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From: Rosen Penev <rosenp@gmail.com>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>,
	Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Samuel Sieb <samuel@sieb.net>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: MT76x2U crashes XHCI driver on AMD Ryzen system
Date: Sun, 3 Mar 2019 23:20:45 -0800	[thread overview]
Message-ID: <CAKxU2N-k-9DCYBv6W3CohL963dr3AeY3VHyt8FrUuo=BfacDsw@mail.gmail.com> (raw)
In-Reply-To: <20190304071037.GA2787@redhat.com>

On Sun, Mar 3, 2019 at 11:10 PM Stanislaw Gruszka <sgruszka@redhat.com> wrote:
>
> On Thu, Feb 28, 2019 at 02:40:29PM +0100, Joerg Roedel wrote:
> > On Thu, Feb 28, 2019 at 01:19:48PM +0100, Stanislaw Gruszka wrote:
> > > Nevermind, the patch is wrong, s->dma_address is initalized in sg_num_pages().
> >
> > Yes, it is. In sg_num_pages() the offset into the IOMMU mapping is
> > stored in s->dma_address, taking also the segment boundary mask into
> > account. map_sg() later only adds the base-address to that.
>
> I have some more info about the issues in
> https://bugzilla.kernel.org/show_bug.cgi?id=202673
>
> We have some bugs in mt76. Apparently we should not use
> page_frag_alloc() with size bigger than PAGE_SIZE as page_frag_alloc()
> can fallback to single page allocation. And also we should not make
> sizes unaligned as pointed in commit:
> 3bed3cc4156e ("net: Do not allocate page fragments that are not skb aligned"
As a small and totally unrelated note, page_frag_alloc is only used in
mt76 and the nvme driver ;)
>
> However after fixing that mt76usb still did not work. To make things
> work we had to change rx frag size from 2048 to PAGE_SIZE and change
> virt_to_head_page() to virt_to_page() when setting SG's.
>
> I think I understand why first change was needed. If we do 2 separate
> dma maps of 2 different buffers in single page i.e (PAGE + off=0
> and PAGE + off=2048) it causes problem. So either map_sg() return
> error which mt76usb does not handle correctly or there is issue
> in AMD IOMMU because two dma maps use the same page.
>
> But I don't understand why the second change was needed. Without
> it we have issue with incorrect page->_refcount . It is somehow
> related with AMD IOMMU, because on different platforms we do not
> have such problems.
>
> Joerg, could you look at this ? Thanks.
>
> Stanislaw

  reply	other threads:[~2019-03-04  7:21 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10 22:55 MT76x2U crashes XHCI driver on AMD Ryzen system Rosen Penev
2019-01-11 17:29 ` Lorenzo Bianconi
2019-01-11 19:01   ` Rosen Penev
2019-01-13 13:33     ` Lorenzo Bianconi
     [not found]       ` <1547404075.1582.0@smtp.gmail.com>
2019-01-13 19:00         ` Lorenzo Bianconi
2019-01-14  2:20           ` Rosen Penev
2019-01-14  3:13             ` Samuel Sieb
2019-01-14  9:18             ` Lorenzo Bianconi
2019-01-14  9:22               ` Tom Psyborg
2019-01-14 20:06               ` Rosen Penev
2019-01-15  9:04                 ` Lorenzo Bianconi
2019-02-18 14:37                   ` Stanislaw Gruszka
2019-02-18 14:37                     ` Stanislaw Gruszka
2019-02-18 15:15                     ` Lorenzo Bianconi
2019-02-18 15:15                       ` Lorenzo Bianconi
2019-02-18 17:01                     ` Robin Murphy
2019-02-19 11:08                       ` Stanislaw Gruszka
2019-02-19 11:08                         ` Stanislaw Gruszka
2019-02-26 10:05                     ` Joerg Roedel
2019-02-26 10:05                       ` Joerg Roedel
2019-02-26 10:34                       ` Stanislaw Gruszka
2019-02-26 10:44                         ` Joerg Roedel
2019-02-26 11:24                           ` Stanislaw Gruszka
2019-02-28  9:04                             ` Stanislaw Gruszka
2019-02-28 10:42                               ` Stanislaw Gruszka
2019-02-28 12:19                                 ` Stanislaw Gruszka
2019-02-28 13:40                                   ` Joerg Roedel
2019-03-04  7:10                                     ` Stanislaw Gruszka
2019-03-04  7:20                                       ` Rosen Penev [this message]
2019-03-11  8:43                                         ` Stanislaw Gruszka
2019-03-11  8:43                                           ` Stanislaw Gruszka
2019-03-11  8:43                                           ` Stanislaw Gruszka
2019-03-11  9:03                                           ` [PATCH] iommu/amd: fix sg->dma_address for sg->offset bigger than PAGE_SIZE Stanislaw Gruszka
2019-03-11  9:03                                             ` Stanislaw Gruszka
2019-03-11  9:03                                             ` Stanislaw Gruszka
2019-03-11 15:47                                             ` Alexander Duyck
2019-03-11 15:47                                               ` Alexander Duyck
2019-03-11 15:47                                               ` Alexander Duyck
2019-03-12  7:08                                               ` Stanislaw Gruszka
2019-03-12  7:08                                                 ` Stanislaw Gruszka
2019-03-12 15:18                                                 ` Alexander Duyck
2019-03-12 15:18                                                   ` Alexander Duyck
2019-03-12 15:18                                                   ` Alexander Duyck
2019-03-13  9:03                                                   ` [PATCH v2] " Stanislaw Gruszka
2019-03-13  9:03                                                     ` Stanislaw Gruszka
2019-03-13  9:03                                                     ` Stanislaw Gruszka
2019-03-18 10:17                                                     ` Joerg Roedel
2019-03-18 10:17                                                       ` Joerg Roedel
     [not found]                                                     ` <20190325003822.2AB72213F2@mail.kernel.org>
2019-03-25 11:19                                                       ` Stanislaw Gruszka
2019-03-12  7:13                                           ` MT76x2U crashes XHCI driver on AMD Ryzen system Stanislaw Gruszka
2019-03-12  7:13                                             ` Stanislaw Gruszka
2019-03-12  7:13                                             ` Stanislaw Gruszka

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