Messages in this thread |  | | From | Andreas Gruenbacher <> | Date | Sat, 3 Dec 2022 14:15:11 +0100 | Subject | Re: [RFC PATCH] gfs2: Fix missing cleanup quota in gfs2_put_super() |
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Hello,
thank you for this bug report.
On Sat, Dec 3, 2022 at 8:28 AM Wangshaobo (bobo) <bobo.shaobowang@huawei.com> 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: syzbot+ed7d0f71a89e28557a77@syzkaller.appspotmail.com > > Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com> > > --- > > 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
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