From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout3.samsung.com (mailout3.samsung.com [203.254.224.33]) (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 C11B719D09C for ; Fri, 8 Aug 2025 05:09:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.254.224.33 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754629745; cv=none; b=eGSJ2KzENmv53rKKv167FJmYOhkct81b2Khct1fc+Qyp66MXNUmEnhsozttsCyeedRm60XsVsjfr/KeYQW4DIqqeGlF66I+0ySE6pbRIkFCW7JPBwwcDcW/TdXaBYps3NwnopTOMXtqtYALLh0yPSA1rX8UsCcYa4uFmUiMT9x4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754629745; c=relaxed/simple; bh=YsLMrkf+1ivzC8WoJA/+R7/IB2icXE+D3ZYrrS1/KPI=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type: References; b=VLkdNSAkphCDR8TGd94sIsV/jXHY9Wo3M4rR5QzyURxDJAykbln7/s4XnAVKhNqEOeTMSVSd6QLNTy18K+I9Upe8WGC9Ku+cVURzGXAT6HQZdhLr4QLmJ6V5N/xKAQAlTFTsjjS10rRhV16+Y0Dpkb/vvofEKVLXf1XK5/HDiQM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=dDwFfJdz; arc=none smtp.client-ip=203.254.224.33 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="dDwFfJdz" Received: from epcas2p1.samsung.com (unknown [182.195.41.53]) by mailout3.samsung.com (KnoxPortal) with ESMTP id 20250808050854epoutp034cb748db63862a1db2df77cbb09b069c~ZsnJ4NaUb1718517185epoutp03D for ; Fri, 8 Aug 2025 05:08:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout3.samsung.com 20250808050854epoutp034cb748db63862a1db2df77cbb09b069c~ZsnJ4NaUb1718517185epoutp03D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1754629734; bh=u3huiNdu0rRAya2M/kre/HuzuylCu0m0RuGmkyeYlU4=; h=From:To:Subject:Date:References:From; b=dDwFfJdznR7YeHoHrN0tY0n4xOehu7TNaS/C1Krg+K/mam2WC2hxeImS6gc5wxpih mzW522mqaPZANzADwhgE5rXQjouEQMIzu2Br1fXwng6mHB8fXmWs+nyfQWEU1mKU5y k04L8FnZUu5dMdiAHKoJXbJJwPTz/V7jnkz/1eCw= Received: from epsnrtp02.localdomain (unknown [182.195.42.154]) by epcas2p2.samsung.com (KnoxPortal) with ESMTPS id 20250808050854epcas2p2df1b856b6a98c0feaced3206054adf63~ZsnJXsUMd3201832018epcas2p2W; Fri, 8 Aug 2025 05:08:54 +0000 (GMT) Received: from epcas2p1.samsung.com (unknown [182.195.36.89]) by epsnrtp02.localdomain (Postfix) with ESMTP id 4bysWT2W8fz2SSKY; Fri, 8 Aug 2025 05:08:53 +0000 (GMT) Received: from epsmtip1.samsung.com (unknown [182.195.34.30]) by epcas2p4.samsung.com (KnoxPortal) with ESMTPA id 20250808050852epcas2p41faca5b3fd8a7bc18cc173ce44650bff~ZsnIKI84i0265402654epcas2p4F; Fri, 8 Aug 2025 05:08:52 +0000 (GMT) Received: from KORCO118546 (unknown [12.36.150.57]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250808050852epsmtip12823c61b1c9681d1f46a0d01cd41bd14~ZsnIFlj6d1991519915epsmtip1D; Fri, 8 Aug 2025 05:08:52 +0000 (GMT) From: "hoyoung seo" To: , , , , , , , , , , , , , Subject: Questions about dquota write by writeback in the context of storage shortage Date: Fri, 8 Aug 2025 14:08:52 +0900 Message-ID: <000001dc0822$886fc990$994f5cb0$@samsung.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AdwIIoPDH3+1YAVzRxe4KvlMHLhSQA== Content-Language: ko X-CMS-MailID: 20250808050852epcas2p41faca5b3fd8a7bc18cc173ce44650bff X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P X-CPGSPASS: Y cpgsPolicy: CPGSC10-234,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250808050852epcas2p41faca5b3fd8a7bc18cc173ce44650bff References: Hi, When the storage usage was full(99%), the following panic_on_warm occurred. In this case, wb_writeback function used writeback workqeue included WQ_MEM= _RECLAIM flag. And wb_writeback function called f2fs_write_single_data_page for updating d= quot(Write checkpoint to reclaim prefree segments) In this case, dquot_writback_dquots function use events_unbound workqueue. It is not include WQ_MEM_RECLAIM flag. So occurred this problem. First of all, I don't think this situation should be created, but I don't k= now why it's like this So I guess quota_release_workfn function should use workqueue with WQ_MEM_R= ECLAIM flag, but is this the right solution? workqueue: WQ_MEM_RECLAIM writeback:wb_workfn is flushing =21WQ_MEM_RECLAIM= events_unbound:quota_release_workfn Call trace: check_flush_dependency+0x160/0x16c __flush_work+0x168/0x738 flush_delayed_work+0x58/0x70 dquot_writeback_dquots+0x90/0x4bc f2fs_do_quota_sync+0x120/0x284 f2fs_write_checkpoint+0x58c/0xe18 f2fs_gc+0x3e8/0xd78 f2fs_balance_fs+0x204/0x284 f2fs_write_single_data_page+0x700/0xaf0 f2fs_write_data_pages+0xe94/0x15bc do_writepages+0x170/0x3f8 __writeback_single_inode+0xa0/0x8c4 writeback_sb_inodes+0x2ac/0x708 __writeback_inodes_wb+0xc0/0x118 wb_writeback+0x1f4/0x664 wb_workfn+0x62c/0x900 Thanks.