Thread (31 messages) 31 messages, 6 authors, 2015-01-28

Re: mmotm 2015-01-22-15-04: qemu failures due to 'mm: account pmd page tables to the process'

From: Kirill A. Shutemov <hidden>
Date: 2015-01-26 12:29:44
Also in: linux-fsdevel, linux-mm, lkml

On Fri, Jan 23, 2015 at 09:52:07PM -0800, Guenter Roeck wrote:
On Fri, Jan 23, 2015 at 01:55:19PM -0800, Andrew Morton wrote:
quoted
On Fri, 23 Jan 2015 07:07:56 -0800 Guenter Roeck [off-list ref] wrote:
quoted
quoted
quoted
qemu:microblaze generates warnings to the console.

WARNING: CPU: 0 PID: 32 at mm/mmap.c:2858 exit_mmap+0x184/0x1a4()

with various call stacks. See
http://server.roeck-us.net:8010/builders/qemu-microblaze-mmotm/builds/15/steps/qemubuildcommand/logs/stdio
for details.
Could you try patch below? Completely untested.
quoted
From b584bb8d493794f67484c0b57c161d61c02599bc Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <redacted>
Date: Fri, 23 Jan 2015 13:08:26 +0200
Subject: [PATCH] microblaze: define __PAGETABLE_PMD_FOLDED

Microblaze uses custom implementation of PMD folding, but doesn't define
__PAGETABLE_PMD_FOLDED, which generic code expects to see. Let's fix it.

Defining __PAGETABLE_PMD_FOLDED will drop out unused __pmd_alloc().
It also fixes problems with recently-introduced pmd accounting.

Signed-off-by: Kirill A. Shutemov <redacted>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested working.

Tested-by: Guenter Roeck <linux@roeck-us.net>

Any idea how to fix the sh problem ?
Can you tell us more about it?  All I'm seeing is "qemu:sh fails to
shut down", which isn't very clear.
Turns out that the include file defining __PAGETABLE_PMD_FOLDED
was not always included where used, resulting in a messed up mm_struct.
What means "messed up" here? It should only affect size of mm_struct.
 
The patch below fixes the problem for the sh architecture.
No idea if the patch is correct/acceptable for other architectures.
That's pain. Some archs includes <linux/mm_types.h> from <asm/pgtable.h>.
I don't see obvious way to fix this. Urghh.

-- 
 Kirill A. Shutemov

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