From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Andrew Morton <akpm@linux-foundation.org>,
Guenter Roeck <linux@roeck-us.net>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, linux-next@vger.kernel.org,
sfr@canb.auug.org.au, mhocko@suse.cz,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: mmotm 2015-01-22-15-04: qemu failures due to 'mm: account pmd page tables to the process'
Date: Tue, 27 Jan 2015 18:16:57 +0200 [thread overview]
Message-ID: <20150127161657.GA7155@node.dhcp.inet.fi> (raw)
In-Reply-To: <54C6494D.80802@roeck-us.net>
On Mon, Jan 26, 2015 at 06:03:57AM -0800, Guenter Roeck wrote:
> On 01/26/2015 04:29 AM, Kirill A. Shutemov wrote:
> >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:
> >>>On Fri, 23 Jan 2015 07:07:56 -0800 Guenter Roeck <linux@roeck-us.net> wrote:
> >>>
> >>>>>>
> >>>>>>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.
> >>>>>
> >>>>>>From b584bb8d493794f67484c0b57c161d61c02599bc Mon Sep 17 00:00:00 2001
> >>>>>From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> >>>>>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 <kirill.shutemov@linux.intel.com>
> >>>>>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.
> >
> Plus the offset of all variables after the #ifndef.
Okay, I guess the problem is that different parts of the kernel see
different mm_struct depending on include ordering.
Tried to look for options, but don't see anything better than patch below.
Andrew, is it okay to you?
>From 0f113e16a058d47f3bc63a3b6ced5296afb934a6 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Tue, 27 Jan 2015 17:59:55 +0200
Subject: [PATCH] mm: add nr_pmds into mm_struct unconditionally
__PAGETABLE_PMD_FOLDED is defined during <asm/pgtable.h> which is not
included into <linux/mm_types.h>. And we cannot include it here since
many of <asm/pgtables> needs <linux/mm_types.h> to define struct page.
I failed to come up with better solution rather than put nr_pmds into
mm_struct unconditionally.
One possible solution would be to expose number of page table levels
architecture has via Kconfig, but that's ugly and requires changes to
all architectures.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/mm_types.h | 2 --
1 file changed, 2 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 79cdf6f5c746..199a03aab8dc 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -364,9 +364,7 @@ struct mm_struct {
atomic_t mm_users; /* How many users with user space? */
atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
atomic_long_t nr_ptes; /* PTE page table pages */
-#ifndef __PAGETABLE_PMD_FOLDED
atomic_long_t nr_pmds; /* PMD page table pages */
-#endif
int map_count; /* number of VMAs */
spinlock_t page_table_lock; /* Protects page tables and some counters */
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2015-01-27 16:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-22 23:05 mmotm 2015-01-22-15-04 uploaded akpm
2015-01-23 5:04 ` mmotm 2015-01-22-15-04: qemu failures due to 'mm: account pmd page tables to the process' Guenter Roeck
2015-01-23 11:13 ` Kirill A. Shutemov
2015-01-23 15:07 ` Guenter Roeck
2015-01-23 21:55 ` Andrew Morton
2015-01-24 2:44 ` Guenter Roeck
2015-01-24 3:05 ` Guenter Roeck
2015-01-24 5:52 ` Guenter Roeck
2015-01-26 12:29 ` Kirill A. Shutemov
2015-01-26 14:03 ` Guenter Roeck
2015-01-26 14:17 ` Guenter Roeck
2015-01-27 16:16 ` Kirill A. Shutemov [this message]
2015-01-27 16:24 ` Guenter Roeck
2015-01-27 21:24 ` Andrew Morton
2015-01-28 6:16 ` Guenter Roeck
2015-01-23 5:08 ` mmotm 2015-01-22-15-04: qemu failure due to 'mm: memcontrol: remove unnecessary soft limit tree node test' Guenter Roeck
2015-01-23 14:18 ` Johannes Weiner
2015-01-23 15:17 ` Christoph Lameter
2015-01-23 16:02 ` Johannes Weiner
2015-01-23 16:59 ` Guenter Roeck
2015-01-23 17:36 ` Johannes Weiner
2015-01-23 17:38 ` Johannes Weiner
2015-01-24 2:02 ` Guenter Roeck
2015-01-27 17:24 ` Michal Hocko
2015-01-28 15:03 ` Christoph Lameter
2015-01-23 15:46 ` Guenter Roeck
2015-01-23 16:03 ` Johannes Weiner
2015-01-23 20:20 ` Christoph Lameter
2015-01-23 20:33 ` Guenter Roeck
2015-01-23 21:09 ` Christoph Lameter
2015-01-24 7:16 ` Johannes Weiner
2015-01-25 21:36 ` Valdis.Kletnieks
2015-01-26 13:37 ` Johannes Weiner
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