Date:   Wed, 11 May 2022 17:30:14 +0200
From:   Wolfgang Walter <linux@...m.de>
To:     Chuck Lever III <chuck.lever@...cle.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        linux-stable <stable@...r.kernel.org>,
        Trond Myklebust <trondmy@...il.com>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: 5.4.188 and later: massive performance regression with nfsd

Am 2022-05-11 16:36, schrieb Chuck Lever III:
>> On May 11, 2022, at 10:23 AM, Greg KH <gregkh@...uxfoundation.org> 
>> wrote:
>> 
>> On Wed, May 11, 2022 at 02:16:19PM +0000, Chuck Lever III wrote:
>>> 
>>> 
>>>> On May 11, 2022, at 8:38 AM, Greg KH <gregkh@...uxfoundation.org> 
>>>> wrote:
>>>> 
>>>> On Wed, May 11, 2022 at 12:03:13PM +0200, Wolfgang Walter wrote:
>>>>> Hi,
>>>>> 
>>>>> starting with 5.4.188 wie see a massive performance regression on 
>>>>> our
>>>>> nfs-server. It basically is serving requests very very slowly with 
>>>>> cpu
>>>>> utilization of 100% (with 5.4.187 and earlier it is 10%) so that it 
>>>>> is
>>>>> unusable as a fileserver.
>>>>> 
>>>>> The culprit are commits (or one of it):
>>>>> 
>>>>> c32f1041382a88b17da5736886da4a492353a1bb "nfsd: cleanup
>>>>> nfsd_file_lru_dispose()"
>>>>> 628adfa21815f74c04724abc85847f24b5dd1645 "nfsd: Containerise 
>>>>> filecache
>>>>> laundrette"
>>>>> 
>>>>> (upstream 36ebbdb96b694dd9c6b25ad98f2bbd263d022b63 and
>>>>> 9542e6a643fc69d528dfb3303f145719c61d3050)
>>>>> 
>>>>> If I revert them in v5.4.192 the kernel works as before and 
>>>>> performance is
>>>>> ok again.
>>>>> 
>>>>> I did not try to revert them one by one as any disruption of our 
>>>>> nfs-server
>>>>> is a severe problem for us and I'm not sure if they are related.
>>>>> 
>>>>> 5.10 and 5.15 both always performed very badly on our nfs-server in 
>>>>> a
>>>>> similar way so we were stuck with 5.4.
>>>>> 
>>>>> I now think this is because of 
>>>>> 36ebbdb96b694dd9c6b25ad98f2bbd263d022b63
>>>>> and/or 9542e6a643fc69d528dfb3303f145719c61d3050 though I didn't 
>>>>> tried to
>>>>> revert them in 5.15 yet.
>>>> 
>>>> Odds are 5.18-rc6 is also a problem?
>>> 
>>> We believe that
>>> 
>>> 6b8a94332ee4 ("nfsd: Fix a write performance regression")
>>> 
>>> addresses the performance regression. It was merged into 5.18-rc.
>> 
>> And into 5.17.4 if someone wants to try that release.
> 
> I don't have a lot of time to backport this one myself, so
> I welcome anyone who wants to apply that commit to their
> favorite LTS kernel and test it for us.
> 
> 
>>>> If so, I'll just wait for the fix to get into Linus's tree as this 
>>>> does
>>>> not seem to be a stable-tree-only issue.
>>> 
>>> Unfortunately I've received a recent report that the fix introduces
>>> a "sleep while spinlock is held" for NFSv4.0 in rare cases.
>> 
>> Ick, not good, any potential fixes for that?
> 
> Not yet. I was at LSF last week, so I've just started digging
> into this one. I've confirmed that the report is a real bug,
> but we still don't know how hard it is to hit it with real
> workloads.
> 
> 
> --
> Chuck Lever

This maybe unrelated: when I used 5.4.188 for the first time I got this:

[Mon Apr 11 09:20:23 2022] ------------[ cut here ]------------
[Mon Apr 11 09:20:23 2022] refcount_t: underflow; use-after-free.
[Mon Apr 11 09:20:23 2022] WARNING: CPU: 18 PID: 7443 at 
lib/refcount.c:190 refcount_sub_and_test_checked+0x48/0x50
[Mon Apr 11 09:20:23 2022] Modules linked in: rpcsec_gss_krb5(E) msr(E) 
8021q(E) garp(E) stp(E) mrp(E) llc(E) dm_cache_smq(E) binfmt_misc(E) 
dm_cache(E) dm_persistent_data(E) dm_bio_prison(E) dm_bufio(E) 
ipmi_ssif(E) intel_rapl_ms
r(E) intel_rapl_common(E) sb_edac(E) x86_pkg_temp_thermal(E) 
intel_powerclamp(E) coretemp(E) kvm_intel(E) kvm(E) irqbypass(E) 
crct10dif_pclmul(E) crc32_pclmul(E) ast(E) snd_pcm(E) drm_vram_helper(E) 
ttm(E) ghash_clmulni_intel(E) s
nd_timer(E) rapl(E) snd(E) soundcore(E) drm_kms_helper(E) 
intel_cstate(E) pcspkr(E) iTCO_wdt(E) intel_uncore(E) drm(E) 
iTCO_vendor_support(E) mei_me(E) joydev(E) i2c_algo_bit(E) watchdog(E) 
mei(E) ioatdma(E) evdev(E) sg(E) ipmi_si
(E) ipmi_devintf(E) ipmi_msghandler(E) acpi_power_meter(E) acpi_pad(E) 
button(E) poly1305_x86_64(E) poly1305_generic(E) sha256_ssse3(E) 
sha1_ssse3(E) chacha_generic(E) chacha20poly1305(E) aesni_intel(E) 
crypto_simd(E) glue_helper(
E) cryptd(E) drbd(E) lru_cache(E) nfsd(E) nfs_acl(E) lockd(E) grace(E) 
auth_rpcgss(E) sunrpc(E)
[Mon Apr 11 09:20:23 2022]  ip_tables(E) x_tables(E) autofs4(E) ext4(E) 
crc16(E) mbcache(E) jbd2(E) dm_mod(E) raid10(E) raid456(E) 
async_raid6_recov(E) async_memcpy(E) async_pq(E) async_xor(E) 
async_tx(E) xor(E) raid6_pq(E) libcrc
32c(E) crc32c_generic(E) raid0(E) multipath(E) linear(E) ses(E) 
enclosure(E) hid_generic(E) usbhid(E) hid(E) raid1(E) md_mod(E) 
sd_mod(E) crc32c_intel(E) ixgbe(E) ahci(E) xhci_pci(E) libahci(E) 
ehci_pci(E) xfrm_algo(E) mpt3sas(E)
xhci_hcd(E) ehci_hcd(E) dca(E) raid_class(E) libata(E) libphy(E) 
usbcore(E) scsi_transport_sas(E) lpc_ich(E) ptp(E) i2c_i801(E) 
mfd_core(E) usb_common(E) pps_core(E) scsi_mod(E) mdio(E) wmi(E)
[Mon Apr 11 09:20:23 2022] CPU: 18 PID: 7443 Comm: kworker/u50:1 
Tainted: G        W   E     5.4.188-debian64.all+1.2 #1
[Mon Apr 11 09:20:23 2022] Hardware name: Supermicro X10DRi/X10DRI-T, 
BIOS 1.1a 10/16/2015
[Mon Apr 11 09:20:23 2022] Workqueue: rpciod rpc_async_schedule [sunrpc]
[Mon Apr 11 09:20:23 2022] RIP: 
0010:refcount_sub_and_test_checked+0x48/0x50
[Mon Apr 11 09:20:23 2022] Code: 31 e4 44 89 e0 41 5c c3 eb f8 44 0f b6 
25 7c ee ce 00 45 84 e4 75 e8 48 c7 c7 80 97 8b b1 c6 05 69 ee ce 00 01 
e8 78 3f 3a 00 <0f> 0b eb d4 0f 1f 40 00 48 89 fe bf 01 00 00 00 eb a6 
66 0f 1f 44
[Mon Apr 11 09:20:23 2022] RSP: 0018:ffffad8a8d01fe48 EFLAGS: 00010286
[Mon Apr 11 09:20:23 2022] RAX: 0000000000000000 RBX: 0000000000002a81 
RCX: 0000000000000000
[Mon Apr 11 09:20:23 2022] RDX: 0000000000000001 RSI: 0000000000000082 
RDI: 00000000ffffffff
[Mon Apr 11 09:20:23 2022] RBP: ffff9fb4a2394400 R08: 0000000000000001 
R09: 000000000000085b
[Mon Apr 11 09:20:23 2022] R10: 0000000000030f5c R11: 0000000000000004 
R12: 0000000000000000
[Mon Apr 11 09:20:23 2022] R13: ffff9feaf358d400 R14: 0000000000000000 
R15: ffff9fb7e1b25148
[Mon Apr 11 09:20:23 2022] FS:  0000000000000000(0000) 
GS:ffff9feaff980000(0000) knlGS:0000000000000000
[Mon Apr 11 09:20:23 2022] CS:  0010 DS: 0000 ES: 0000 CR0: 
0000000080050033
[Mon Apr 11 09:20:23 2022] CR2: 00007ffe62ca3080 CR3: 000000350880a002 
CR4: 00000000001606e0
[Mon Apr 11 09:20:23 2022] Call Trace:
[Mon Apr 11 09:20:23 2022]  nfsd4_cb_offload_release+0x16/0x30 [nfsd]
[Mon Apr 11 09:20:23 2022]  rpc_free_task+0x39/0x70 [sunrpc]
[Mon Apr 11 09:20:23 2022]  rpc_async_schedule+0x29/0x40 [sunrpc]
[Mon Apr 11 09:20:23 2022]  process_one_work+0x1ab/0x390
[Mon Apr 11 09:20:23 2022]  worker_thread+0x50/0x3c0
[Mon Apr 11 09:20:23 2022]  ? rescuer_thread+0x370/0x370
[Mon Apr 11 09:20:23 2022]  kthread+0x13c/0x160
[Mon Apr 11 09:20:23 2022]  ? __kthread_bind_mask+0x60/0x60
[Mon Apr 11 09:20:23 2022]  ret_from_fork+0x1f/0x40
[Mon Apr 11 09:20:23 2022] ---[ end trace c58c1aaca9be5d21 ]---
[Mon Apr 11 09:56:32 2022] perf: interrupt took too long (6293 > 6228), 
lowering kernel.perf_event_max_sample_rate to 31750
[Mon Apr 11 09:59:17 2022] ------------[ cut here ]------------

[Mon Apr 11 09:59:17 2022] nfsd4_process_open2 failed to open 
newly-created file! status=10008
[Mon Apr 11 09:59:17 2022] WARNING: CPU: 2 PID: 3061 at 
fs/nfsd/nfs4proc.c:456 nfsd4_open+0x39a/0x710 [nfsd]
[Mon Apr 11 09:59:17 2022] Modules linked in: rpcsec_gss_krb5(E) msr(E) 
8021q(E) garp(E) stp(E) mrp(E) llc(E) dm_cache_smq(E) binfmt_misc(E) 
dm_cache(E) dm_persistent_data(E) dm_bio_prison(E) dm_bufio(E) 
ipmi_ssif(E) intel_rapl_msr(E) intel_rapl_common(E) sb_edac(E) 
x86_pkg_temp_thermal(E) intel_powerclamp(E) coretemp(E) kvm_intel(E) 
kvm(E) irqbypass(E) crct10dif_pclmul(E) crc32_pclmul(E) ast(E) 
snd_pcm(E) drm_vram_helper(E) ttm(E) ghash_clmulni_intel(E) snd_timer(E) 
rapl(E) snd(E) soundcore(E) drm_kms_helper(E) intel_cstate(E) pcspkr(E) 
iTCO_wdt(E) intel_uncore(E) drm(E) iTCO_vendor_support(E) mei_me(E) 
joydev(E) i2c_algo_bit(E) watchdog(E) mei(E) ioatdma(E) evdev(E) sg(E) 
ipmi_si(E) ipmi_devintf(E) ipmi_msghandler(E) acpi_power_meter(E) 
acpi_pad(E) button(E) poly1305_x86_64(E) poly1305_generic(E) 
sha256_ssse3(E) sha1_ssse3(E) chacha_generic(E) chacha20poly1305(E) 
aesni_intel(E) crypto_simd(E) glue_helper(E) cryptd(E) drbd(E) 
lru_cache(E) nfsd(E) nfs_acl(E) lockd(E) grace(E) auth_rpcgss(E) 
sunrpc(E)
[Mon Apr 11 09:59:17 2022]  ip_tables(E) x_tables(E) autofs4(E) ext4(E) 
crc16(E) mbcache(E) jbd2(E) dm_mod(E) raid10(E) raid456(E) 
async_raid6_recov(E) async_memcpy(E) async_pq(E) async_xor(E) 
async_tx(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) raid0(E) 
multipath(E) linear(E) ses(E) enclosure(E) hid_generic(E) usbhid(E) 
hid(E) raid1(E) md_mod(E) sd_mod(E) crc32c_intel(E) ixgbe(E) ahci(E) 
xhci_pci(E) libahci(E) ehci_pci(E) xfrm_algo(E) mpt3sas(E) xhci_hcd(E) 
ehci_hcd(E) dca(E) raid_class(E) libata(E) libphy(E) usbcore(E) 
scsi_transport_sas(E) lpc_ich(E) ptp(E) i2c_i801(E) mfd_core(E) 
usb_common(E) pps_core(E) scsi_mod(E) mdio(E) wmi(E)
[Mon Apr 11 09:59:17 2022] CPU: 2 PID: 3061 Comm: nfsd Tainted: G        
W   E     5.4.188-debian64.all+1.2 #1
[Mon Apr 11 09:59:17 2022] Hardware name: Supermicro X10DRi/X10DRI-T, 
BIOS 1.1a 10/16/2015
[Mon Apr 11 09:59:17 2022] RIP: 0010:nfsd4_open+0x39a/0x710 [nfsd]
[Mon Apr 11 09:59:17 2022] Code: e8 db 0f 01 00 41 89 c5 85 c0 0f 84 5e 
01 00 00 80 bd 15 01 00 00 00 74 13 44 89 ee 48 c7 c7 a8 08 6f c0 0f ce 
e8 b6 f8 ae f0 <0f> 0b 4d 85 ff 0f 84 58 fd ff ff 4d 39 fc 0f 84 4f fd 
ff ff 4c 89
[Mon Apr 11 09:59:17 2022] RSP: 0018:ffffad8ab09c7db8 EFLAGS: 00010286
[Mon Apr 11 09:59:17 2022] RAX: 0000000000000000 RBX: ffff9feaaf7cb000 
RCX: 0000000000000000
[Mon Apr 11 09:59:17 2022] RDX: 0000000000000001 RSI: 0000000000000082 
RDI: 00000000ffffffff
[Mon Apr 11 09:59:17 2022] RBP: ffff9feaae54f460 R08: 0000000000000001 
R09: 000000000000087a
[Mon Apr 11 09:59:17 2022] R10: 0000000000031e00 R11: 0000000000000004 
R12: ffff9feaae550070
[Mon Apr 11 09:59:17 2022] R13: 0000000018270000 R14: ffff9feaae5ae000 
R15: ffff9fc07ccfd400
[Mon Apr 11 09:59:17 2022] FS:  0000000000000000(0000) 
GS:ffff9fcb1f880000(0000) knlGS:0000000000000000
[Mon Apr 11 09:59:17 2022] CS:  0010 DS: 0000 ES: 0000 CR0: 
0000000080050033
[Mon Apr 11 09:59:17 2022] CR2: 00007fdae60db000 CR3: 00000037e87fe005 
CR4: 00000000001606e0
[Mon Apr 11 09:59:17 2022] Call Trace:
[Mon Apr 11 09:59:17 2022]  nfsd4_proc_compound+0x45d/0x730 [nfsd]
[Mon Apr 11 09:59:17 2022]  nfsd_dispatch+0xc1/0x200 [nfsd]
[Mon Apr 11 09:59:17 2022]  svc_process_common+0x399/0x6e0 [sunrpc]
[Mon Apr 11 09:59:17 2022]  ? svc_recv+0x312/0x9f0 [sunrpc]
[Mon Apr 11 09:59:17 2022]  ? nfsd_svc+0x2f0/0x2f0 [nfsd]
[Mon Apr 11 09:59:17 2022]  ? nfsd_destroy+0x60/0x60 [nfsd]
[Mon Apr 11 09:59:17 2022]  svc_process+0xd4/0x110 [sunrpc]
[Mon Apr 11 09:59:17 2022]  nfsd+0xed/0x150 [nfsd]
[Mon Apr 11 09:59:17 2022]  kthread+0x13c/0x160
[Mon Apr 11 09:59:17 2022]  ? __kthread_bind_mask+0x60/0x60
[Mon Apr 11 09:59:17 2022]  ret_from_fork+0x1f/0x40
[Mon Apr 11 09:59:17 2022] ---[ end trace c58c1aaca9be5d22 ]---

I never saw this with an earlier kernel (and we use 5.4 since a long 
time).

I did not see this with the unchanged 5.4.192, though, which I tested 
before running 5.4.192 with the above mentioned patches reverted.

Regards,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts

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