linux-kernel - Re: [PATCH v10 1/2] of: reserved_mem: Restruture how the reserved memory regions are processed

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Message-ID: <CAMuHMdUjpyZEvwKpY1oQtqiqbXYcbZBh4-7pa3jacrFaCfKF=Q@mail.gmail.com>
Date: Tue, 12 Nov 2024 19:41:38 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
Cc: robh@...nel.org, aisheng.dong@....com, andy@...ck.fi.intel.com, 
	catalin.marinas@....com, devicetree@...r.kernel.org, hch@....de, 
	iommu@...ts.linux.dev, kernel@...cinc.com, klarasmodin@...il.com, 
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com, 
	quic_ninanaik@...cinc.com, robin.murphy@....com, saravanak@...gle.com, 
	will@...nel.org, Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v10 1/2] of: reserved_mem: Restruture how the reserved
 memory regions are processed

Hi Oreoluwa,

On Fri, Nov 1, 2024 at 1:45 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> On Thu, Oct 31, 2024 at 10:06 PM Oreoluwa Babatunde
> <quic_obabatun@...cinc.com> wrote:
> > On 10/29/2024 5:41 AM, Geert Uytterhoeven wrote:
> > > On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
> > > <quic_obabatun@...cinc.com> wrote:
> > >> Reserved memory regions defined in the devicetree can be broken up into
> > >> two groups:
> > >> i) Statically-placed reserved memory regions
> > >> i.e. regions defined with a static start address and size using the
> > >>      "reg" property.
> > >> ii) Dynamically-placed reserved memory regions.
> > >> i.e. regions defined by specifying an address range where they can be
> > >>      placed in memory using the "alloc_ranges" and "size" properties.

[...]

> > >> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
> > > Thanks for your patch, which is now commit 8a6e02d0c00e7b62
> > > ("of: reserved_mem: Restructure how the reserved memory regions
> > > are processed") in dt-rh/for-next.
> > >
> > > I have bisected a boot issue on RZ/Five to this commit.
> > > With "earlycon keep_bootcon" (else there is no output):
> > >
> > >     Oops - store (or AMO) access fault [#1]
> > >     CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
> > > 6.12.0-rc1-00015-g8a6e02d0c00e #201
> > >     Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
> > >     epc : __memset+0x60/0x100
> > >      ra : __dma_alloc_from_coherent+0x150/0x17a
> > >     epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
> > >      gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
> > >      t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
> > >      s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
> > >      a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
> > >      a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
> > >      s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
> > >      s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
> > >      s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
> > >      s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
> > >      t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
> > >     status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
> > >     [<ffffffff8062d2bc>] __memset+0x60/0x100
> > >     [<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
> > >     [<ffffffff80053056>] dma_direct_alloc+0x98/0x112
> > >     [<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
> > >     [<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a

> > Please can you provide reproduction steps? I tried booting up
> > risc-v arch with qemu but did not run into the issue you are
> > seeing.
>
> It indeed doesn't happen on other RISC-V platforms (tried MPFS/Icicle).
> RZ/Five is special in that it is DMA non-coherent, and the crash
> happens in dma_alloc_from_global_coherent().
> According to the logs, the DMA pool at 0x58000000 is still being created.
> I'll try to debug this further next week...

I found the issue, and have sent a fix
https://lore.kernel.org/r/f8cef6845a6141f0277e31a71fe153612daae776.1731436631.git.geert+renesas@glider.be

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds