[Intel-gfx] Regression in linux-next
Borah, Chaitanya Kumar
chaitanya.kumar.borah at intel.com
Wed Jul 26 03:55:13 UTC 2023
Hello Tvrtko,
Your analysis is correct. Alistair has sent a new patch set with a fix.
Thank you.
Regards
Chaitanya
> -----Original Message-----
> From: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Sent: Tuesday, July 25, 2023 4:24 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>;
> apopple at nvidia.com
> Cc: Nikula, Jani <jani.nikula at intel.com>; intel-gfx at lists.freedesktop.org; linux-
> kernel at vger.kernel.org; linux-mm at kvack.org; Kurmi, Suresh Kumar
> <suresh.kumar.kurmi at intel.com>; Yedireswarapu, SaiX Nandan
> <saix.nandan.yedireswarapu at intel.com>
> Subject: Re: [Intel-gfx] Regression in linux-next
>
>
> On 25/07/2023 07:42, Borah, Chaitanya Kumar wrote:
> > Hello Alistair,
> >
> > Hope you are doing well. I am Chaitanya from the linux graphics team in
> Intel.
> >
> > This mail is regarding a regression we are seeing in our CI runs[1] on
> > linux-next repository.
> >
> > On next-20230720 [2], we are seeing the following error
> >
> > <4>[ 76.189375] Hardware name: Intel Corporation Meteor Lake Client
> Platform/MTL-P DDR5 SODIMM SBS RVP, BIOS
> MTLPFWI1.R00.3271.D81.2307101805 07/10/2023
> > <4>[ 76.202534] RIP: 0010:__mmu_notifier_register+0x40/0x210
> > <4>[ 76.207804] Code: 1a 71 5a 01 85 c0 0f 85 ec 00 00 00 48 8b 85 30 01 00
> 00 48 85 c0 0f 84 04 01 00 00 8b 85 cc 00 00 00 85 c0 0f 8e bb 01 00 00 <49> 8b
> 44 24 10 48 83 78 38 00 74 1a 48 83 78 28 00 74 0c 0f 0b b8
> > <4>[ 76.226368] RSP: 0018:ffffc900019d7ca8 EFLAGS: 00010202
> > <4>[ 76.231549] RAX: 0000000000000001 RBX: 0000000000001000 RCX:
> 0000000000000001
> > <4>[ 76.238613] RDX: 0000000000000000 RSI: ffffffff823ceb7b RDI:
> ffffffff823ee12d
> > <4>[ 76.245680] RBP: ffff888102ec9b40 R08: 00000000ffffffff R09:
> 0000000000000001
> > <4>[ 76.252747] R10: 0000000000000001 R11: ffff8881157cd2c0 R12:
> 0000000000000000
> > <4>[ 76.259811] R13: ffff888102ec9c70 R14: ffffffffa07de500 R15:
> ffff888102ec9ce0
> > <4>[ 76.266875] FS: 00007fbcabe11c00(0000) GS:ffff88846ec00000(0000)
> knlGS:0000000000000000
> > <4>[ 76.274884] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > <4>[ 76.280578] CR2: 0000000000000010 CR3: 000000010d4c2005 CR4:
> 0000000000f70ee0
> > <4>[ 76.287643] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> > <4>[ 76.294711] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7:
> 0000000000000400
> > <4>[ 76.301775] PKRU: 55555554
> > <4>[ 76.304463] Call Trace:
> > <4>[ 76.306893] <TASK>
> > <4>[ 76.308983] ? __die_body+0x1a/0x60
> > <4>[ 76.312444] ? page_fault_oops+0x156/0x450
> > <4>[ 76.316510] ? do_user_addr_fault+0x65/0x980
> > <4>[ 76.320747] ? exc_page_fault+0x68/0x1a0
> > <4>[ 76.324643] ? asm_exc_page_fault+0x26/0x30
> > <4>[ 76.328796] ? __mmu_notifier_register+0x40/0x210
> > <4>[ 76.333460] ? __mmu_notifier_register+0x11c/0x210
> > <4>[ 76.338206] ? preempt_count_add+0x4c/0xa0
> > <4>[ 76.342273] mmu_notifier_register+0x30/0xe0
> > <4>[ 76.346509] mmu_interval_notifier_insert+0x74/0xb0
> > <4>[ 76.351344] i915_gem_userptr_ioctl+0x21a/0x320 [i915]
> > <4>[ 76.356565] ? __pfx_i915_gem_userptr_ioctl+0x10/0x10 [i915]
> > <4>[ 76.362271] drm_ioctl_kernel+0xb4/0x150
> > <4>[ 76.366159] drm_ioctl+0x21d/0x420
> > <4>[ 76.369537] ? __pfx_i915_gem_userptr_ioctl+0x10/0x10 [i915]
> > <4>[ 76.375242] ? find_held_lock+0x2b/0x80
> > <4>[ 76.379046] __x64_sys_ioctl+0x79/0xb0
> > <4>[ 76.382766] do_syscall_64+0x3c/0x90
> > <4>[ 76.386312] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> > <4>[ 76.391317] RIP: 0033:0x7fbcae63f3ab
> >
> > Details log can be found in [3].
> >
> > After bisecting the tree, the following patch seems to be causing the
> > regression.
> >
> > commit 828fe4085cae77acb3abf7dd3d25b3ed6c560edf
> > Author: Alistair Popple apopple at nvidia.com
> > Date: Wed Jul 19 22:18:46 2023 +1000
> >
> > mmu_notifiers: rename invalidate_range notifier
> >
> > There are two main use cases for mmu notifiers. One is by KVM which
> uses
> > mmu_notifier_invalidate_range_start()/end() to manage a software TLB.
> >
> > The other is to manage hardware TLBs which need to use the
> > invalidate_range() callback because HW can establish new TLB entries at
> > any time. Hence using start/end() can lead to memory corruption as
> these
> > callbacks happen too soon/late during page unmap.
> >
> > mmu notifier users should therefore either use the start()/end() callbacks
> > or the invalidate_range() callbacks. To make this usage clearer rename
> > the invalidate_range() callback to arch_invalidate_secondary_tlbs() and
> > update documention.
> >
> > Link:
> >
> https://lkml.kernel.org/r/9a02dde2f8ddaad2db31e54706a80c12d1817aaf.168
> > 9768831.git-series.apopple at nvidia.com
> >
> >
> > We also verified by reverting the patch in the tree.
> >
> > Could you please check why this patch causes the regression and if we
> > can find a solution for it soon?
>
> Without checking out the whole tree but only looking at this patch in
> isolation, it could be that it is not considering NULL subscription can be
> passed to mmu_notifier_register. For instance from
> mmu_interval_notifier_insert, which i915 is calling. So the check patch added
> to __mmu_notifier_register causes a null pointer dereference:
>
> @@ -616,6 +617,15 @@ int __mmu_notifier_register(struct mmu_notifier
> *subscription,
> mmap_assert_write_locked(mm);
> BUG_ON(atomic_read(&mm->mm_users) <= 0);
>
> + /*
> + * Subsystems should only register for invalidate_secondary_tlbs() or
> + * invalidate_range_start()/end() callbacks, not both.
> + */
> + if
> + (WARN_ON_ONCE(subscription->ops->arch_invalidate_secondary_tlbs &&
>
> ---> subscription is NULL here <---
>
> + (subscription->ops->invalidate_range_start ||
> + subscription->ops->invalidate_range_end)))
> + return -EINVAL;
> +
>
> Regards,
>
> Tvrtko
>
> >
> > [1] https://intel-gfx-ci.01.org/tree/linux-next/combined-alt.html?
> > [2]
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/co
> > mmit/?h=next-20230720 [3]
> > https://intel-gfx-ci.01.org/tree/linux-next/next-20230720/bat-mtlp-6/d
> > mesg0.txt
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