From: Chester Lin <clin@suse.com>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Juergen Gross <JGross@suse.com>, Joey Lee <JLee@suse.com>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"guillaume.gardet@arm.com" <guillaume.gardet@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
"linux@armlinux.org.uk" <linux@armlinux.org.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Chester Lin <clin@suse.com>,
"geert@linux-m68k.org" <geert@linux-m68k.org>,
"ren_guo@c-sky.com" <ren_guo@c-sky.com>, Gary Lin <GLin@suse.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] efi/arm: fix allocation failure when reserving the kernel base
Date: Tue, 20 Aug 2019 10:29:53 +0000 [thread overview]
Message-ID: <20190820102928.GA14667@linux-8mug> (raw)
In-Reply-To: <20190820074930.GC5989@rapoport-lnx>
On Tue, Aug 20, 2019 at 10:49:30AM +0300, Mike Rapoport wrote:
> On Mon, Aug 19, 2019 at 05:56:51PM +0300, Ard Biesheuvel wrote:
> > On Mon, 19 Aug 2019 at 11:01, Chester Lin <clin@suse.com> wrote:
> > >
> > > Hi Mike and Ard,
> > >
> > > On Thu, Aug 15, 2019 at 04:37:39PM +0300, Mike Rapoport wrote:
> > > > On Thu, Aug 15, 2019 at 02:32:50PM +0300, Ard Biesheuvel wrote:
> > > > > (adding Mike)
> > > > >
>
> ...
>
> > > > > > In this case the kernel failed to reserve cma, which should hit the issue of
> > > > > > memblock_limit=0x1000 as I had mentioned in my patch description. The first
> > > > > > block [0-0xfff] was scanned in adjust_lowmem_bounds(), but it did not align
> > > > > > with PMD_SIZE so the cma reservation failed because the memblock.current_limit
> > > > > > was extremely low. That's why I expand the first reservation from 1 PAGESIZE to
> > > > > > 1 PMD_SIZE in my patch in order to avoid this issue. Please kindly let me know
> > > > > > if any suggestion, thank you.
> > > >
> > > >
> > > > > This looks like it is a separate issue. The memblock/cma code should
> > > > > not choke on a reserved page of memory at 0x0.
> > > > >
> > > > > Perhaps Russell or Mike (cc'ed) have an idea how to address this?
> > > >
> > > > Presuming that the last memblock dump comes from the end of
> > > > arm_memblock_init() with the this memory map
> > > >
> > > > memory[0x0] [0x0000000000000000-0x0000000000000fff], 0x0000000000001000 bytes flags: 0x4
> > > > memory[0x1] [0x0000000000001000-0x0000000007ef5fff], 0x0000000007ef5000 bytes flags: 0x0
> > > > memory[0x2] [0x0000000007ef6000-0x0000000007f09fff], 0x0000000000014000 bytes flags: 0x4
> > > > memory[0x3] [0x0000000007f0a000-0x000000003cb3efff], 0x0000000034c35000 bytes flags: 0x0
> > > >
> > > > adjust_lowmem_bounds() will set the memblock_limit (and respectively global
> > > > memblock.current_limit) to 0x1000 and any further memblock_alloc*() will
> > > > happily fail.
> > > >
> > > > I believe that the assumption for memblock_limit calculations was that the
> > > > first bank has several megs at least.
> > > >
> > > > I wonder if this hack would help:
> > > >
> > > > diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> > > > index d9a0038..948e5b9 100644
> > > > --- a/arch/arm/mm/mmu.c
> > > > +++ b/arch/arm/mm/mmu.c
> > > > @@ -1206,7 +1206,7 @@ void __init adjust_lowmem_bounds(void)
> > > > * allocated when mapping the start of bank 0, which
> > > > * occurs before any free memory is mapped.
> > > > */
> > > > - if (!memblock_limit) {
> > > > + if (memblock_limit < PMD_SIZE) {
> > > > if (!IS_ALIGNED(block_start, PMD_SIZE))
> > > > memblock_limit = block_start;
> > > > else if (!IS_ALIGNED(block_end, PMD_SIZE))
> > > >
> > >
> > > I applied this patch as well and it works well on rpi-2 model B.
> > >
> >
> > Thanks, Chester, that is good to know.
> >
> > However, afaict, this only affects systems where physical memory
> > starts at address 0x0, so I think we need a better fix.
>
> This hack can be easily extended to handle systems with arbitrary start
> address, but it's still a hack...
>
> > I know Mike has been looking into the NOMAP stuff lately, and your
> > original patch contains a hunk that makes this code (?) disregard
> > nomap memblocks. That might be a better approach.
>
> I was actually looking how to replace NOMAP with something else to make
> memblock.memory consistent with actual physical memory banks. But this work
> is stashed for now.
>
> I'm not sure that skipping NOMAP regions would be good enough.
> If I understand corrrectly, with Chester's original patch the reservation
> of PMD aligned chunk of 32M for the kernel made the first conv-mem region
> PMD aligned and then memblock_limit will be set to the end of this region.
>
> Is there a reason for marking EFI_RESERVED_TYPE as NOMAP rather than simply
> reserve them with memblock_reserve()?
>
Hi Mike,
I make this change in efistub so I am not sure if memblock_reserve() can be
linked by ld or not. I tried using efi_mem_reserve() but got a linker error of
undefined reference. Is there a better place to call memblock_reserve() after
efistub?
Thanks,
Chester
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-08-20 10:35 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 5:38 [PATCH] efi/arm: fix allocation failure when reserving the kernel base Chester Lin
2019-08-04 7:57 ` Ard Biesheuvel
2019-08-14 7:58 ` Guillaume Gardet
2019-08-15 7:59 ` Ard Biesheuvel
2019-08-15 11:16 ` Chester Lin
2019-08-15 11:32 ` Ard Biesheuvel
2019-08-15 13:37 ` Mike Rapoport
2019-08-19 7:56 ` Chester Lin
2019-08-19 14:56 ` Ard Biesheuvel
2019-08-20 7:33 ` Chester Lin
2019-08-20 7:49 ` Mike Rapoport
2019-08-20 10:29 ` Chester Lin [this message]
2019-08-20 11:00 ` Ard Biesheuvel
2019-08-20 11:54 ` Russell King - ARM Linux admin
2019-08-20 12:27 ` Ard Biesheuvel
2019-08-20 11:56 ` Russell King - ARM Linux admin
2019-08-20 12:28 ` Ard Biesheuvel
2019-08-21 6:10 ` Chester Lin
2019-08-21 6:35 ` Ard Biesheuvel
2019-08-21 7:11 ` Mike Rapoport
2019-08-21 7:22 ` Chester Lin
2019-08-21 7:29 ` Ard Biesheuvel
2019-08-21 8:29 ` Mike Rapoport
2019-08-21 9:42 ` Ard Biesheuvel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190820102928.GA14667@linux-8mug \
--to=clin@suse.com \
--cc=GLin@suse.com \
--cc=JGross@suse.com \
--cc=JLee@suse.com \
--cc=akpm@linux-foundation.org \
--cc=ard.biesheuvel@linaro.org \
--cc=geert@linux-m68k.org \
--cc=guillaume.gardet@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-efi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=mingo@kernel.org \
--cc=ren_guo@c-sky.com \
--cc=rppt@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).