Re: DomU application crashes while mmap'ing device memory on x86_64

[Oleksandr Andrushchenko <andr2000@gmail.com>]

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Hi,

just wanted to bump this as I also have the same issue on real HW now
(x86_64)
Nov 14 10:30:18 DomU kernel: [ 1169.569936]  [<ffffffff8101d60c>]
xen_mc_flush+0x19c/0x1b0

Thank you in advnce,
Oleksandr


On Mon, Nov 14, 2016 at 6:07 PM, Oleksandr Andrushchenko <andr2000@gmail.com
> wrote:

> Hi, there!
>
> Sorry for the long read ahead, but it seems I've got stuck...
>
> I am working on a PV driver and facing an mmap issue.
> This actually happens when user-space tries to mmap
> the memory allocated by the driver:
>
> cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr,
>       GFP_KERNEL | __GFP_NOWARN);
>
> and maping:
>
> vma->vm_flags &= ~VM_PFNMAP;
> vma->vm_pgoff = 0;
>
> ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
>  cma_obj->paddr, vma->vm_end - vma->vm_start);
>
> Return of the dma_mmap_wc is 0, but I see in the DomU kernel logs:
>
> Nov 14 10:30:18 DomU kernel: [ 1169.569909] ------------[ cut here
> ]------------
> Nov 14 10:30:18 DomU kernel: [ 1169.569911] WARNING: CPU: 1 PID: 5146 at
> /home/kernel/COD/linux/arch/x86/xen/multicalls.c:129
> xen_mc_flush+0x19c/0x1b0
> Nov 14 10:30:18 DomU kernel: [ 1169.569912] Modules linked in:
> xen_drmfront(OE) drm_kms_helper(OE) drm(OE) fb_sys_fops syscopyarea
> sysfillrect sysimgblt crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
> aesni_intel aes_x86_64 lrw glue_helper ablk_helper cryptd intel_rapl_perf
> autofs4 [last unloaded: xen_drmfront]
> Nov 14 10:30:18 DomU kernel: [ 1169.569919] CPU: 1 PID: 5146 Comm:
> lt-modetest Tainted: G        W  OE   4.9.0-040900rc3-generic #201610291831
> Nov 14 10:30:18 DomU kernel: [ 1169.569920]  ffffc900406ffb10
> ffffffff81416bf2 0000000000000000 0000000000000000
> Nov 14 10:30:18 DomU kernel: [ 1169.569923]  ffffc900406ffb50
> ffffffff8108361b 00000081406ffb30 ffff88003f90b8e0
> Nov 14 10:30:18 DomU kernel: [ 1169.569925]  0000000000000001
> 0000000000000010 0000000000000000 0000000000000201
> Nov 14 10:30:18 DomU kernel: [ 1169.569928] Call Trace:
> Nov 14 10:30:18 DomU kernel: [ 1169.569930]  [<ffffffff81416bf2>]
> dump_stack+0x63/0x81
> Nov 14 10:30:18 DomU kernel: [ 1169.569932]  [<ffffffff8108361b>]
> __warn+0xcb/0xf0
> Nov 14 10:30:18 DomU kernel: [ 1169.569934]  [<ffffffff8108374d>]
> warn_slowpath_null+0x1d/0x20
> Nov 14 10:30:18 DomU kernel: [ 1169.569936]  [<ffffffff8101d60c>]
> xen_mc_flush+0x19c/0x1b0
> Nov 14 10:30:18 DomU kernel: [ 1169.569938]  [<ffffffff8101d716>]
> __xen_mc_entry+0xf6/0x150
> Nov 14 10:30:18 DomU kernel: [ 1169.569940]  [<ffffffff81020476>]
> xen_extend_mmu_update+0x56/0xd0
> Nov 14 10:30:18 DomU kernel: [ 1169.569942]  [<ffffffff81021d67>]
> xen_set_pte_at+0x177/0x2f0
> Nov 14 10:30:18 DomU kernel: [ 1169.569944]  [<ffffffff811e064b>]
> remap_pfn_range+0x30b/0x430
> Nov 14 10:30:18 DomU kernel: [ 1169.569946]  [<ffffffff815a8267>]
> dma_common_mmap+0x87/0xa0
> Nov 14 10:30:18 DomU kernel: [ 1169.569953]  [<ffffffffc00ffa8f>]
> drm_gem_cma_mmap_obj+0x8f/0xa0 [drm]
> Nov 14 10:30:18 DomU kernel: [ 1169.569960]  [<ffffffffc00ffac5>]
> drm_gem_cma_mmap+0x25/0x30 [drm]
> Nov 14 10:30:18 DomU kernel: [ 1169.569962]  [<ffffffff811e79b5>]
> mmap_region+0x3a5/0x640
> Nov 14 10:30:18 DomU kernel: [ 1169.569964]  [<ffffffff811e8096>]
> do_mmap+0x446/0x530
> Nov 14 10:30:18 DomU kernel: [ 1169.569966]  [<ffffffff813b88b5>] ?
> common_mmap+0x45/0x50
> Nov 14 10:30:18 DomU kernel: [ 1169.569968]  [<ffffffff813b8906>] ?
> apparmor_mmap_file+0x16/0x20
> Nov 14 10:30:18 DomU kernel: [ 1169.569970]  [<ffffffff81377a5d>] ?
> security_mmap_file+0xdd/0xf0
> Nov 14 10:30:18 DomU kernel: [ 1169.569972]  [<ffffffff811c8faa>]
> vm_mmap_pgoff+0xba/0xf0
> Nov 14 10:30:18 DomU kernel: [ 1169.569974]  [<ffffffff811e5c01>]
> SyS_mmap_pgoff+0x1c1/0x290
> Nov 14 10:30:18 DomU kernel: [ 1169.569976]  [<ffffffff8103313b>]
> SyS_mmap+0x1b/0x30
> Nov 14 10:30:18 DomU kernel: [ 1169.569978]  [<ffffffff8188bbbb>]
> entry_SYSCALL_64_fastpath+0x1e/0xad
> Nov 14 10:30:18 DomU kernel: [ 1169.569979] ---[ end trace
> ce1796cb265ebe08 ]---
> Nov 14 10:30:18 DomU kernel: [ 1169.569982] ------------[ cut here
> ]------------
>
>
> And output of xl dmesg says:
>
> (XEN) memory.c:226:d0v0 Could not allocate order=9 extent: id=31
> memflags=0x40 (488 of 512)
> (d31) mapping kernel into physical memory
> (d31) about to get started...
> (XEN) d31 attempted to change d31v0's CR4 flags 00000620 -> 00040660
> (XEN) d31 attempted to change d31v1's CR4 flags 00000620 -> 00040660
> (XEN) traps.c:3657: GPF (0000): ffff82d0801a1a09 -> ffff82d08024b970
> (XEN) mm.c:1893:d31v0 Bad L1 flags 90
> (XEN) mm.c:1893:d31v0 Bad L1 flags 90
> (XEN) mm.c:1893:d31v0 Bad L1 flags 90
> (XEN) mm.c:1893:d31v0 Bad L1 flags 90
>
> My setup is a little bit tricky... I am using a Xen setup running
> inside VirtualBox:
>
> 1. xl info:
> host                   : Dom0
> release                : 4.4.0-45-generic
> version                : #66-Ubuntu SMP Wed Oct 19 14:12:37 UTC 2016
> machine                : x86_64
> nr_cpus                : 2
> max_cpu_id             : 1
> nr_nodes               : 1
> cores_per_socket       : 2
> threads_per_core       : 1
> cpu_mhz                : 3408
> hw_caps                : 178bfbff:d6d82203:28100800:
> 00000121:00000000:00842000:00000000:00000100
> virt_caps              :
> total_memory           : 2047
> free_memory            : 11
> sharing_freed_memory   : 0
> sharing_used_memory    : 0
> outstanding_claims     : 0
> free_cpus              : 0
> xen_major              : 4
> xen_minor              : 8
> xen_extra              : .0-rc
> xen_version            : 4.8.0-rc
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p
> xen_scheduler          : credit
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          :
> xen_commandline        : placeholder
> cc_compiler            : gcc (Debian 6.2.0-10) 6.2.0 20161027
> cc_compile_by          : ijackson
> cc_compile_domain      : chiark.greenend.org.uk
> cc_compile_date        : Tue Nov  1 18:11:16 UTC 2016
> build_id               : 3744fa5e7a5b01a0439ba4413e41a7a1c505d5ee
> xend_config_format     : 4
>
> 2. DomU
> Linux DomU 4.9.0-040900rc3-generic #201610291831 SMP Sat Oct 29 22:32:46
> UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
>
> Could anyone please give me any hint on what needs to
> be checked and how this can be resolved?
>
> Thank you,
> Oleksandr Andrushchenko
>



-- 
Best regards,
Oleksandr Andrushchenko

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