Messages in this thread | | | Date | Tue, 30 May 2023 12:15:21 +0200 | From | Jan Kara <> | Subject | Re: [PATCH 2/2] quota: fix warning in dqgrab() |
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On Sat 27-05-23 09:40:18, Ye Bin wrote: > There's issue as follows when do fault injection: > WARNING: CPU: 1 PID: 14870 at include/linux/quotaops.h:51 dquot_disable+0x13b7/0x18c0 > Modules linked in: > CPU: 1 PID: 14870 Comm: fsconfig Not tainted 6.3.0-next-20230505-00006-g5107a9c821af-dirty #541 > RIP: 0010:dquot_disable+0x13b7/0x18c0 > RSP: 0018:ffffc9000acc79e0 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88825e41b980 > RDX: 0000000000000000 RSI: ffff88825e41b980 RDI: 0000000000000002 > RBP: ffff888179f68000 R08: ffffffff82087ca7 R09: 0000000000000000 > R10: 0000000000000001 R11: ffffed102f3ed026 R12: ffff888179f68130 > R13: ffff888179f68110 R14: dffffc0000000000 R15: ffff888179f68118 > FS: 00007f450a073740(0000) GS:ffff88882fc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007ffe96f2efd8 CR3: 000000025c8ad000 CR4: 00000000000006e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > dquot_load_quota_sb+0xd53/0x1060 > dquot_resume+0x172/0x230 > ext4_reconfigure+0x1dc6/0x27b0 > reconfigure_super+0x515/0xa90 > __x64_sys_fsconfig+0xb19/0xd20 > do_syscall_64+0x39/0xb0 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Above issue may happens as follows: > ProcessA ProcessB ProcessC > sys_fsconfig > vfs_fsconfig_locked > reconfigure_super > ext4_remount > dquot_suspend -> suspend all type quota > > sys_fsconfig > vfs_fsconfig_locked > reconfigure_super > ext4_remount > dquot_resume > ret = dquot_load_quota_sb > add_dquot_ref > do_open -> open file O_RDWR > vfs_open > do_dentry_open > get_write_access > atomic_inc_unless_negative(&inode->i_writecount) > ext4_file_open > dquot_file_open > dquot_initialize > __dquot_initialize > dqget > atomic_inc(&dquot->dq_count); > > __dquot_initialize > __dquot_initialize > dqget > if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) > ext4_acquire_dquot > -> Return error DQ_ACTIVE_B flag isn't set > dquot_disable > invalidate_dquots > if (atomic_read(&dquot->dq_count)) > dqgrab > WARN_ON_ONCE(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) > -> Trigger warning > > In the above scenario, 'dquot->dq_flags' has no DQ_ACTIVE_B is normal when > dqgrab(). > So just remove 'WARN_ON_ONCE(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))' > in dqgrab(). > > Signed-off-by: Ye Bin <yebin10@huawei.com>
Thanks for the patch! Actually rather than deleting the assertion from dqgrab() (which can be and is used by filesystems) I'd replace the dqgrab() use in invalidate_dquots() with plain:
atomic_inc(&dquot->dq_count);
Honza
> --- > include/linux/quotaops.h | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h > index 11a4becff3a9..cb5e4c11e503 100644 > --- a/include/linux/quotaops.h > +++ b/include/linux/quotaops.h > @@ -48,7 +48,6 @@ static inline struct dquot *dqgrab(struct dquot *dquot) > { > /* Make sure someone else has active reference to dquot */ > WARN_ON_ONCE(!atomic_read(&dquot->dq_count)); > - WARN_ON_ONCE(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)); > atomic_inc(&dquot->dq_count); > return dquot; > } > -- > 2.31.1 > -- Jan Kara <jack@suse.com> SUSE Labs, CR
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