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Date:   Mon, 18 May 2020 09:37:15 +0100
From:   Will Deacon <will@kernel.org>
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     linux-kernel@vger.kernel.org, elver@google.com, tglx@linutronix.de,
        paulmck@kernel.org, mingo@kernel.org, peterz@infradead.org,
        "David S. Miller" <davem@davemloft.net>, rppt@kernel.org
Subject: Re: [PATCH v5 04/18] sparc32: mm: Reduce allocation size for PMD and
 PTE tables
Message-ID: <20200518083715.GA31383@willie-the-truck>
References: <20200511204150.27858-1-will@kernel.org>
 <20200511204150.27858-5-will@kernel.org>
 <20200517000050.GA87467@roeck-us.net>
 <20200517000750.GA157503@roeck-us.net>
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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@davemloft.net>
> > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > Signed-off-by: Will Deacon <will@kernel.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

If you're seeing this on powerpc too, I wonder if it's related to:

https://lore.kernel.org/r/20200514170327.31389-1-rppt@kernel.org

since I think it just hit -next and the diffstat is all over the place. I've
added Mike to CC just in case.

Will