we operate
> the mount interface, we will finally call this function:
>
> do_mount()
> path_mount()
> vfs_get_tree()
> gfs2_get_tree()
> get_tree_bdev()
> gfs2_fill_super()
> ________ init_inodes()_____________
> V V
> gfs2_lookup_simple() gfs2_rindex_update()
> gfs2_lookupi() gfs2_ri_update()
> gfs2_dir_search() -> read_rindex_entry() //*gfs2_rgrpd->rd_gl
> -> gfs2_inode_lookup() //*gfs2_inode->i_gl |__ gfs2_glock_get()
> |__gfs2_glock_get()
>
> Correspondingly, release this glock's reference and decrease
> sdp->sd_glock_disposal through this path when umount:
>
> cleanup_mnt()
> deactivate_super()
> deactivate_locked_super()
> gfs2_kill_sb()
> kill_block_super()
> generic_shutdown_super()
> _gfs2_rgrpd->rd_gl__gfs2_put_super()__gfs2_inode->i_gl__
> V V
> gfs2_clear_rgrpd() gfs2_put_super()
> gfs2_glock_put() iput()
> gfs2_glock_free() evict()
> gfs2_evict_inode()
> gfs2_glock_put_eventually()
> gfs2_glock_put()
> gfs2_glock_free()
>
> But if calling reconfigure_super() from sysfs between mount and umount,
> this path will also take the glock lock and increase sdp->sd_glock_disposal
> as it also call gfs2_glock_get():
>
> reconfigure_super()
> gfs2_reconfigure()
> gfs2_make_fs_rw() //remount filesystem read-write
> gfs2_quota_init()
> -> qd_alloc() //*gfs2_quota_data->qd_gl
> |___ gfs2_glock_get()
>
> This relies on gfs2_quota_cleanup() that is eventually called by
> gfs2_make_fs_ro() to clean up but unfortunately the file system
> has not been remounted at this time, the condition (!sb_rdonly(sb))
> is false and gfs2_make_fs_ro() can not be called, ultimately makes
> sdp->sd_glock_disposal never be 0.
>
> This add calling gfs2_quota_cleanup() when this filesystem remains
> readOnly, in this case we don't need sync quota or other operation
> otherwise the filesystem was really remounted.
>
> But this modification will trigger this warning:
>
> WARNING: CPU: 7 PID: 2595 at include/linux/backing-dev.h:246 __folio_mark_dirty+0x559/0x7b0
I paste wrong, the warning is:
gfs2: fsid=mounts.0: warning: assertion "!qd->qd_change" failed at
function = gfs2_quota_cleanup, file = fs/gfs2/quota.c, line = 1474
qd->qd_change has been changed in gfs2_quota_init(), but it looks
we don't need to do anything before remounting the file system as
read-write.
>
> We can filter this warning with adding a parameter as it doesn't
> really make sense here.
>
> Fixes: 9e6e0a128bca ("GFS2: Merge mount.c and ops_super.c into super.c")
> Reported-by: [email protected]
> Signed-off-by: Wang ShaoBo <[email protected]>
> ---
> fs/gfs2/super.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
> index b018957a1bb2..9a3c6da8db55 100644
> --- a/fs/gfs2/super.c
> +++ b/fs/gfs2/super.c
> @@ -586,7 +586,10 @@ static void gfs2_put_super(struct super_block *sb)
>
> if (!sb_rdonly(sb)) {
> gfs2_make_fs_ro(sdp);
> + } else {
> + gfs2_quota_cleanup(sdp);
> }
> +
> WARN_ON(gfs2_withdrawing(sdp));
>
> /* At this point, we're through modifying the disk */
>
Hello,
thank you for this bug report.
On Sat, Dec 3, 2022 at 8:28 AM Wangshaobo (bobo)
<[email protected]> wrote:
> 在 2022/12/1 19:50, Wang ShaoBo 写道:
> > syzbot has reported an interesting issue:
> >
> > INFO: task syz-executor888:3126 blocked for more than 143 seconds.
> > Not tainted 6.1.0-rc6-syzkaller-32662-g6d464646530f #0
> > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > task:syz-executor888 state:D stack:0 pid:3126 ppid:3124 flags:0x00000000
> > Call trace:
> > __switch_to+0x180/0x298 arch/arm64/kernel/process.c:553
> > context_switch kernel/sched/core.c:5209 [inline]
> > __schedule+0x408/0x594 kernel/sched/core.c:6521
> > schedule+0x64/0xa4 kernel/sched/core.c:6597
> > schedule_timeout+0x108/0x1b4 kernel/time/timer.c:1935
> > gfs2_gl_hash_clear+0xd4/0x1b0 fs/gfs2/glock.c:2263
> > gfs2_put_super+0x318/0x390 fs/gfs2/super.c:620
> > generic_shutdown_super+0x94/0x198 fs/super.c:492
> > kill_block_super+0x30/0x78 fs/super.c:1428
> > gfs2_kill_sb+0x68/0x78
> > deactivate_locked_super+0x70/0xe8 fs/super.c:332
> > deactivate_super+0xd0/0xd4 fs/super.c:363
> > cleanup_mnt+0x184/0x1c0 fs/namespace.c:1186
> > __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
> > task_work_run+0x100/0x148 kernel/task_work.c:179
> > resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
> > do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
> > prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
> > exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
> > el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
> > el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
> > el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
> >
> > Showing all locks held in the system:
> > 1 lock held by rcu_tasks_kthre/11:
> > #0: ffff80000d4a4768 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
> > 1 lock held by rcu_tasks_trace/12:
> > #0: ffff80000d4a4db8 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
> > 1 lock held by khungtaskd/27:
> > #0: ffff80000d4a4640 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:303
> > 2 locks held by getty/2759:
> > #0: ffff0000c7d7e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x28/0x58 drivers/tty/tty_ldisc.c:244
> > #1: ffff80000f6be2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x19c/0x89c drivers/tty/n_tty.c:2177
> > 1 lock held by syz-executor888/3126:
> > #0: ffff0000cae680e0 (&type->s_umount_key#41){+.+.}-{3:3}, at: deactivate_super+0xc8/0xd4 fs/super.c:362
> >
> > =============================================
> >
> > One task blocked after executing gfs2_gl_hash_clear(), it looks
> > like go to sleep for waiting the condition (&sdp->sd_glock_disposal == 0),
> > this field sd_glock_disposal is used to count the getting times
> > that calling gfs2_glock_get() success, In most cases, when we operate
> > the mount interface, we will finally call this function:
> >
> > do_mount()
> > path_mount()
> > vfs_get_tree()
> > gfs2_get_tree()
> > get_tree_bdev()
> > gfs2_fill_super()
> > ________ init_inodes()_____________
> > V V
> > gfs2_lookup_simple() gfs2_rindex_update()
> > gfs2_lookupi() gfs2_ri_update()
> > gfs2_dir_search() -> read_rindex_entry() //*gfs2_rgrpd->rd_gl
> > -> gfs2_inode_lookup() //*gfs2_inode->i_gl |__ gfs2_glock_get()
> > |__gfs2_glock_get()
> >
> > Correspondingly, release this glock's reference and decrease
> > sdp->sd_glock_disposal through this path when umount:
> >
> > cleanup_mnt()
> > deactivate_super()
> > deactivate_locked_super()
> > gfs2_kill_sb()
> > kill_block_super()
> > generic_shutdown_super()
> > _gfs2_rgrpd->rd_gl__gfs2_put_super()__gfs2_inode->i_gl__
> > V V
> > gfs2_clear_rgrpd() gfs2_put_super()
> > gfs2_glock_put() iput()
> > gfs2_glock_free() evict()
> > gfs2_evict_inode()
> > gfs2_glock_put_eventually()
> > gfs2_glock_put()
> > gfs2_glock_free()
> >
> > But if calling reconfigure_super() from sysfs between mount and umount,
How are you doing that?
> > this path will also take the glock lock and increase sdp->sd_glock_disposal
> > as it also call gfs2_glock_get():
> >
> > reconfigure_super()
> > gfs2_reconfigure()
> > gfs2_make_fs_rw() //remount filesystem read-write
> > gfs2_quota_init()
> > -> qd_alloc() //*gfs2_quota_data->qd_gl
> > |___ gfs2_glock_get()
> >
> > This relies on gfs2_quota_cleanup() that is eventually called by
> > gfs2_make_fs_ro() to clean up but unfortunately the file system
> > has not been remounted at this time, the condition (!sb_rdonly(sb))
> > is false and gfs2_make_fs_ro() can not be called, ultimately makes
> > sdp->sd_glock_disposal never be 0.
> >
> > This add calling gfs2_quota_cleanup() when this filesystem remains
> > readOnly, in this case we don't need sync quota or other operation
> > otherwise the filesystem was really remounted.
> >
> > But this modification will trigger this warning:
> >
> > WARNING: CPU: 7 PID: 2595 at include/linux/backing-dev.h:246 __folio_mark_dirty+0x559/0x7b0
> I paste wrong, the warning is:
> gfs2: fsid=mounts.0: warning: assertion "!qd->qd_change" failed at
> function = gfs2_quota_cleanup, file = fs/gfs2/quota.c, line = 1474
Thanks, this is making more sense now.
> qd->qd_change has been changed in gfs2_quota_init(), but it looks
> we don't need to do anything before remounting the file system as
> read-write.
> >
> > We can filter this warning with adding a parameter as it doesn't
> > really make sense here.
> >
> > Fixes: 9e6e0a128bca ("GFS2: Merge mount.c and ops_super.c into super.c")
> > Reported-by: [email protected]
> > Signed-off-by: Wang ShaoBo <[email protected]>
> > ---
> > fs/gfs2/super.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
> > index b018957a1bb2..9a3c6da8db55 100644
> > --- a/fs/gfs2/super.c
> > +++ b/fs/gfs2/super.c
> > @@ -586,7 +586,10 @@ static void gfs2_put_super(struct super_block *sb)
> >
> > if (!sb_rdonly(sb)) {
> > gfs2_make_fs_ro(sdp);
> > + } else {
> > + gfs2_quota_cleanup(sdp);
> > }
> > +
> > WARN_ON(gfs2_withdrawing(sdp));
> >
> > /* At this point, we're through modifying the disk */
> >
>
Andreas
在 2022/12/3 21:15, Andreas Gruenbacher 写道:
> Hello,
>
> thank you for this bug report.
>
> On Sat, Dec 3, 2022 at 8:28 AM Wangshaobo (bobo)
> <[email protected]> wrote:
>> 在 2022/12/1 19:50, Wang ShaoBo 写道:
>>> syzbot has reported an interesting issue:
>>>
>>> INFO: task syz-executor888:3126 blocked for more than 143 seconds.
>>> Not tainted 6.1.0-rc6-syzkaller-32662-g6d464646530f #0
>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>> task:syz-executor888 state:D stack:0 pid:3126 ppid:3124 flags:0x00000000
>>> Call trace:
>>> __switch_to+0x180/0x298 arch/arm64/kernel/process.c:553
>>> context_switch kernel/sched/core.c:5209 [inline]
>>> __schedule+0x408/0x594 kernel/sched/core.c:6521
>>> schedule+0x64/0xa4 kernel/sched/core.c:6597
>>> schedule_timeout+0x108/0x1b4 kernel/time/timer.c:1935
>>> gfs2_gl_hash_clear+0xd4/0x1b0 fs/gfs2/glock.c:2263
>>> gfs2_put_super+0x318/0x390 fs/gfs2/super.c:620
>>> generic_shutdown_super+0x94/0x198 fs/super.c:492
>>> kill_block_super+0x30/0x78 fs/super.c:1428
>>> gfs2_kill_sb+0x68/0x78
>>> deactivate_locked_super+0x70/0xe8 fs/super.c:332
>>> deactivate_super+0xd0/0xd4 fs/super.c:363
>>> cleanup_mnt+0x184/0x1c0 fs/namespace.c:1186
>>> __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
>>> task_work_run+0x100/0x148 kernel/task_work.c:179
>>> resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
>>> do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
>>> prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
>>> exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
>>> el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
>>> el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
>>> el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
>>>
>>> Showing all locks held in the system:
>>> 1 lock held by rcu_tasks_kthre/11:
>>> #0: ffff80000d4a4768 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
>>> 1 lock held by rcu_tasks_trace/12:
>>> #0: ffff80000d4a4db8 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x3c/0x450 kernel/rcu/tasks.h:507
>>> 1 lock held by khungtaskd/27:
>>> #0: ffff80000d4a4640 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:303
>>> 2 locks held by getty/2759:
>>> #0: ffff0000c7d7e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x28/0x58 drivers/tty/tty_ldisc.c:244
>>> #1: ffff80000f6be2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x19c/0x89c drivers/tty/n_tty.c:2177
>>> 1 lock held by syz-executor888/3126:
>>> #0: ffff0000cae680e0 (&type->s_umount_key#41){+.+.}-{3:3}, at: deactivate_super+0xc8/0xd4 fs/super.c:362
>>>
>>> =============================================
>>>
>>> One task blocked after executing gfs2_gl_hash_clear(), it looks
>>> like go to sleep for waiting the condition (&sdp->sd_glock_disposal == 0),
>>> this field sd_glock_disposal is used to count the getting times
>>> that calling gfs2_glock_get() success, In most cases, when we operate
>>> the mount interface, we will finally call this function:
>>>
>>> do_mount()
>>> path_mount()
>>> vfs_get_tree()
>>> gfs2_get_tree()
>>> get_tree_bdev()
>>> gfs2_fill_super()
>>> ________ init_inodes()_____________
>>> V V
>>> gfs2_lookup_simple() gfs2_rindex_update()
>>> gfs2_lookupi() gfs2_ri_update()
>>> gfs2_dir_search() -> read_rindex_entry() //*gfs2_rgrpd->rd_gl
>>> -> gfs2_inode_lookup() //*gfs2_inode->i_gl |__ gfs2_glock_get()
>>> |__gfs2_glock_get()
>>>
>>> Correspondingly, release this glock's reference and decrease
>>> sdp->sd_glock_disposal through this path when umount:
>>>
>>> cleanup_mnt()
>>> deactivate_super()
>>> deactivate_locked_super()
>>> gfs2_kill_sb()
>>> kill_block_super()
>>> generic_shutdown_super()
>>> _gfs2_rgrpd->rd_gl__gfs2_put_super()__gfs2_inode->i_gl__
>>> V V
>>> gfs2_clear_rgrpd() gfs2_put_super()
>>> gfs2_glock_put() iput()
>>> gfs2_glock_free() evict()
>>> gfs2_evict_inode()
>>> gfs2_glock_put_eventually()
>>> gfs2_glock_put()
>>> gfs2_glock_free()
>>>
>>> But if calling reconfigure_super() from sysfs between mount and umount,
>
> How are you doing that?
>
I tested multiple times and trace corresponding path, and analyzed the
trigger mechanism, it looks a bit complicated - -.
>>> this path will also take the glock lock and increase sdp->sd_glock_disposal
>>> as it also call gfs2_glock_get():
>>>
>>> reconfigure_super()
>>> gfs2_reconfigure()
>>> gfs2_make_fs_rw() //remount filesystem read-write
>>> gfs2_quota_init()
>>> -> qd_alloc() //*gfs2_quota_data->qd_gl
>>> |___ gfs2_glock_get()
>>>
>>> This relies on gfs2_quota_cleanup() that is eventually called by
>>> gfs2_make_fs_ro() to clean up but unfortunately the file system
>>> has not been remounted at this time, the condition (!sb_rdonly(sb))
>>> is false and gfs2_make_fs_ro() can not be called, ultimately makes
>>> sdp->sd_glock_disposal never be 0.
>>>
>>> This add calling gfs2_quota_cleanup() when this filesystem remains
>>> readOnly, in this case we don't need sync quota or other operation
>>> otherwise the filesystem was really remounted.
>>>
>>> But this modification will trigger this warning:
>>>
>>> WARNING: CPU: 7 PID: 2595 at include/linux/backing-dev.h:246 __folio_mark_dirty+0x559/0x7b0
>> I paste wrong, the warning is:
>> gfs2: fsid=mounts.0: warning: assertion "!qd->qd_change" failed at
>> function = gfs2_quota_cleanup, file = fs/gfs2/quota.c, line = 1474
>
> Thanks, this is making more sense now.
>
why it makes more sense now ?
>> qd->qd_change has been changed in gfs2_quota_init(), but it looks
>> we don't need to do anything before remounting the file system as
>> read-write.
>>>
>>> We can filter this warning with adding a parameter as it doesn't
>>> really make sense here.
>>>
>>> Fixes: 9e6e0a128bca ("GFS2: Merge mount.c and ops_super.c into super.c")
>>> Reported-by: [email protected]
>>> Signed-off-by: Wang ShaoBo <[email protected]>
>>> ---
>>> fs/gfs2/super.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
>>> index b018957a1bb2..9a3c6da8db55 100644
>>> --- a/fs/gfs2/super.c
>>> +++ b/fs/gfs2/super.c
>>> @@ -586,7 +586,10 @@ static void gfs2_put_super(struct super_block *sb)
>>>
>>> if (!sb_rdonly(sb)) {
>>> gfs2_make_fs_ro(sdp);
>>> + } else {
>>> + gfs2_quota_cleanup(sdp);
>>> }
>>> +
>>> WARN_ON(gfs2_withdrawing(sdp));
>>>
>>> /* At this point, we're through modifying the disk */
>>>
>>
>
> Andreas
>
> .
>
-- Wang ShaoBo