Date: Tue, 21 May 2024 08:58:56 +0800
From: Zhaoyang Huang <huangzhaoyang@...il.com>
To: Marcin Wanat <private@...cinwanat.pl>
Cc: Dave Chinner <david@...morbit.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	"zhaoyang.huang" <zhaoyang.huang@...soc.com>, Alex Shi <alexs@...nel.org>, 
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Hugh Dickins <hughd@...gle.com>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, steve.kang@...soc.com
Subject: Re: [PATCH 1/1] mm: protect xa split stuff under lruvec->lru_lock
 during migration

On Tue, May 21, 2024 at 3:42 AM Marcin Wanat <private@...cinwanat.pl> wrote:
>
> On 15.04.2024 03:50, Zhaoyang Huang wrote:
> > On Mon, Apr 15, 2024 at 8:09 AM Dave Chinner <david@...morbit.com> > wrote: >> >> On Sat, Apr 13, 2024 at 10:01:27AM +0800, Zhaoyang
> Huang wrote: >>> loop Dave, since he has ever helped set up an
> reproducer in >>> https://lore.kernel.org/linux- >>>
> mm/20221101071721.GV2703033@...ad.disaster.area/ @Dave Chinner , >>> I
> would like to ask for your kindly help on if you can verify >>> this
> patch on your environment if convenient. Thanks a lot. >> >> I don't
> have the test environment from 18 months ago available any >> more.
> Also, I haven't seen this problem since that specific test >>
> environment tripped over the issue. Hence I don't have any way of >>
> confirming that the problem is fixed, either, because first I'd >> have
> to reproduce it... > Thanks for the information. I noticed that you
> reported another soft > lockup which is related to xas_load since
> NOV.2023. This patch is > supposed to be helpful for this. With regard
> to the version timing, > this commit is actually a revert of <mm/thp:
> narrow lru locking> > b6769834aac1d467fa1c71277d15688efcbb4d76 which is
> merged before > v5.15. > > For saving your time, a brief description
> below. IMO, b6769834aa > introduce a potential stall between freeze the
> folio's refcnt and > store it back to 2, which have the
> xas_load->folio_try_get_rcu loops > as livelock if it stalls the
> lru_lock's holder. > > b6769834aa split_huge_page_to_list -
> spin_lock(lru_lock) > xas_split(&xas, folio,order)
> folio_refcnt_freeze(folio, 1 + > folio_nr_pages(folio0) +
> spin_lock(lru_lock) xas_store(&xas, > offset++, head+i)
> page_ref_add(head, 2) spin_unlock(lru_lock) > > Sorry in advance if the
> above doesn't make sense, I am just a > developer who is also suffering
> from this bug and trying to fix it
> I am experiencing a similar error on dozens of hosts, with stack traces
> that are all similar:
>
> [627163.727746] watchdog: BUG: soft lockup - CPU#77 stuck for 22s!
> [file_get:953301]
> [627163.727778] Modules linked in: xt_set ip_set_hash_net ip_set xt_CT
> xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat
> nf_tables nfnetlink sr_mod cdrom rfkill vfat fat intel_rapl_msr
> intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common
> isst_if_common skx_edac nfit libnvdimm x86_pkg_temp_thermal
> intel_powerclamp coretemp ipmi_ssif kvm_intel kvm irqbypass mlx5_ib rapl
> iTCO_wdt intel_cstate intel_pmc_bxt ib_uverbs iTCO_vendor_support
> dell_smbios dcdbas i2c_i801 intel_uncore uas ses mei_me ib_core
> dell_wmi_descriptor wmi_bmof pcspkr enclosure lpc_ich usb_storage
> i2c_smbus acpi_ipmi mei intel_pch_thermal ipmi_si ipmi_devintf
> ipmi_msghandler acpi_power_meter joydev tcp_bbr fuse xfs libcrc32c raid1
> sd_mod sg mlx5_core crct10dif_pclmul crc32_pclmul crc32c_intel
> polyval_clmulni mgag200 polyval_generic drm_kms_helper mlxfw
> drm_shmem_helper ahci nvme mpt3sas tls libahci ghash_clmulni_intel
> nvme_core psample drm igb t10_pi raid_class pci_hyperv_intf dca libata
> scsi_transport_sas i2c_algo_bit wmi
> [627163.727841] CPU: 77 PID: 953301 Comm: file_get Kdump: loaded
> Tainted: G             L     6.6.30.el9 #2
> [627163.727844] Hardware name: Dell Inc. PowerEdge R740xd/08D89F, BIOS
> 2.21.2 02/19/2024
> [627163.727847] RIP: 0010:xas_descend+0x1b/0x70
> [627163.727857] Code: 57 10 48 89 07 48 c1 e8 20 48 89 57 08 c3 cc 0f b6
> 0e 48 8b 47 08 48 d3 e8 48 89 c1 83 e1 3f 89 c8 48 83 c0 04 48 8b 44 c6
> 08 <48> 89 77 18 48 89 c2 83 e2 03 48 83 fa 02 74 0a 88 4f 12 c3 48 83
> [627163.727859] RSP: 0018:ffffc90034a67978 EFLAGS: 00000206
> [627163.727861] RAX: ffff888e4f971242 RBX: ffffc90034a67a98 RCX:
> 0000000000000020
> [627163.727863] RDX: 0000000000000002 RSI: ffff88a454546d80 RDI:
> ffffc90034a67990
> [627163.727865] RBP: fffffffffffffffe R08: fffffffffffffffe R09:
> 0000000000008820
> [627163.727867] R10: 0000000000008820 R11: 0000000000000000 R12:
> ffffc90034a67a20
> [627163.727868] R13: ffffc90034a67a18 R14: ffffea00873e8000 R15:
> ffffc90034a67a18
> [627163.727870] FS:  00007fc5e503b740(0000) GS:ffff88bfefd80000(0000)
> knlGS:0000000000000000
> [627163.727871] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [627163.727873] CR2: 000000005fb87b6e CR3: 00000022875e8006 CR4:
> 00000000007706e0
> [627163.727875] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [627163.727876] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
> 0000000000000400
> [627163.727878] PKRU: 55555554
> [627163.727879] Call Trace:
> [627163.727882]  <IRQ>
> [627163.727886]  ? watchdog_timer_fn+0x22a/0x2a0
> [627163.727892]  ? softlockup_fn+0x70/0x70
> [627163.727895]  ? __hrtimer_run_queues+0x10f/0x2a0
> [627163.727903]  ? hrtimer_interrupt+0x106/0x240
> [627163.727906]  ? __sysvec_apic_timer_interrupt+0x68/0x170
> [627163.727913]  ? sysvec_apic_timer_interrupt+0x9d/0xd0
> [627163.727917]  </IRQ>
> [627163.727918]  <TASK>
> [627163.727920]  ? asm_sysvec_apic_timer_interrupt+0x16/0x20
> [627163.727927]  ? xas_descend+0x1b/0x70
> [627163.727930]  xas_load+0x2c/0x40
> [627163.727933]  xas_find+0x161/0x1a0
> [627163.727937]  find_get_entries+0x77/0x1d0
> [627163.727944]  truncate_inode_pages_range+0x244/0x3f0
> [627163.727950]  truncate_pagecache+0x44/0x60
> [627163.727955]  xfs_setattr_size+0x168/0x490 [xfs]
> [627163.728074]  xfs_vn_setattr+0x78/0x140 [xfs]
> [627163.728153]  notify_change+0x34f/0x4f0
> [627163.728158]  ? _raw_spin_lock+0x13/0x30
> [627163.728165]  ? do_truncate+0x80/0xd0
> [627163.728169]  do_truncate+0x80/0xd0
> [627163.728172]  do_open+0x2ce/0x400
> [627163.728177]  path_openat+0x10d/0x280
> [627163.728181]  do_filp_open+0xb2/0x150
> [627163.728186]  ? check_heap_object+0x34/0x190
> [627163.728189]  ? __check_object_size.part.0+0x5a/0x130
> [627163.728194]  do_sys_openat2+0x92/0xc0
> [627163.728197]  __x64_sys_openat+0x53/0x90
> [627163.728200]  do_syscall_64+0x35/0x80
> [627163.728206]  entry_SYSCALL_64_after_hwframe+0x4b/0xb5
> [627163.728210] RIP: 0033:0x7fc5e493e7fb
> [627163.728213] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18
> 00 00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f
> 05 <48> 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 54 24 28 64 48 2b 14 25
> [627163.728215] RSP: 002b:00007ffdd4e300e0 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000101
> [627163.728218] RAX: ffffffffffffffda RBX: 00007ffdd4e30180 RCX:
> 00007fc5e493e7fb
> [627163.728220] RDX: 0000000000000241 RSI: 00007ffdd4e30180 RDI:
> 00000000ffffff9c
> [627163.728221] RBP: 00007ffdd4e30180 R08: 00007fc5e4600040 R09:
> 0000000000000001
> [627163.728223] R10: 00000000000001b6 R11: 0000000000000246 R12:
> 0000000000000241
> [627163.728224] R13: 0000000000000000 R14: 00007fc5e4662fa8 R15:
> 0000000000000000
> [627163.728227]  </TASK>
>
> I have around 50 hosts handling high I/O (each with 20Gbps+ uplinks
> and multiple NVMe drives), running RockyLinux 8/9. The stock RHEL
> kernel 8/9 is NOT affected, and the long-term kernel 5.15.X is NOT affected.
> However, with long-term kernels 6.1.XX and 6.6.XX,
> (tested at least 10 different versions), this lockup always appears
> after 2-30 days, similar to the report in the original thread.
> The more load (for example, copying a lot of local files while
> serving 20Gbps traffic), the higher the chance that the bug will appear.
>
> I haven't been able to reproduce this during synthetic tests,
> but it always occurs in production on 6.1.X and 6.6.X within 2-30 days.
> If anyone can provide a patch, I can test it on multiple machines
> over the next few days.
Could you please try this one which could be applied on 6.6 directly. Thank you!
>
> Regards,
> Marcin

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