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charset="utf-8" One of the paths quota writeback is called from is: freeze_super() sync_filesystem() ext4_sync_fs() dquot_writeback_dquots() Since we currently don't always flush the quota_release_work queue in this path, we can end up with the following race: 1. dquot are added to releasing_dquots list during regular operations. 2. FS Freeze starts, however, this does not flush the quota_release_work q= ueue. 3. Freeze completes. 4. Kernel eventually tries to flush the workqueue while FS is frozen which hits a WARN_ON since transaction gets started during frozen state: ext4_journal_check_start+0x28/0x110 [ext4] (unreliable) __ext4_journal_start_sb+0x64/0x1c0 [ext4] ext4_release_dquot+0x90/0x1d0 [ext4] quota_release_workfn+0x43c/0x4d0 Which is the following line: WARN_ON(sb->s_writers.frozen =3D=3D SB_FREEZE_COMPLETE); Which ultimately results in generic/390 failing due to dmesg noise. This was detected on powerpc machine 15 cores. To avoid this, make sure to flush the workqueue during dquot_writeback_dquots() so we dont have any pending workitems after freeze. Reported-by: Disha Goel Signed-off-by: Ojaswin Mujoo --- fs/quota/dquot.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 3dd8d6f27725..f9578918cfb2 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -688,6 +688,8 @@ int dquot_writeback_dquots(struct super_block *sb, int = type) =20 WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount)); =20 + flush_delayed_work("a_release_work); + for (cnt =3D 0; cnt < MAXQUOTAS; cnt++) { if (type !=3D -1 && cnt !=3D type) continue; --=20 2.43.5 From nobody Fri Nov 22 16:52:01 2024 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6F001D88DB; Thu, 21 Nov 2024 12:39:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; 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charset="utf-8" Protect ext4_release_dquot against freezing so that we don't try to start a transaction when FS is frozen, leading to warnings. Further, avoid taking the freeze protection if a transaction is already running so that we don't need end up in a deadlock as described in 46e294efc355 ext4: fix deadlock with fs freezing and EA inodes Suggested-by: Jan Kara Signed-off-by: Ojaswin Mujoo --- fs/ext4/super.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 16a4ce704460..f7437a592359 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -6887,12 +6887,25 @@ static int ext4_release_dquot(struct dquot *dquot) { int ret, err; handle_t *handle; + bool freeze_protected =3D false; + + /* + * Trying to sb_start_intwrite() in a running transaction + * can result in a deadlock. Further, running transactions + * are already protected from freezing. + */ + if (!ext4_journal_current_handle()) { + sb_start_intwrite(dquot->dq_sb); + freeze_protected =3D true; + } =20 handle =3D ext4_journal_start(dquot_to_inode(dquot), EXT4_HT_QUOTA, EXT4_QUOTA_DEL_BLOCKS(dquot->dq_sb)); if (IS_ERR(handle)) { /* Release dquot anyway to avoid endless cycle in dqput() */ dquot_release(dquot); + if (freeze_protected) + sb_end_intwrite(dquot->dq_sb); return PTR_ERR(handle); } ret =3D dquot_release(dquot); @@ -6903,6 +6916,10 @@ static int ext4_release_dquot(struct dquot *dquot) err =3D ext4_journal_stop(handle); if (!ret) ret =3D err; + + if (freeze_protected) + sb_end_intwrite(dquot->dq_sb); + return ret; } =20 --=20 2.43.5