[{"id":3675076,"web_url":"http://patchwork.ozlabs.org/comment/3675076/","msgid":"<730ef9ef-cd7f-455c-a815-f354e34b7596@canonical.com>","list_archive_url":null,"date":"2026-04-09T05:13:29","subject":"ACK: [SRU][N/Q][PATCH 0/1] Remount ext4 to readonly with data=journal\n mode may dump call trace","submitter":{"id":85372,"url":"http://patchwork.ozlabs.org/api/people/85372/","name":"Masahiro Yamada","email":"masahiro.yamada@canonical.com"},"content":"On 4/7/26 18:26, Gerald Yang wrote:\n> BugLink: https://bugs.launchpad.net/bugs/2147400\n>\n> [Impact]\n>\n> When journal is filled with some data and remount the filesystem to read-only in data=journal mode\n> it may dump the following call trace:\n> [ 71.629350] CPU: 0 UID: 0 PID: 177 Comm: kworker/u96:5 Tainted: G E 6.19.0-rc7 #1 PREEMPT(voluntary)\n> [ 71.629352] Tainted: [E]=UNSIGNED_MODULE\n> [ 71.629353] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009)/LXD, BIOS unknown 2/2/2022\n> [ 71.629354] Workqueue: writeback wb_workfn (flush-7:4)\n> [ 71.629359] RIP: 0010:ext4_journal_check_start+0x8b/0xd0\n> [ 71.629360] Code: 31 ff 45 31 c0 45 31 c9 e9 42 ad c4 00 48 8b 5d f8 b8 fb ff ff ff c9 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 c3 cc cc cc cc <0f> 0b b8 e2 ff ff ff eb c2 0f 0b eb\n> a9 44 8b 42 08 68 c7 53 ce b8\n> [ 71.629361] RSP: 0018:ffffcf32c0fdf6a8 EFLAGS: 00010202\n> [ 71.629364] RAX: ffff8f08c8505000 RBX: ffff8f08c67ee800 RCX: 0000000000000000\n> [ 71.629366] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000\n> [ 71.629367] RBP: ffffcf32c0fdf6b0 R08: 0000000000000001 R09: 0000000000000000\n> [ 71.629368] R10: ffff8f08db18b3a8 R11: 0000000000000000 R12: 0000000000000000\n> [ 71.629368] R13: 0000000000000002 R14: 0000000000000a48 R15: ffff8f08c67ee800\n> [ 71.629369] FS: 0000000000000000(0000) GS:ffff8f0a7d273000(0000) knlGS:0000000000000000\n> [ 71.629370] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n> [ 71.629371] CR2: 00007b66825905cc CR3: 000000011053d004 CR4: 0000000000772ef0\n> [ 71.629374] PKRU: 55555554\n> [ 71.629374] Call Trace:\n> [ 71.629378] \n> [ 71.629382] __ext4_journal_start_sb+0x38/0x1c0\n> [ 71.629383] mpage_prepare_extent_to_map+0x4af/0x580\n> [ 71.629389] ? sbitmap_get+0x73/0x180\n> [ 71.629399] ext4_do_writepages+0x3cc/0x10a0\n> [ 71.629400] ? kvm_sched_clock_read+0x11/0x20\n> [ 71.629409] ext4_writepages+0xc8/0x1b0\n> [ 71.629410] ? ext4_writepages+0xc8/0x1b0\n> [ 71.629411] do_writepages+0xc4/0x180\n> [ 71.629416] __writeback_single_inode+0x45/0x350\n> [ 71.629419] ? _raw_spin_unlock+0xe/0x40\n> [ 71.629423] writeback_sb_inodes+0x260/0x5c0\n> [ 71.629425] ? __schedule+0x4d1/0x1870\n> [ 71.629429] __writeback_inodes_wb+0x54/0x100\n> [ 71.629431] ? queue_io+0x82/0x140\n> [ 71.629433] wb_writeback+0x1ab/0x330\n> [ 71.629448] wb_workfn+0x31d/0x410\n> [ 71.629450] process_one_work+0x191/0x3e0\n> [ 71.629455] worker_thread+0x2e3/0x420\n>\n> [Fix]\n>\n> This upstream commit fixes the issue:\n> https://github.com/torvalds/linux/commit/f4a2b42e78914ff15630e71289adc589c3a8eb45\n>\n> All the discussions are in this thread:\n> https://lore.kernel.org/all/20260128074515.2028982-1-gerald.yang@canonical.com/\n>\n> [Test Plan]\n>\n> This can be easily reproduced by the following script:\n> mkdir -p mnt\n> dd if=/dev/zero of=ext4disk bs=1G count=2 oflag=direct\n> mkfs.ext4 ext4disk\n> tune2fs -o journal_data ext4disk\n> mount ext4disk mnt\n> fio --name=fiotest --rw=randwrite --bs=4k --runtime=3 --ioengine=libaio --iodepth=128 --numjobs=4 --filename=mnt/fiotest --filesize=1G --group_reporting\n> mount -o remount,ro ext4disk mnt\n> sync\n>\n> [Where problems could occur]\n>\n> When the call trace happens, there is no data lost, all the dirty data has been flushed to file system before remounting.\n> The fix is to make sure folio state is correct and update the xarray, so the writeback thread won't be trigger if there is no dirty data.\n> So if there is something really goes wrong, there still won't be data lost, even remount it to read-write mode again.\n>\n> Jan Kara (1):\n> ext4: fix stale xarray tags after writeback\n>\n> fs/ext4/page-io.c | 10 ++++++++--\n> 1 file changed, 8 insertions(+), 2 deletions(-)\n>\nAcked-by: Masahiro Yamada ","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=oVblwwY9;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com\n (client-ip=185.125.189.65; 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charset=\"utf-8\"; Format=\"flowed\"","Errors-To":"kernel-team-bounces@lists.ubuntu.com","Sender":"\"kernel-team\" "}},{"id":3675624,"web_url":"http://patchwork.ozlabs.org/comment/3675624/","msgid":"<0d1a3393-ebca-4df5-ab88-44395f540a4f@canonical.com>","list_archive_url":null,"date":"2026-04-10T03:08:47","subject":"ACK: [SRU][N/Q][PATCH 0/1] Remount ext4 to readonly with data=journal\n mode may dump call trace","submitter":{"id":92836,"url":"http://patchwork.ozlabs.org/api/people/92836/","name":"Yufeng Gao","email":"yufeng.gao@canonical.com"},"content":"On 7/4/26 19:26, Gerald Yang wrote:\n> BugLink: https://bugs.launchpad.net/bugs/2147400\n>\n> [Impact]\n>\n> When journal is filled with some data and remount the filesystem to read-only in data=journal mode\n> it may dump the following call trace:\n> [ 71.629350] CPU: 0 UID: 0 PID: 177 Comm: kworker/u96:5 Tainted: G E 6.19.0-rc7 #1 PREEMPT(voluntary)\n> [ 71.629352] Tainted: [E]=UNSIGNED_MODULE\n> [ 71.629353] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009)/LXD, BIOS unknown 2/2/2022\n> [ 71.629354] Workqueue: writeback wb_workfn (flush-7:4)\n> [ 71.629359] RIP: 0010:ext4_journal_check_start+0x8b/0xd0\n> [ 71.629360] Code: 31 ff 45 31 c0 45 31 c9 e9 42 ad c4 00 48 8b 5d f8 b8 fb ff ff ff c9 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 c3 cc cc cc cc <0f> 0b b8 e2 ff ff ff eb c2 0f 0b eb\n> a9 44 8b 42 08 68 c7 53 ce b8\n> [ 71.629361] RSP: 0018:ffffcf32c0fdf6a8 EFLAGS: 00010202\n> [ 71.629364] RAX: ffff8f08c8505000 RBX: ffff8f08c67ee800 RCX: 0000000000000000\n> [ 71.629366] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000\n> [ 71.629367] RBP: ffffcf32c0fdf6b0 R08: 0000000000000001 R09: 0000000000000000\n> [ 71.629368] R10: ffff8f08db18b3a8 R11: 0000000000000000 R12: 0000000000000000\n> [ 71.629368] R13: 0000000000000002 R14: 0000000000000a48 R15: ffff8f08c67ee800\n> [ 71.629369] FS: 0000000000000000(0000) GS:ffff8f0a7d273000(0000) knlGS:0000000000000000\n> [ 71.629370] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n> [ 71.629371] CR2: 00007b66825905cc CR3: 000000011053d004 CR4: 0000000000772ef0\n> [ 71.629374] PKRU: 55555554\n> [ 71.629374] Call Trace:\n> [ 71.629378] \n> [ 71.629382] __ext4_journal_start_sb+0x38/0x1c0\n> [ 71.629383] mpage_prepare_extent_to_map+0x4af/0x580\n> [ 71.629389] ? sbitmap_get+0x73/0x180\n> [ 71.629399] ext4_do_writepages+0x3cc/0x10a0\n> [ 71.629400] ? kvm_sched_clock_read+0x11/0x20\n> [ 71.629409] ext4_writepages+0xc8/0x1b0\n> [ 71.629410] ? ext4_writepages+0xc8/0x1b0\n> [ 71.629411] do_writepages+0xc4/0x180\n> [ 71.629416] __writeback_single_inode+0x45/0x350\n> [ 71.629419] ? _raw_spin_unlock+0xe/0x40\n> [ 71.629423] writeback_sb_inodes+0x260/0x5c0\n> [ 71.629425] ? __schedule+0x4d1/0x1870\n> [ 71.629429] __writeback_inodes_wb+0x54/0x100\n> [ 71.629431] ? queue_io+0x82/0x140\n> [ 71.629433] wb_writeback+0x1ab/0x330\n> [ 71.629448] wb_workfn+0x31d/0x410\n> [ 71.629450] process_one_work+0x191/0x3e0\n> [ 71.629455] worker_thread+0x2e3/0x420\n>\n> [Fix]\n>\n> This upstream commit fixes the issue:\n> https://github.com/torvalds/linux/commit/f4a2b42e78914ff15630e71289adc589c3a8eb45\n>\n> All the discussions are in this thread:\n> https://lore.kernel.org/all/20260128074515.2028982-1-gerald.yang@canonical.com/\n>\n> [Test Plan]\n>\n> This can be easily reproduced by the following script:\n> mkdir -p mnt\n> dd if=/dev/zero of=ext4disk bs=1G count=2 oflag=direct\n> mkfs.ext4 ext4disk\n> tune2fs -o journal_data ext4disk\n> mount ext4disk mnt\n> fio --name=fiotest --rw=randwrite --bs=4k --runtime=3 --ioengine=libaio --iodepth=128 --numjobs=4 --filename=mnt/fiotest --filesize=1G --group_reporting\n> mount -o remount,ro ext4disk mnt\n> sync\n>\n> [Where problems could occur]\n>\n> When the call trace happens, there is no data lost, all the dirty data has been flushed to file system before remounting.\n> The fix is to make sure folio state is correct and update the xarray, so the writeback thread won't be trigger if there is no dirty data.\n> So if there is something really goes wrong, there still won't be data lost, even remount it to read-write mode again.\n>\n> Jan Kara (1):\n> ext4: fix stale xarray tags after writeback\n>\n> fs/ext4/page-io.c | 10 ++++++++--\n> 1 file changed, 8 insertions(+), 2 deletions(-)\n>\nAcked-by: Yufeng Gao ","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=aar5SFbB;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com\n (client-ip=185.125.189.65; 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charset=\"utf-8\"; Format=\"flowed\"","Errors-To":"kernel-team-bounces@lists.ubuntu.com","Sender":"\"kernel-team\" "}},{"id":3676115,"web_url":"http://patchwork.ozlabs.org/comment/3676115/","msgid":"<873412rqhm.fsf@gmail.com>","list_archive_url":null,"date":"2026-04-11T05:54:45","subject":"APPLIED: [SRU][N/Q][PATCH 0/1] Remount ext4 to readonly with\n data=journal mode may dump call trace","submitter":{"id":89305,"url":"http://patchwork.ozlabs.org/api/people/89305/","name":"Mehmet Basaran","email":"mehmet.basaran@canonical.com"},"content":"Applied to noble:linux, questing:linux master-next branches. Thanks.\nGerald Yang writes:\n\n> BugLink: https://bugs.launchpad.net/bugs/2147400\n>\n> [Impact]\n>\n> When journal is filled with some data and remount the filesystem to read-only in data=journal mode\n> it may dump the following call trace:\n> [ 71.629350] CPU: 0 UID: 0 PID: 177 Comm: kworker/u96:5 Tainted: G E 6.19.0-rc7 #1 PREEMPT(voluntary)\n> [ 71.629352] Tainted: [E]=UNSIGNED_MODULE\n> [ 71.629353] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009)/LXD, BIOS unknown 2/2/2022\n> [ 71.629354] Workqueue: writeback wb_workfn (flush-7:4)\n> [ 71.629359] RIP: 0010:ext4_journal_check_start+0x8b/0xd0\n> [ 71.629360] Code: 31 ff 45 31 c0 45 31 c9 e9 42 ad c4 00 48 8b 5d f8 b8 fb ff ff ff c9 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 c3 cc cc cc cc <0f> 0b b8 e2 ff ff ff eb c2 0f 0b eb\n> a9 44 8b 42 08 68 c7 53 ce b8\n> [ 71.629361] RSP: 0018:ffffcf32c0fdf6a8 EFLAGS: 00010202\n> [ 71.629364] RAX: ffff8f08c8505000 RBX: ffff8f08c67ee800 RCX: 0000000000000000\n> [ 71.629366] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000\n> [ 71.629367] RBP: ffffcf32c0fdf6b0 R08: 0000000000000001 R09: 0000000000000000\n> [ 71.629368] R10: ffff8f08db18b3a8 R11: 0000000000000000 R12: 0000000000000000\n> [ 71.629368] R13: 0000000000000002 R14: 0000000000000a48 R15: ffff8f08c67ee800\n> [ 71.629369] FS: 0000000000000000(0000) GS:ffff8f0a7d273000(0000) knlGS:0000000000000000\n> [ 71.629370] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n> [ 71.629371] CR2: 00007b66825905cc CR3: 000000011053d004 CR4: 0000000000772ef0\n> [ 71.629374] PKRU: 55555554\n> [ 71.629374] Call Trace:\n> [ 71.629378] \n> [ 71.629382] __ext4_journal_start_sb+0x38/0x1c0\n> [ 71.629383] mpage_prepare_extent_to_map+0x4af/0x580\n> [ 71.629389] ? sbitmap_get+0x73/0x180\n> [ 71.629399] ext4_do_writepages+0x3cc/0x10a0\n> [ 71.629400] ? kvm_sched_clock_read+0x11/0x20\n> [ 71.629409] ext4_writepages+0xc8/0x1b0\n> [ 71.629410] ? ext4_writepages+0xc8/0x1b0\n> [ 71.629411] do_writepages+0xc4/0x180\n> [ 71.629416] __writeback_single_inode+0x45/0x350\n> [ 71.629419] ? _raw_spin_unlock+0xe/0x40\n> [ 71.629423] writeback_sb_inodes+0x260/0x5c0\n> [ 71.629425] ? __schedule+0x4d1/0x1870\n> [ 71.629429] __writeback_inodes_wb+0x54/0x100\n> [ 71.629431] ? queue_io+0x82/0x140\n> [ 71.629433] wb_writeback+0x1ab/0x330\n> [ 71.629448] wb_workfn+0x31d/0x410\n> [ 71.629450] process_one_work+0x191/0x3e0\n> [ 71.629455] worker_thread+0x2e3/0x420\n>\n> [Fix]\n>\n> This upstream commit fixes the issue:\n> https://github.com/torvalds/linux/commit/f4a2b42e78914ff15630e71289adc589c3a8eb45\n>\n> All the discussions are in this thread:\n> https://lore.kernel.org/all/20260128074515.2028982-1-gerald.yang@canonical.com/\n>\n> [Test Plan]\n>\n> This can be easily reproduced by the following script:\n> mkdir -p mnt\n> dd if=/dev/zero of=ext4disk bs=1G count=2 oflag=direct\n> mkfs.ext4 ext4disk\n> tune2fs -o journal_data ext4disk\n> mount ext4disk mnt\n> fio --name=fiotest --rw=randwrite --bs=4k --runtime=3 --ioengine=libaio --iodepth=128 --numjobs=4 --filename=mnt/fiotest --filesize=1G --group_reporting\n> mount -o remount,ro ext4disk mnt\n> sync\n>\n> [Where problems could occur]\n>\n> When the call trace happens, there is no data lost, all the dirty data has been flushed to file system before remounting.\n> The fix is to make sure folio state is correct and update the xarray, so the writeback thread won't be trigger if there is no dirty data.\n> So if there is something really goes wrong, there still won't be data lost, even remount it to read-write mode again.\n>\n> Jan Kara (1):\n> ext4: fix stale xarray tags after writeback\n>\n> fs/ext4/page-io.c | 10 ++++++++--\n> 1 file changed, 8 insertions(+), 2 deletions(-)\n>\n> -- \n> 2.43.0\n>\n>\n> -- \n> kernel-team mailing list\n> kernel-team@lists.ubuntu.com\n> https://lists.ubuntu.com/mailman/listinfo/kernel-team","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=IORtHp6+;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com\n (client-ip=185.125.189.65; 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