* bcache: oops when writing to writeback_percent without a cache device
@ 2019-06-04 11:00 Bjørn Forsman
2019-06-04 14:59 ` Coly Li
0 siblings, 1 reply; 6+ messages in thread
From: Bjørn Forsman @ 2019-06-04 11:00 UTC (permalink / raw)
To: Coly Li, Kent Overstreet, linux-bcache, LKML
Hi all,
I get a kernel oops from bcache when writing to
/sys/block/bcache0/bcache/writeback_percent and there is no attached
cache device. See the oops itself below my signature.
This is on Linux 4.19.46. I looked in git and see many commits to
bcache lately, but none seem to address this particular issue.
Background: I'm writing to .../writeback_percent with
systemd-tmpfiles. I'd rather not replace it with a script that figures
out whether or not the kernel will oops if writing to the sysfs file
-- the kernel should not oops in the first place.
--
Best regards,
Bjørn Forsman
Jun 04 12:35:42 kernel: BUG: unable to handle kernel NULL pointer
dereference at 0000000000000340
Jun 04 12:35:42 kernel: PGD 0 P4D 0
Jun 04 12:35:42 kernel: Oops: 0000 [#1] SMP PTI
Jun 04 12:35:42 kernel: CPU: 6 PID: 20266 Comm: kworker/6:220 Not
tainted 4.19.46 #1-NixOS
Jun 04 12:35:42 kernel: Hardware name: To Be Filled By O.E.M. To Be
Filled By O.E.M./X99 Extreme4/3.1, BIOS P3.60 04/06/2018
Jun 04 12:35:42 kernel: Workqueue: events update_writeback_rate [bcache]
Jun 04 12:35:42 kernel: RIP: 0010:update_writeback_rate+0x2f/0x2e0 [bcache]
Jun 04 12:35:42 kernel: Code: 41 57 41 56 41 55 41 54 55 53 48 8b af
00 f4 ff ff f0 80 8f 20 f4 ff ff 10 f0 83 44 24 fc 00 48 8b 87 20 f4
ff ff a8 08 74 51 <48> 8b 85 40 03 00 00 a8 08 75 46 8b 47 e8 48 89 fb
85 c0 74 09 80
Jun 04 12:35:42 kernel: RSP: 0018:ffffafbfccdbbe68 EFLAGS: 00010202
Jun 04 12:35:42 kernel: RAX: 0000000000000018 RBX: ffff97bf75f60c80
RCX: ffff97bf7f9a0ee0
Jun 04 12:35:42 kernel: RDX: ffff97bf7f9a0ee0 RSI: 0000000000000180
RDI: ffff97bf75f60c80
Jun 04 12:35:42 kernel: RBP: 0000000000000000 R08: 000073746e657665
R09: 8080808080808080
Jun 04 12:35:42 kernel: R10: ffffafbfc3207de8 R11: fefefefefefefeff
R12: ffff97bf7f9a4d00
Jun 04 12:35:42 kernel: R13: 0000000000000000 R14: ffff97bf75270180
R15: 0ffff97bf7f9a4d0
Jun 04 12:35:42 kernel: FS: 0000000000000000(0000)
GS:ffff97bf7f980000(0000) knlGS:0000000000000000
Jun 04 12:35:42 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jun 04 12:35:42 kernel: CR2: 0000000000000340 CR3: 0000000709a0a004
CR4: 00000000001606e0
Jun 04 12:35:42 kernel: Call Trace:
Jun 04 12:35:42 kernel: process_one_work+0x1f4/0x3e0
Jun 04 12:35:42 kernel: worker_thread+0x2d/0x3e0
Jun 04 12:35:42 kernel: ? process_one_work+0x3e0/0x3e0
Jun 04 12:35:42 kernel: kthread+0x113/0x130
Jun 04 12:35:42 kernel: ? kthread_create_worker_on_cpu+0x70/0x70
Jun 04 12:35:42 kernel: ret_from_fork+0x35/0x40
Jun 04 12:35:42 kernel: Modules linked in: tcp_diag inet_diag
iptable_mangle xt_CHECKSUM ipt_MASQUERADE ipt_REJECT nf_reject_ipv4
bridge stp llc nf_tables nfnetlink devlink af_packet msr nouveau
edac_core x86_pkg_temp_thermal nls_iso8859_1 video intel_powerclamp
ttm nls_cp437 drm_kms_helper vfat coretemp drm fat crct10dif_pclmul
agpgart iptable_nat nf_nat_ipv4 nf_nat xt_conntrack crc32_pclmul
snd_hda_codec_hdmi nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
libcrc32c ip6t_rpfilter i2c_algo_bit ghash_clmulni_intel fb_sys_fops
syscopyarea ipt_rpfilter sysfillrect pcbc aesni_intel aes_x86_64
crypto_simd cryptd sysimgblt ip6table_raw iptable_raw
snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel xt_pkttype
glue_helper snd_hda_codec nf_log_ipv6 intel_cstate uas snd_hda_core
intel_uncore deflate e1000e snd_hwdep
Jun 04 12:35:42 kernel: snd_pcm iTCO_wdt joydev snd_timer mousedev
mxm_wmi intel_wmi_thunderbolt nf_log_ipv4 evdev input_leds led_class
snd nf_log_common xt_LOG efi_pstore intel_rapl_perf soundcore mac_hid
pstore xt_tcpudp efivars ptp nvme mei_me mei pps_core i2c_i801
nvme_core i2c_core lpc_ich wmi button ip6table_filter pcc_cpufreq
ip6_tables iptable_filter atkbd libps2 serio loop cpufreq_powersave
tun kvm_intel kvm irqbypass efivarfs ip_tables x_tables ipv6 crc_ccitt
autofs4 ext4 crc32c_generic crc16 mbcache jbd2 fscrypto usb_storage
bcache hid_logitech_hidpp crc64 raid1 md_mod hid_logitech_dj
hid_generic usbhid hid sd_mod xhci_pci ahci xhci_hcd libahci libata
ehci_pci ehci_hcd usbcore scsi_mod crc32c_intel usb_common rtc_cmos
dm_mod
Jun 04 12:35:42 kernel: CR2: 0000000000000340
Jun 04 12:35:42 kernel: ---[ end trace 764634a58d34fb7c ]---
Jun 04 12:35:43 kernel: RIP: 0010:update_writeback_rate+0x2f/0x2e0 [bcache]
Jun 04 12:35:43 kernel: Code: 41 57 41 56 41 55 41 54 55 53 48 8b af
00 f4 ff ff f0 80 8f 20 f4 ff ff 10 f0 83 44 24 fc 00 48 8b 87 20 f4
ff ff a8 08 74 51 <48> 8b 85 40 03 00 00 a8 08 75 46 8b 47 e8 48 89 fb
85 c0 74 09 80
Jun 04 12:35:43 kernel: RSP: 0018:ffffafbfccdbbe68 EFLAGS: 00010202
Jun 04 12:35:43 kernel: RAX: 0000000000000018 RBX: ffff97bf75f60c80
RCX: ffff97bf7f9a0ee0
Jun 04 12:35:43 kernel: RDX: ffff97bf7f9a0ee0 RSI: 0000000000000180
RDI: ffff97bf75f60c80
Jun 04 12:35:43 kernel: RBP: 0000000000000000 R08: 000073746e657665
R09: 8080808080808080
Jun 04 12:35:43 kernel: R10: ffffafbfc3207de8 R11: fefefefefefefeff
R12: ffff97bf7f9a4d00
Jun 04 12:35:43 kernel: R13: 0000000000000000 R14: ffff97bf75270180
R15: 0ffff97bf7f9a4d0
Jun 04 12:35:43 kernel: FS: 0000000000000000(0000)
GS:ffff97bf7f980000(0000) knlGS:0000000000000000
Jun 04 12:35:43 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jun 04 12:35:43 kernel: CR2: 0000000000000340 CR3: 0000000709a0a004
CR4: 00000000001606e0
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: bcache: oops when writing to writeback_percent without a cache device
2019-06-04 11:00 bcache: oops when writing to writeback_percent without a cache device Bjørn Forsman
@ 2019-06-04 14:59 ` Coly Li
2019-06-04 15:41 ` Coly Li
0 siblings, 1 reply; 6+ messages in thread
From: Coly Li @ 2019-06-04 14:59 UTC (permalink / raw)
To: Bjørn Forsman; +Cc: Kent Overstreet, linux-bcache, LKML
On 2019/6/4 7:00 下午, Bjørn Forsman wrote:
> Hi all,
>
> I get a kernel oops from bcache when writing to
> /sys/block/bcache0/bcache/writeback_percent and there is no attached
> cache device. See the oops itself below my signature.
>
> This is on Linux 4.19.46. I looked in git and see many commits to
> bcache lately, but none seem to address this particular issue.
>
> Background: I'm writing to .../writeback_percent with
> systemd-tmpfiles. I'd rather not replace it with a script that figures
> out whether or not the kernel will oops if writing to the sysfs file
> -- the kernel should not oops in the first place.
Hi Bjorn,
Thank you for the reporting. I believe this is a case we missed in
testings. When a bcache device is not attached, it does not make sense
to update the writeback rate in period by the changing of writeback_percent.
I will post a patch for your testing soon.
Coly Li
>
> Jun 04 12:35:42 kernel: BUG: unable to handle kernel NULL pointer
> dereference at 0000000000000340
> Jun 04 12:35:42 kernel: PGD 0 P4D 0
> Jun 04 12:35:42 kernel: Oops: 0000 [#1] SMP PTI
> Jun 04 12:35:42 kernel: CPU: 6 PID: 20266 Comm: kworker/6:220 Not
> tainted 4.19.46 #1-NixOS
> Jun 04 12:35:42 kernel: Hardware name: To Be Filled By O.E.M. To Be
> Filled By O.E.M./X99 Extreme4/3.1, BIOS P3.60 04/06/2018
> Jun 04 12:35:42 kernel: Workqueue: events update_writeback_rate [bcache]
> Jun 04 12:35:42 kernel: RIP: 0010:update_writeback_rate+0x2f/0x2e0 [bcache]
> Jun 04 12:35:42 kernel: Code: 41 57 41 56 41 55 41 54 55 53 48 8b af
> 00 f4 ff ff f0 80 8f 20 f4 ff ff 10 f0 83 44 24 fc 00 48 8b 87 20 f4
> ff ff a8 08 74 51 <48> 8b 85 40 03 00 00 a8 08 75 46 8b 47 e8 48 89 fb
> 85 c0 74 09 80
> Jun 04 12:35:42 kernel: RSP: 0018:ffffafbfccdbbe68 EFLAGS: 00010202
> Jun 04 12:35:42 kernel: RAX: 0000000000000018 RBX: ffff97bf75f60c80
> RCX: ffff97bf7f9a0ee0
> Jun 04 12:35:42 kernel: RDX: ffff97bf7f9a0ee0 RSI: 0000000000000180
> RDI: ffff97bf75f60c80
> Jun 04 12:35:42 kernel: RBP: 0000000000000000 R08: 000073746e657665
> R09: 8080808080808080
> Jun 04 12:35:42 kernel: R10: ffffafbfc3207de8 R11: fefefefefefefeff
> R12: ffff97bf7f9a4d00
> Jun 04 12:35:42 kernel: R13: 0000000000000000 R14: ffff97bf75270180
> R15: 0ffff97bf7f9a4d0
> Jun 04 12:35:42 kernel: FS: 0000000000000000(0000)
> GS:ffff97bf7f980000(0000) knlGS:0000000000000000
> Jun 04 12:35:42 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> Jun 04 12:35:42 kernel: CR2: 0000000000000340 CR3: 0000000709a0a004
> CR4: 00000000001606e0
> Jun 04 12:35:42 kernel: Call Trace:
> Jun 04 12:35:42 kernel: process_one_work+0x1f4/0x3e0
> Jun 04 12:35:42 kernel: worker_thread+0x2d/0x3e0
> Jun 04 12:35:42 kernel: ? process_one_work+0x3e0/0x3e0
> Jun 04 12:35:42 kernel: kthread+0x113/0x130
> Jun 04 12:35:42 kernel: ? kthread_create_worker_on_cpu+0x70/0x70
> Jun 04 12:35:42 kernel: ret_from_fork+0x35/0x40
> Jun 04 12:35:42 kernel: Modules linked in: tcp_diag inet_diag
> iptable_mangle xt_CHECKSUM ipt_MASQUERADE ipt_REJECT nf_reject_ipv4
> bridge stp llc nf_tables nfnetlink devlink af_packet msr nouveau
> edac_core x86_pkg_temp_thermal nls_iso8859_1 video intel_powerclamp
> ttm nls_cp437 drm_kms_helper vfat coretemp drm fat crct10dif_pclmul
> agpgart iptable_nat nf_nat_ipv4 nf_nat xt_conntrack crc32_pclmul
> snd_hda_codec_hdmi nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
> libcrc32c ip6t_rpfilter i2c_algo_bit ghash_clmulni_intel fb_sys_fops
> syscopyarea ipt_rpfilter sysfillrect pcbc aesni_intel aes_x86_64
> crypto_simd cryptd sysimgblt ip6table_raw iptable_raw
> snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel xt_pkttype
> glue_helper snd_hda_codec nf_log_ipv6 intel_cstate uas snd_hda_core
> intel_uncore deflate e1000e snd_hwdep
> Jun 04 12:35:42 kernel: snd_pcm iTCO_wdt joydev snd_timer mousedev
> mxm_wmi intel_wmi_thunderbolt nf_log_ipv4 evdev input_leds led_class
> snd nf_log_common xt_LOG efi_pstore intel_rapl_perf soundcore mac_hid
> pstore xt_tcpudp efivars ptp nvme mei_me mei pps_core i2c_i801
> nvme_core i2c_core lpc_ich wmi button ip6table_filter pcc_cpufreq
> ip6_tables iptable_filter atkbd libps2 serio loop cpufreq_powersave
> tun kvm_intel kvm irqbypass efivarfs ip_tables x_tables ipv6 crc_ccitt
> autofs4 ext4 crc32c_generic crc16 mbcache jbd2 fscrypto usb_storage
> bcache hid_logitech_hidpp crc64 raid1 md_mod hid_logitech_dj
> hid_generic usbhid hid sd_mod xhci_pci ahci xhci_hcd libahci libata
> ehci_pci ehci_hcd usbcore scsi_mod crc32c_intel usb_common rtc_cmos
> dm_mod
> Jun 04 12:35:42 kernel: CR2: 0000000000000340
> Jun 04 12:35:42 kernel: ---[ end trace 764634a58d34fb7c ]---
> Jun 04 12:35:43 kernel: RIP: 0010:update_writeback_rate+0x2f/0x2e0 [bcache]
> Jun 04 12:35:43 kernel: Code: 41 57 41 56 41 55 41 54 55 53 48 8b af
> 00 f4 ff ff f0 80 8f 20 f4 ff ff 10 f0 83 44 24 fc 00 48 8b 87 20 f4
> ff ff a8 08 74 51 <48> 8b 85 40 03 00 00 a8 08 75 46 8b 47 e8 48 89 fb
> 85 c0 74 09 80
> Jun 04 12:35:43 kernel: RSP: 0018:ffffafbfccdbbe68 EFLAGS: 00010202
> Jun 04 12:35:43 kernel: RAX: 0000000000000018 RBX: ffff97bf75f60c80
> RCX: ffff97bf7f9a0ee0
> Jun 04 12:35:43 kernel: RDX: ffff97bf7f9a0ee0 RSI: 0000000000000180
> RDI: ffff97bf75f60c80
> Jun 04 12:35:43 kernel: RBP: 0000000000000000 R08: 000073746e657665
> R09: 8080808080808080
> Jun 04 12:35:43 kernel: R10: ffffafbfc3207de8 R11: fefefefefefefeff
> R12: ffff97bf7f9a4d00
> Jun 04 12:35:43 kernel: R13: 0000000000000000 R14: ffff97bf75270180
> R15: 0ffff97bf7f9a4d0
> Jun 04 12:35:43 kernel: FS: 0000000000000000(0000)
> GS:ffff97bf7f980000(0000) knlGS:0000000000000000
> Jun 04 12:35:43 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> Jun 04 12:35:43 kernel: CR2: 0000000000000340 CR3: 0000000709a0a004
> CR4: 00000000001606e0
>
--
Coly Li
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: bcache: oops when writing to writeback_percent without a cache device
2019-06-04 14:59 ` Coly Li
@ 2019-06-04 15:41 ` Coly Li
2019-06-04 17:24 ` Bjørn Forsman
0 siblings, 1 reply; 6+ messages in thread
From: Coly Li @ 2019-06-04 15:41 UTC (permalink / raw)
To: Bjørn Forsman; +Cc: Kent Overstreet, linux-bcache, LKML
[-- Attachment #1: Type: text/plain, Size: 1651 bytes --]
On 2019/6/4 10:59 下午, Coly Li wrote:
> On 2019/6/4 7:00 下午, Bjørn Forsman wrote:
>> Hi all,
>>
>> I get a kernel oops from bcache when writing to
>> /sys/block/bcache0/bcache/writeback_percent and there is no attached
>> cache device. See the oops itself below my signature.
>>
>> This is on Linux 4.19.46. I looked in git and see many commits to
>> bcache lately, but none seem to address this particular issue.
>>
>> Background: I'm writing to .../writeback_percent with
>> systemd-tmpfiles. I'd rather not replace it with a script that figures
>> out whether or not the kernel will oops if writing to the sysfs file
>> -- the kernel should not oops in the first place.
>
> Hi Bjorn,
>
> Thank you for the reporting. I believe this is a case we missed in
> testings. When a bcache device is not attached, it does not make sense
> to update the writeback rate in period by the changing of writeback_percent.
>
> I will post a patch for your testing soon.
Hi Bjorn,
Could you please to try this patch ? Hope it may help a bit.
Thanks.
Coly Li
>>
>> Jun 04 12:35:42 kernel: BUG: unable to handle kernel NULL pointer
>> dereference at 0000000000000340
>> Jun 04 12:35:42 kernel: PGD 0 P4D 0
>> Jun 04 12:35:42 kernel: Oops: 0000 [#1] SMP PTI
>> Jun 04 12:35:42 kernel: CPU: 6 PID: 20266 Comm: kworker/6:220 Not
>> tainted 4.19.46 #1-NixOS
>> Jun 04 12:35:42 kernel: Hardware name: To Be Filled By O.E.M. To Be
>> Filled By O.E.M./X99 Extreme4/3.1, BIOS P3.60 04/06/2018
>> Jun 04 12:35:42 kernel: Workqueue: events update_writeback_rate [bcache]
>> Jun 04 12:35:42 kernel: RIP: 0010:update_writeback_rate+0x2f/0x2e0 [bcache]
[snipped]
[-- Attachment #2: 0001-bcache-only-set-BCACHE_DEV_WB_RUNNING-when-cached-de.patch --]
[-- Type: text/plain, Size: 1830 bytes --]
From 9dea1e6ad0e6c40e3bc6ee6cf4ad243c07ca6ca9 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Tue, 4 Jun 2019 23:24:09 +0800
Subject: [PATCH] bcache: only set BCACHE_DEV_WB_RUNNING when cached device
attached
When people set a writeback percent via sysfs file,
/sys/block/bcache<N>/bcache/writeback_percent
current code directly sets BCACHE_DEV_WB_RUNNING to dc->disk.flags
and schedules kworker dc->writeback_rate_update.
If there is no cache set attached to, the writebac kernel thread is
not running indeed, running dc->writeback_rate_update does not make
sense and may cause NULL pointer deference when reference cache set
pointer inside update_writeback_rate().
This patch checks whether the cache set point (dc->disk.c) is NULL in
sysfs interface handler, and only set BCACHE_DEV_WB_RUNNING and
schedule dc->writeback_rate_update when dc->disk.c is not NULL (it
means the cache device is attached to a cache set).
Reported-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/bcache/sysfs.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 129031663cc8..eb678e43ac00 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -430,8 +430,13 @@ STORE(bch_cached_dev)
bch_writeback_queue(dc);
}
+ /*
+ * Only set BCACHE_DEV_WB_RUNNING when cached device attached to
+ * a cache set, otherwise it doesn't make sense.
+ */
if (attr == &sysfs_writeback_percent)
- if (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
+ if ((dc->disk.c != NULL) &&
+ (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)))
schedule_delayed_work(&dc->writeback_rate_update,
dc->writeback_rate_update_seconds * HZ);
--
2.16.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: bcache: oops when writing to writeback_percent without a cache device
2019-06-04 15:41 ` Coly Li
@ 2019-06-04 17:24 ` Bjørn Forsman
2019-06-05 4:41 ` Coly Li
0 siblings, 1 reply; 6+ messages in thread
From: Bjørn Forsman @ 2019-06-04 17:24 UTC (permalink / raw)
To: Coly Li; +Cc: Kent Overstreet, linux-bcache, LKML
On Tue, 4 Jun 2019 at 17:41, Coly Li <colyli@suse.de> wrote:
>
> On 2019/6/4 10:59 下午, Coly Li wrote:
> > On 2019/6/4 7:00 下午, Bjørn Forsman wrote:
> >> Hi all,
> >>
> >> I get a kernel oops from bcache when writing to
> >> /sys/block/bcache0/bcache/writeback_percent and there is no attached
> >> cache device. See the oops itself below my signature.
> >>
> >> This is on Linux 4.19.46. I looked in git and see many commits to
> >> bcache lately, but none seem to address this particular issue.
> >>
> >> Background: I'm writing to .../writeback_percent with
> >> systemd-tmpfiles. I'd rather not replace it with a script that figures
> >> out whether or not the kernel will oops if writing to the sysfs file
> >> -- the kernel should not oops in the first place.
> >
> > Hi Bjorn,
> >
> > Thank you for the reporting. I believe this is a case we missed in
> > testings. When a bcache device is not attached, it does not make sense
> > to update the writeback rate in period by the changing of writeback_percent.
> >
> > I will post a patch for your testing soon.
>
> Hi Bjorn,
>
> Could you please to try this patch ? Hope it may help a bit.
Hi Coly,
Thanks for the quick patch! I tested it on linux 5.2-rc2 and it indeed
fixes the problem.
There is one typo in the patch/commit message: s/writebac/writeback/
--
Best regards,
Bjørn Forsman
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: bcache: oops when writing to writeback_percent without a cache device
2019-06-04 17:24 ` Bjørn Forsman
@ 2019-06-05 4:41 ` Coly Li
2019-06-05 9:21 ` Bjørn Forsman
0 siblings, 1 reply; 6+ messages in thread
From: Coly Li @ 2019-06-05 4:41 UTC (permalink / raw)
To: Bjørn Forsman; +Cc: Kent Overstreet, linux-bcache, LKML
On 2019/6/5 1:24 上午, Bjørn Forsman wrote:
> On Tue, 4 Jun 2019 at 17:41, Coly Li <colyli@suse.de> wrote:
>>
>> On 2019/6/4 10:59 下午, Coly Li wrote:
>>> On 2019/6/4 7:00 下午, Bjørn Forsman wrote:
>>>> Hi all,
>>>>
>>>> I get a kernel oops from bcache when writing to
>>>> /sys/block/bcache0/bcache/writeback_percent and there is no attached
>>>> cache device. See the oops itself below my signature.
>>>>
>>>> This is on Linux 4.19.46. I looked in git and see many commits to
>>>> bcache lately, but none seem to address this particular issue.
>>>>
>>>> Background: I'm writing to .../writeback_percent with
>>>> systemd-tmpfiles. I'd rather not replace it with a script that figures
>>>> out whether or not the kernel will oops if writing to the sysfs file
>>>> -- the kernel should not oops in the first place.
>>>
>>> Hi Bjorn,
>>>
>>> Thank you for the reporting. I believe this is a case we missed in
>>> testings. When a bcache device is not attached, it does not make sense
>>> to update the writeback rate in period by the changing of writeback_percent.
>>>
>>> I will post a patch for your testing soon.
>>
>> Hi Bjorn,
>>
>> Could you please to try this patch ? Hope it may help a bit.
>
> Hi Coly,
>
> Thanks for the quick patch! I tested it on linux 5.2-rc2 and it indeed
> fixes the problem.
>
> There is one typo in the patch/commit message: s/writebac/writeback/
>
Hi Bjorn,
Thanks for the patch review. Do you mind if I add Reviewed-By: tag with
your name and email address ?
--
Coly Li
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: bcache: oops when writing to writeback_percent without a cache device
2019-06-05 4:41 ` Coly Li
@ 2019-06-05 9:21 ` Bjørn Forsman
0 siblings, 0 replies; 6+ messages in thread
From: Bjørn Forsman @ 2019-06-05 9:21 UTC (permalink / raw)
To: Coly Li; +Cc: Kent Overstreet, linux-bcache, LKML
On Wed, 5 Jun 2019 at 06:41, Coly Li <colyli@suse.de> wrote:
>
> On 2019/6/5 1:24 上午, Bjørn Forsman wrote:
> > On Tue, 4 Jun 2019 at 17:41, Coly Li <colyli@suse.de> wrote:
> >>
> >> On 2019/6/4 10:59 下午, Coly Li wrote:
> >>> On 2019/6/4 7:00 下午, Bjørn Forsman wrote:
> >>>> Hi all,
> >>>>
> >>>> I get a kernel oops from bcache when writing to
> >>>> /sys/block/bcache0/bcache/writeback_percent and there is no attached
> >>>> cache device. See the oops itself below my signature.
> >>>>
> >>>> This is on Linux 4.19.46. I looked in git and see many commits to
> >>>> bcache lately, but none seem to address this particular issue.
> >>>>
> >>>> Background: I'm writing to .../writeback_percent with
> >>>> systemd-tmpfiles. I'd rather not replace it with a script that figures
> >>>> out whether or not the kernel will oops if writing to the sysfs file
> >>>> -- the kernel should not oops in the first place.
> >>>
> >>> Hi Bjorn,
> >>>
> >>> Thank you for the reporting. I believe this is a case we missed in
> >>> testings. When a bcache device is not attached, it does not make sense
> >>> to update the writeback rate in period by the changing of writeback_percent.
> >>>
> >>> I will post a patch for your testing soon.
> >>
> >> Hi Bjorn,
> >>
> >> Could you please to try this patch ? Hope it may help a bit.
> >
> > Hi Coly,
> >
> > Thanks for the quick patch! I tested it on linux 5.2-rc2 and it indeed
> > fixes the problem.
> >
> > There is one typo in the patch/commit message: s/writebac/writeback/
> >
>
> Hi Bjorn,
>
> Thanks for the patch review. Do you mind if I add Reviewed-By: tag with
> your name and email address ?
Yes, you can add my Reviewed-By: tag.
--
Bjørn Forsman
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-06-05 9:22 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-04 11:00 bcache: oops when writing to writeback_percent without a cache device Bjørn Forsman
2019-06-04 14:59 ` Coly Li
2019-06-04 15:41 ` Coly Li
2019-06-04 17:24 ` Bjørn Forsman
2019-06-05 4:41 ` Coly Li
2019-06-05 9:21 ` Bjørn Forsman
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