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From:   patrick wang <patrick.wang.shcn@gmail.com>
Date:   Wed, 13 Apr 2022 18:28:47 +0800
Message-ID: <CAGcnep9BW9+wam0Lu2njqpX_3fZPrEvsbs5hg66X0hTNqG3JwQ@mail.gmail.com>
Subject: Re: [PATCH] of: fdt: do not reserve memory below MIN_MEMBLOCK_ADDR
To:     Rob Herring <robh+dt@kernel.org>
Cc:     Mike Rapoport <rppt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        devicetree@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Wed, Apr 13, 2022 at 12:06 AM patrick wang
<patrick.wang.shcn@gmail.com> wrote:
>
> I check the code again, it's not about  reserved memory, it's the calling=
 of
> kmemleak_alloc_phys, this api is for lowmem, added in commit 9099daed9c6.
>
> So I think the address should be checked before kmemleak_alloc_phys,
> only the range in lowmem should be passed to the  kmemleak api.
>
> if (size &&
>     early_init_dt_reserve_memory_arch(base, size, nomap) =3D=3D 0) {
> pr_debug("Reserved memory: reserved region for node '%s': base %pa,
> size %lu MiB\n",
> uname, &base, (unsigned long)(size / SZ_1M));
> if (!nomap)
> kmemleak_alloc_phys(base, size, 0, 0); // here to check
> }
>

Since the kmemleak_alloc_phys api is only for lowmem, this should be
handled by itself.

I will post a patch to kmemleak.

>
>
> Rob Herring <robh+dt@kernel.org> =E4=BA=8E2022=E5=B9=B44=E6=9C=8812=E6=97=
=A5=E5=91=A8=E4=BA=8C 20:31=E5=86=99=E9=81=93=EF=BC=9A
> >
> > +Mike Rapoport
> >
> > On Mon, Apr 11, 2022 at 11:52 PM Patrick Wang
> > <patrick.wang.shcn@gmail.com> wrote:
> > >
> > > Dt reserve memory without base checking, which will trigger an oops i=
n
> > > kmemleak when the base address is below MIN_MEMBLOCK_ADDR:
> >
> > Why does the caller need to know what this address is? Shouldn't
> > memblock handle all this internally?

early_init_dt_add_memory_arch() handled this.


> >
> > What about when EFI memory maps are used?

If reserved memory should be handled, this should also be handled too, I th=
ink.

Thanks

> >
> > >
> > > # echo scan > /sys/kernel/debug/kmemleak
> > > [   54.888353] Unable to handle kernel paging request at virtual addr=
ess ff5fffffffe00000
> > > [   54.888932] Oops [#1]
> > > [   54.889102] Modules linked in:
> > > [   54.889326] CPU: 2 PID: 134 Comm: bash Not tainted 5.18.0-rc1-next=
-20220407 #33
> > > [   54.889620] Hardware name: riscv-virtio,qemu (DT)
> > > [   54.889901] epc : scan_block+0x74/0x15c
> > > [   54.890215]  ra : scan_block+0x72/0x15c
> > > [   54.890390] epc : ffffffff801e5806 ra : ffffffff801e5804 sp : ff20=
0000104abc30
> > > [   54.890607]  gp : ffffffff815cd4e8 tp : ff60000004cfa340 t0 : 0000=
000000000200
> > > [   54.890835]  t1 : 00aaaaaac23954cc t2 : 00000000000003ff s0 : ff20=
0000104abc90
> > > [   54.891024]  s1 : ffffffff81b0ff28 a0 : 0000000000000000 a1 : ff5f=
ffffffe01000
> > > [   54.891201]  a2 : ffffffff81b0ff28 a3 : 0000000000000002 a4 : 0000=
000000000001
> > > [   54.891377]  a5 : 0000000000000000 a6 : ff200000104abd7c a7 : 0000=
000000000005
> > > [   54.891552]  s2 : ff5fffffffe00ff9 s3 : ffffffff815cd998 s4 : ffff=
ffff815d0e90
> > > [   54.891727]  s5 : ffffffff81b0ff28 s6 : 0000000000000020 s7 : ffff=
ffff815d0eb0
> > > [   54.891903]  s8 : ffffffffffffffff s9 : ff5fffffffe00000 s10: ff5f=
ffffffe01000
> > > [   54.892078]  s11: 0000000000000022 t3 : 00ffffffaa17db4c t4 : 0000=
00000000000f
> > > [   54.892271]  t5 : 0000000000000001 t6 : 0000000000000000
> > > [   54.892408] status: 0000000000000100 badaddr: ff5fffffffe00000 cau=
se: 000000000000000d
> > > [   54.892643] [<ffffffff801e5a1c>] scan_gray_list+0x12e/0x1a6
> > > [   54.892824] [<ffffffff801e5d3e>] kmemleak_scan+0x2aa/0x57e
> > > [   54.892961] [<ffffffff801e633c>] kmemleak_write+0x32a/0x40c
> > > [   54.893096] [<ffffffff803915ac>] full_proxy_write+0x56/0x82
> > > [   54.893235] [<ffffffff801ef456>] vfs_write+0xa6/0x2a6
> > > [   54.893362] [<ffffffff801ef880>] ksys_write+0x6c/0xe2
> > > [   54.893487] [<ffffffff801ef918>] sys_write+0x22/0x2a
> > > [   54.893609] [<ffffffff8000397c>] ret_from_syscall+0x0/0x2
> > > [   54.894183] ---[ end trace 0000000000000000 ]---
> > >
> > > Add base checking and ignore the range lower than MIN_MEMBLOCK_ADDR.
> > >
> > > Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com>
> > > ---
> > >  drivers/of/fdt.c | 27 ++++++++++++++++++++-------
> > >  1 file changed, 20 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> > > index ec315b060..296c4ab8e 100644
> > > --- a/drivers/of/fdt.c
> > > +++ b/drivers/of/fdt.c
> > > @@ -33,6 +33,13 @@
> > >
> > >  #include "of_private.h"
> > >
> > > +#ifndef MIN_MEMBLOCK_ADDR
> > > +#define MIN_MEMBLOCK_ADDR      __pa(PAGE_OFFSET)
> > > +#endif
> > > +#ifndef MAX_MEMBLOCK_ADDR
> > > +#define MAX_MEMBLOCK_ADDR      ((phys_addr_t)~0)
> > > +#endif
> > > +
> > >  /*
> > >   * of_fdt_limit_memory - limit the number of regions in the /memory =
node
> > >   * @limit: maximum entries
> > > @@ -480,6 +487,19 @@ static u32 of_fdt_crc32;
> > >  static int __init early_init_dt_reserve_memory_arch(phys_addr_t base=
,
> > >                                         phys_addr_t size, bool nomap)
> > >  {
> > > +       const u64 phys_offset =3D MIN_MEMBLOCK_ADDR;
> > > +
> > > +       if (base < phys_offset) {
> > > +               pr_warn("Ignoring reserved memory range 0x%llx - 0x%l=
lx\n",
> > > +                       base, phys_offset);
> > > +               size =3D (phys_offset - base) < size ?
> > > +                       size - (phys_offset - base) : 0;
> > > +               base =3D phys_offset;
> > > +
> > > +               if (!size)
> > > +                       return -EFAULT;
> > > +       }
> > > +
> > >         if (nomap) {
> > >                 /*
> > >                  * If the memory is already reserved (by another regi=
on), we
> > > @@ -1198,13 +1218,6 @@ int __init early_init_dt_scan_chosen(char *cmd=
line)
> > >         return 0;
> > >  }
> > >
> > > -#ifndef MIN_MEMBLOCK_ADDR
> > > -#define MIN_MEMBLOCK_ADDR      __pa(PAGE_OFFSET)
> > > -#endif
> > > -#ifndef MAX_MEMBLOCK_ADDR
> > > -#define MAX_MEMBLOCK_ADDR      ((phys_addr_t)~0)
> > > -#endif
> > > -
> > >  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
> > >  {
> > >         const u64 phys_offset =3D MIN_MEMBLOCK_ADDR;
> > > --
> > > 2.25.1
> > >