Message-ID: <CAJD7tkaPjJWr28CzGoTK3e-4e4eP2gLSojaEH3U9X9E0KgBs8g@mail.gmail.com>
Date: Fri, 13 Sep 2024 10:39:55 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Tomáš Trnka <trnka@....com>
Cc: hannes@...xchg.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	nphamcs@...il.com, pedro.falcato@...il.com, piotr.oniszczuk@...il.com, 
	regressions@...ts.linux.dev, willy@...radead.org
Subject: Re: [regression] oops on heavy compilations ("kernel BUG at
 mm/zswap.c:1005!" and "Oops: invalid opcode: 0000")

On Fri, Sep 13, 2024 at 2:03 AM Tomáš Trnka <trnka@....com> wrote:
>
> > Well, it's possible that some zswap change was not fully compatible
> > with z3fold, or surfaced a dormant bug in z3fold. Either way, my
> > recommendation is to use zsmalloc. I have been trying to deprecate
> > z3fold, and honestly you are the only person I have seen use z3fold in
> > a while -- which is probably why no one else reported such a problem.
>
> FWIW, I have repeatedly hit this exact BUG (mm/zswap.c:1005) on two of my
> machines on 6.10.x (possibly 6.9.x as well, but I don't have the logs at hand
> to confirm). In both cases, this was also using z3fold under moderate memory
> pressure. I think this fairly conclusively rules out a HW issue.
>
> Additionally, I have hit the following BUG on 6.10.8, which is potentially
> related (note __z3fold_alloc in there):
>
> list_del corruption, ffff977c17128000->next is NULL
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:52!
> Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 3 PID: 248608 Comm: kworker/u32:3 Tainted: G        W
> 6.10.8-100.fc39.x86_64 #1
> Hardware name: HP HP EliteBook 850 G6/8549, BIOS R70 Ver. 01.28.00 04/12/2024
> Workqueue: zswap12 compact_page_work
> RIP: 0010:__list_del_entry_valid_or_report+0x5d/0xc0
> Code: 48 8b 01 48 39 f8 75 5a 48 8b 72 08 48 39 f0 75 65 b8 01 00 00 00 c3 cc
> cc cc cc 48 89 fe 48 c7 c7 f0 89 ba ad e8 73 34 8f ff <0f> 0b 48 89 fe 48 c7
> c7 20 8a ba ad e8 62 34 8f ff 0f 0b 48 89 fe
> RSP: 0018:ffffac7299f5bdb0 EFLAGS: 00010246
> RAX: 0000000000000033 RBX: ffff977c0afd0b08 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffff977f2d5a18c0 RDI: ffff977f2d5a18c0
> RBP: ffff977c0afd0b00 R08: 0000000000000000 R09: 4e20736920747865
> R10: 7478656e3e2d3030 R11: 4c4c554e20736920 R12: ffff977c17128010
> R13: 000000000000000a R14: 00000000000000a0 R15: ffff977c17128000
> FS:  0000000000000000(0000) GS:ffff977f2d580000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f063638a000 CR3: 0000000179428002 CR4: 00000000003706f0
> Call Trace:
>  <TASK>
>  ? die+0x36/0x90
>  ? do_trap+0xdd/0x100
>  ? __list_del_entry_valid_or_report+0x5d/0xc0
>  ? do_error_trap+0x6a/0x90
>  ? __list_del_entry_valid_or_report+0x5d/0xc0
>  ? exc_invalid_op+0x50/0x70
>  ? __list_del_entry_valid_or_report+0x5d/0xc0
>  ? asm_exc_invalid_op+0x1a/0x20
>  ? __list_del_entry_valid_or_report+0x5d/0xc0
>  __z3fold_alloc+0x4e/0x4b0
>  do_compact_page+0x20e/0xa60
>  process_one_work+0x17b/0x390
>  worker_thread+0x265/0x380
>  ? __pfx_worker_thread+0x10/0x10
>  kthread+0xcf/0x100
>  ? __pfx_kthread+0x10/0x10
>  ret_from_fork+0x31/0x50
>  ? __pfx_kthread+0x10/0x10
>  ret_from_fork_asm+0x1a/0x30
>  </TASK>
> Modules linked in: nf_conntrack_netbios_ns nf_conntrack_broadcast lp parport
> ti_usb_3410_5052 hid_logitech_hidpp snd_usb_audio snd_usbmidi_lib snd_ump
> snd_rawmidi hid_logitech_dj r8153_ecm cdc_ether usbnet r8152 mii ib_core
> dimlib tls >
>  snd_hda_codec_realtek snd_hda_codec_generic snd_hda_scodec_component
> snd_soc_dmic snd_sof_pci_intel_cnl snd_sof_intel_hda_generic soundwire_intel
> soundwire_cadence snd_sof_intel_hda_common snd_sof_intel_hda_mlink
> snd_sof_intel_hda snd>
>  processor_thermal_device_pci_legacy intel_cstate hp_wmi
> processor_thermal_device snd_timer sparse_keymap processor_thermal_wt_hint
> intel_uncore intel_wmi_thunderbolt thunderbolt wmi_bmof cfg80211 snd
> processor_thermal_rfim i2c_i801 sp>
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__list_del_entry_valid_or_report+0x5d/0xc0
> Code: 48 8b 01 48 39 f8 75 5a 48 8b 72 08 48 39 f0 75 65 b8 01 00 00 00 c3 cc
> cc cc cc 48 89 fe 48 c7 c7 f0 89 ba ad e8 73 34 8f ff <0f> 0b 48 89 fe 48 c7
> c7 20 8a ba ad e8 62 34 8f ff 0f 0b 48 89 fe
> RSP: 0018:ffffac7299f5bdb0 EFLAGS: 00010246
> RAX: 0000000000000033 RBX: ffff977c0afd0b08 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffff977f2d5a18c0 RDI: ffff977f2d5a18c0
> RBP: ffff977c0afd0b00 R08: 0000000000000000 R09: 4e20736920747865
> R10: 7478656e3e2d3030 R11: 4c4c554e20736920 R12: ffff977c17128010
> R13: 000000000000000a R14: 00000000000000a0 R15: ffff977c17128000
> FS:  0000000000000000(0000) GS:ffff977f2d580000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f063638a000 CR3: 0000000179428002 CR4: 00000000003706f0
> note: kworker/u32:3[248608] exited with preempt_count 3
>
> > > Is there any possibility/way to avoid bisecting? (due limited time from my
> > > side)>
> > So unless you have a reason to specifically use z3fold or avoid
> > zsmalloc, please use zsmalloc. It should be better for you anyway. I
> > doubt that you (or anyone) wants to spend time debugging a z3fold
> > problem :)
>
> I could conceivably try to bisect this, but since I don't have a quick
> reproducer, it would likely take weeks to finish. I'm wondering whether it's
> worth trying or if z3fold is going out of the door anyway. I don't think it's
> hardware-related so it should be possible to test this in a VM, but that still
> takes some effort to set up.

z3fold is going out of the door anyway, I already sent a patch to deprecate it:
https://lore.kernel.org/lkml/20240904233343.933462-1-yosryahmed@google.com/

I will send a new version after the merge window, and I will include
your bug report in the list of problems in the commit log :) Thanks
for the report, please don't waste time debugging this and use
zsmalloc!

>
> Best regards,
>
> Tomáš Trnka
>
>

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