linux-kernel - Re: [PATCH v5 04/18] sparc32: mm: Reduce allocation size for PMD and PTE tables

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Date:   Mon, 18 May 2020 11:21:28 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Mike Rapoport <rppt@...nel.org>, Will Deacon <will@...nel.org>,
        linux-kernel@...r.kernel.org, elver@...gle.com, tglx@...utronix.de,
        paulmck@...nel.org, mingo@...nel.org, peterz@...radead.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v5 04/18] sparc32: mm: Reduce allocation size for PMD and
 PTE tables

On Mon, May 18, 2020 at 11:09:46AM -0700, Guenter Roeck wrote:
> On 5/18/20 7:23 AM, Mike Rapoport wrote:
> > On Mon, May 18, 2020 at 02:48:18AM -0700, Guenter Roeck wrote:
> >> On 5/18/20 1:37 AM, Will Deacon wrote:
> >>> On Sat, May 16, 2020 at 05:07:50PM -0700, Guenter Roeck wrote:
> >>>> On Sat, May 16, 2020 at 05:00:50PM -0700, Guenter Roeck wrote:
> >>>>> On Mon, May 11, 2020 at 09:41:36PM +0100, Will Deacon wrote:
> >>>>>> Now that the page table allocator can free page table allocations
> >>>>>> smaller than PAGE_SIZE, reduce the size of the PMD and PTE allocations
> >>>>>> to avoid needlessly wasting memory.
> >>>>>>
> >>>>>> Cc: "David S. Miller" <davem@...emloft.net>
> >>>>>> Cc: Peter Zijlstra <peterz@...radead.org>
> >>>>>> Signed-off-by: Will Deacon <will@...nel.org>
> >>>>>
> >>>>> Something in the sparc32 patches in linux-next causes all my sparc32 emulations
> >>>>> to crash. bisect points to this patch, but reverting it doesn't help, and neither
> >>>>> does reverting the rest of the series.
> >>>>>
> >>>> Actually, turns out I see the same pattern (lots of scheduling while atomic
> >>>> followed by 'killing interrupt handler' in cryptomgr_test) with several
> >>>> powerpc boot tests.  I am currently bisecting those crashes. I'll report
> >>>> the results here as well as soon as I have it.
> >>>
> >>> FWIW, I retested my sparc32 patches with PREEMPT=y and I don't see any
> >>> issues. However, linux-next is a different story, where I don't get very far
> >>> at all:
> >>>
> >>> BUG: Bad page state in process swapper  pfn:005b4
> > 
> > This one seems to be due to commit 24aab577764f ("mm: memmap_init:
> > iterate over memblock regions rather that check each PFN") and reverting
> > it and partially reverting the next cleanup commits makes those
> > dissapear. sparc32 boot still fails on today's linux-next and mmotm for me with
> > 
> > Run /sbin/init as init process
> >   with arguments:
> >     /sbin/init
> >   with environment:
> >     HOME=/
> >     TERM=linux
> > Starting init: /sbin/init exists but couldn't execute it (error -14)
> > 
> > I've tried to bisect mmotm and I've got the first bad commits in
> > different places in the middle of arch/kmap series [1] so I've added Ira
> > to CC as well :)
> > 
> > I'll continue to look into "bad page" on sparc32

mips is broken too.

Does anyone know what this FIXME was for?

...
        if (vaddr < FIXADDR_START) { // FIXME
...

I'm going to remove it...

Ira