From nobody Thu Apr 2 18:47:37 2026 Received: from sender4-op-o15.zoho.com (sender4-op-o15.zoho.com [136.143.188.15]) (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 6FAE72BAF7; Wed, 25 Feb 2026 08:26:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.15 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772008005; cv=pass; b=B1CFSRbelULG3zh5ueBNCVSjTT6cixPfnScwE4vxDv52Z7mIzGZqVY2DOrOwgAhkI3ZuzccnIYgGkpvJUXUwS2zfqmgrDv3uCSwKCf4KmxaH3r7ODl01C29BTrCo2DI3zhmTrLXCGlIuaB43MnaWqSyPMyCMMCf9Jd7r35EyH5Y= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772008005; c=relaxed/simple; bh=3Zs+4Z6kGJCt8+r1ClqjQ8R3MVkw7Gky1DWt97cA9Yo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Khphl0ZSgzVKlW67CREniRAVcJ/doewCNbG9tqUDuQNt3wkCafbOKGcKUXt/qfkzpoDUQ1woj3EXY1VHqxsKZH/xSJapfu85yECTgUvGY1/wymEG31IsA+ZIEMNeOEQkvmWk/AY+7UnHbg5R984cSLEkr9lewahcBInKIIN8jBI= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty; spf=pass smtp.mailfrom=linux.beauty; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b=a0fAUhfF; arc=pass smtp.client-ip=136.143.188.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.beauty Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b="a0fAUhfF" ARC-Seal: i=1; a=rsa-sha256; t=1772007996; cv=none; d=zohomail.com; s=zohoarc; b=OLWnJT/O9KCYP9NzPc8FI+xA+cbzvkroSi1SDaeZNDD8L7canxIoPAhcM3BksmQmIXGs9j6OIZ1LNir+o6ZyWMjdvzfwPB72N/SvDNLU2rIPT71sGp0BqMemhQ3+dYexqvq0sxXfVZm5yVkk0FDQhngAZ07Op68w59QTn+/2uxs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1772007996; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=KUnDOdVYhZNrQ8tAKZ27H6u3rYsiJ++SEPKPom+E9dM=; b=K7X3xQAsm6+1uq15cakWRxorijtsuMzFTKIEOgdLP0vyCwgvg8dmO9gVnbPmxZVEZH7yMuJUjRC9GpYoKAR27fvclmcUu4sBk0w6+z+u5+aDL1UHQ09LQ5L8ChkqLTdg9RmvOlqgj0f/goERWidSVfi2YjxuGkXFhWwtmCLR58g= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=linux.beauty; spf=pass smtp.mailfrom=me@linux.beauty; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1772007996; s=zmail; d=linux.beauty; i=me@linux.beauty; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=KUnDOdVYhZNrQ8tAKZ27H6u3rYsiJ++SEPKPom+E9dM=; b=a0fAUhfFWxo0SSfHhv4Hsi9jhWqn1Qsi9NvcKhscotFKvELao0cqI5n2OIBoOEx6 1F4gF4zHCQP8/n3bG7TVDVH3ETqB+lkMUvzxan+Ah9ZgvB1y1xhZJYEY5+rvORgQEDE aqLb62wUJGPxbZfMkPUG9a0Npna18ThPYa/N/L9w= Received: by mx.zohomail.com with SMTPS id 1772007993367826.5514012116394; Wed, 25 Feb 2026 00:26:33 -0800 (PST) From: Li Chen To: "Theodore Ts'o" , Andreas Dilger , Jan Kara , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Li Chen Subject: [PATCH v3] ext4: publish jinode after initialization Date: Wed, 25 Feb 2026 16:26:16 +0800 Message-ID: <20260225082617.147957-1-me@linux.beauty> X-Mailer: git-send-email 2.52.0 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-ZohoMailClient: External Content-Type: text/plain; charset="utf-8" ext4_inode_attach_jinode() publishes ei->jinode to concurrent users. It used to set ei->jinode before jbd2_journal_init_jbd_inode(), allowing a reader to observe a non-NULL jinode with i_vfs_inode still unset. The fast commit flush path can then pass this jinode to jbd2_wait_inode_data(), which dereferences i_vfs_inode->i_mapping and may crash. Below is the crash I observe: ``` BUG: unable to handle page fault for address: 000000010beb47f4 PGD 110e51067 P4D 110e51067 PUD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 1 UID: 0 PID: 4850 Comm: fc_fsync_bench_ Not tainted 6.18.0-00764-g795= a690c06a5 #1 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17= .0-2-2 04/01/2014 RIP: 0010:xas_find_marked+0x3d/0x2e0 Code: e0 03 48 83 f8 02 0f 84 f0 01 00 00 48 8b 47 08 48 89 c3 48 39 c6 0f = 82 fd 01 00 00 48 85 c9 74 3d 48 83 f9 03 77 63 4c 8b 0f <49> 8b 71 08 48 c= 7 47 18 00 00 00 00 48 89 f1 83 e1 03 48 83 f9 02 RSP: 0018:ffffbbee806e7bf0 EFLAGS: 00010246 RAX: 000000000010beb4 RBX: 000000000010beb4 RCX: 0000000000000003 RDX: 0000000000000001 RSI: 0000002000300000 RDI: ffffbbee806e7c10 RBP: 0000000000000001 R08: 0000002000300000 R09: 000000010beb47ec R10: ffff9ea494590090 R11: 0000000000000000 R12: 0000002000300000 R13: ffffbbee806e7c90 R14: ffff9ea494513788 R15: ffffbbee806e7c88 FS: 00007fc2f9e3e6c0(0000) GS:ffff9ea6b1444000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000010beb47f4 CR3: 0000000119ac5000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: filemap_get_folios_tag+0x87/0x2a0 __filemap_fdatawait_range+0x5f/0xd0 ? srso_alias_return_thunk+0x5/0xfbef5 ? __schedule+0x3e7/0x10c0 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ? srso_alias_return_thunk+0x5/0xfbef5 ? cap_safe_nice+0x37/0x70 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ? srso_alias_return_thunk+0x5/0xfbef5 filemap_fdatawait_range_keep_errors+0x12/0x40 ext4_fc_commit+0x697/0x8b0 ? ext4_file_write_iter+0x64b/0x950 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ? srso_alias_return_thunk+0x5/0xfbef5 ? vfs_write+0x356/0x480 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ext4_sync_file+0xf7/0x370 do_fsync+0x3b/0x80 ? syscall_trace_enter+0x108/0x1d0 __x64_sys_fdatasync+0x16/0x20 do_syscall_64+0x62/0x2c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ... ``` Fix this by initializing the jbd2_inode first. Use smp_wmb() and WRITE_ONCE() to publish ei->jinode after initialization. Readers use READ_ONCE() to fetch the pointer. Fixes: a361293f5fede ("jbd2: Fix oops in jbd2_journal_file_inode()") Cc: stable@vger.kernel.org Signed-off-by: Li Chen Reviewed-by: Jan Kara --- Changes since v2 (as suggested by Jan Kara: - Drop READ_ONCE() changes in ext4_jbd2_inode_add_*() and ext4_clear_inode(= ). - Inline READ_ONCE(ei->jinode) in ext4_fc_flush_data(). fs/ext4/fast_commit.c | 4 ++-- fs/ext4/inode.c | 15 +++++++++++---- 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index f575751f1cae..6e949c21842d 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -975,13 +975,13 @@ static int ext4_fc_flush_data(journal_t *journal) int ret =3D 0; =20 list_for_each_entry(ei, &sbi->s_fc_q[FC_Q_MAIN], i_fc_list) { - ret =3D jbd2_submit_inode_data(journal, ei->jinode); + ret =3D jbd2_submit_inode_data(journal, READ_ONCE(ei->jinode)); if (ret) return ret; } =20 list_for_each_entry(ei, &sbi->s_fc_q[FC_Q_MAIN], i_fc_list) { - ret =3D jbd2_wait_inode_data(journal, ei->jinode); + ret =3D jbd2_wait_inode_data(journal, READ_ONCE(ei->jinode)); if (ret) return ret; } diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index da96db5f2345..d99296d7315f 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -128,6 +128,8 @@ void ext4_inode_csum_set(struct inode *inode, struct ex= t4_inode *raw, static inline int ext4_begin_ordered_truncate(struct inode *inode, loff_t new_size) { + struct jbd2_inode *jinode =3D READ_ONCE(EXT4_I(inode)->jinode); + trace_ext4_begin_ordered_truncate(inode, new_size); /* * If jinode is zero, then we never opened the file for @@ -135,10 +137,10 @@ static inline int ext4_begin_ordered_truncate(struct = inode *inode, * jbd2_journal_begin_ordered_truncate() since there's no * outstanding writes we need to flush. */ - if (!EXT4_I(inode)->jinode) + if (!jinode) return 0; return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode), - EXT4_I(inode)->jinode, + jinode, new_size); } =20 @@ -4478,8 +4480,13 @@ int ext4_inode_attach_jinode(struct inode *inode) spin_unlock(&inode->i_lock); return -ENOMEM; } - ei->jinode =3D jinode; - jbd2_journal_init_jbd_inode(ei->jinode, inode); + jbd2_journal_init_jbd_inode(jinode, inode); + /* + * Publish ->jinode only after it is fully initialized so that + * readers never observe a partially initialized jbd2_inode. + */ + smp_wmb(); + WRITE_ONCE(ei->jinode, jinode); jinode =3D NULL; } spin_unlock(&inode->i_lock); --=20 2.52.0