Re: [PATCH] Revert "xen: add helpers to allocate unpopulated memory"

[Jürgen Groß <jgross@xxxxxxxx>]

On 06.12.20 18:22, Marek Marczykowski-Górecki wrote:
> This reverts commit 9e2369c06c8a181478039258a4598c1ddd2cadfa.
>
> On a Xen PV dom0, with NVME disk, this makes the dom0 crash when starting
> a domain. This looks like some bad interaction between xen-blkback and
xen-scsiback has the same use pattern.

> NVME driver, both using ZONE_DEVICE. Since the author is on leave now,
> revert the change until proper solution is developed.
>
> The specific crash message is:
>
>      general protection fault, probably for non-canonical address 
> 0xdead000000000100: 0000 [#1] SMP NOPTI
>      CPU: 1 PID: 134 Comm: kworker/u12:2 Not tainted 5.9.9-1.qubes.x86_64 #1
>      Hardware name: LENOVO 20M9CTO1WW/20M9CTO1WW, BIOS N2CET50W (1.33 ) 
> 01/15/2020
>      Workqueue: dm-thin do_worker [dm_thin_pool]
>      RIP: e030:nvme_map_data+0x300/0x3a0 [nvme]
>      Code: b8 fe ff ff e9 a8 fe ff ff 4c 8b 56 68 8b 5e 70 8b 76 74 49 8b 02 48 c1 e8 
> 33 83 e0 07 83 f8 04 0f 85 f2 fe ff ff 49 8b 42 08 <83> b8 d0 00 00 00 04 0f 85 
> e1 fe ff ff e9 38 fd ff ff 8b 55 70 be
>      RSP: e02b:ffffc900010e7ad8 EFLAGS: 00010246
>      RAX: dead000000000100 RBX: 0000000000001000 RCX: ffff8881a58f5000
>      RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff8881a679e000
>      RBP: ffff8881a5ef4c80 R08: ffff8881a5ef4c80 R09: 0000000000000002
>      R10: ffffea0003dfff40 R11: 0000000000000008 R12: ffff8881a679e000
>      R13: ffffc900010e7b20 R14: ffff8881a70b5980 R15: ffff8881a679e000
>      FS:  0000000000000000(0000) GS:ffff8881b5440000(0000) 
> knlGS:0000000000000000
>      CS:  e030 DS: 0000 ES: 0000 CR0: 0000000080050033
>      CR2: 0000000001d64408 CR3: 00000001aa2c0000 CR4: 0000000000050660
>      Call Trace:
>       nvme_queue_rq+0xa7/0x1a0 [nvme]
>       __blk_mq_try_issue_directly+0x11d/0x1e0
>       ? add_wait_queue_exclusive+0x70/0x70
>       blk_mq_try_issue_directly+0x35/0xc0l[
>       blk_mq_submit_bio+0x58f/0x660
>       __submit_bio_noacct+0x300/0x330
>       process_shared_bio+0x126/0x1b0 [dm_thin_pool]
>       process_cell+0x226/0x280 [dm_thin_pool]
>       process_thin_deferred_cells+0x185/0x320 [dm_thin_pool]
>       process_deferred_bios+0xa4/0x2a0 [dm_thin_pool]UX
>       do_worker+0xcc/0x130 [dm_thin_pool]
>       process_one_work+0x1b4/0x370
>       worker_thread+0x4c/0x310
>       ? process_one_work+0x370/0x370
>       kthread+0x11b/0x140
>       ? __kthread_bind_mask+0x60/0x60<
>       ret_from_fork+0x22/0x30
>      Modules linked in: loop snd_seq_dummy snd_hrtimer nf_tables nfnetlink vfat 
> fat snd_sof_pci snd_sof_intel_byt snd_sof_intel_ipc snd_sof_intel_hda_common 
> snd_soc_hdac_hda snd_sof_xtensa_dsp snd_sof_intel_hda snd_sof snd_soc_skl 
> snd_soc_sst_
>      ipc snd_soc_sst_dsp snd_hda_ext_core snd_soc_acpi_intel_match snd_soc_acpi 
> snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine elan_i2c 
> snd_hda_codec_hdmi mei_hdcp iTCO_wdt intel_powerclamp intel_pmc_bxt ee1004 
> intel_rapl_msr iTCO_vendor
>      _support joydev pcspkr intel_wmi_thunderbolt wmi_bmof thunderbolt 
> ucsi_acpi idma64 typec_ucsi snd_hda_codec_realtek typec snd_hda_codec_generic 
> snd_hda_intel snd_intel_dspcfg snd_hda_codec thinkpad_acpi snd_hda_core 
> ledtrig_audio int3403_
>      thermal snd_hwdep snd_seq snd_seq_device snd_pcm iwlwifi snd_timer 
> processor_thermal_device mei_me cfg80211 intel_rapl_common snd e1000e mei 
> int3400_thermal int340x_thermal_zone i2c_i801 acpi_thermal_rel soundcore 
> intel_soc_dts_iosf i2c_s
>      mbus rfkill intel_pch_thermal xenfs
>       ip_tables dm_thin_pool dm_persistent_data dm_bio_prison dm_crypt nouveau 
> rtsx_pci_sdmmc mmc_core mxm_wmi crct10dif_pclmul ttm crc32_pclmul crc32c_intel 
> i915 ghash_clmulni_intel i2c_algo_bit serio_raw nvme drm_kms_helper cec 
> xhci_pci nvme
>      _core rtsx_pci xhci_pci_renesas drm xhci_hcd wmi video pinctrl_cannonlake 
> pinctrl_intel xen_privcmd xen_pciback xen_blkback xen_gntalloc xen_gntdev 
> xen_evtchn uinput
>      ---[ end trace f8d47e4aa6724df4 ]---
>      RIP: e030:nvme_map_data+0x300/0x3a0 [nvme]
>      Code: b8 fe ff ff e9 a8 fe ff ff 4c 8b 56 68 8b 5e 70 8b 76 74 49 8b 02 48 c1 e8 
> 33 83 e0 07 83 f8 04 0f 85 f2 fe ff ff 49 8b 42 08 <83> b8 d0 00 00 00 04 0f 85 
> e1 fe ff ff e9 38 fd ff ff 8b 55 70 be
>      RSP: e02b:ffffc900010e7ad8 EFLAGS: 00010246
>      RAX: dead000000000100 RBX: 0000000000001000 RCX: ffff8881a58f5000
>      RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff8881a679e000
>      RBP: ffff8881a5ef4c80 R08: ffff8881a5ef4c80 R09: 0000000000000002
>      R10: ffffea0003dfff40 R11: 0000000000000008 R12: ffff8881a679e000
>      R13: ffffc900010e7b20 R14: ffff8881a70b5980 R15: ffff8881a679e000
>      FS:  0000000000000000(0000) GS:ffff8881b5440000(0000) 
> knlGS:0000000000000000
>      CS:  e030 DS: 0000 ES: 0000 CR0: 0000000080050033
>      CR2: 0000000001d64408 CR3: 00000001aa2c0000 CR4: 0000000000050660
>      Kernel panic - not syncing: Fatal exception
>      Kernel Offset: disabled
>
> Discussion at 
> https://lore.kernel.org/xen-devel/20201205082839.ts3ju6yta46cgwjn@Air-de-Roger/T
>
> Cc: stable@xxxxxxxxxxxxxxx #v5.9+
> (for 5.9 it's easier to revert the original commit directly)
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Acked-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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