Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

From: Helge Deller <deller@gmx.de>
To: Alexandre Ghiti <alex@ghiti.fr>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: "James E . J . Bottomley" <James.Bottomley@HansenPartnership.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	"David S . Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap
Date: Mon, 26 Aug 2019 22:37:37 +0000	[thread overview]
Message-ID: <9639ebd4-7dcb-0ea5-e0a6-adb8eaecd92a@gmx.de> (raw)
In-Reply-To: <abc7ed75-0f51-7f21-5a74-d389f968ee55@ghiti.fr>

On 26.08.19 09:34, Alexandre Ghiti wrote:
> On 6/20/19 7:03 AM, Alexandre Ghiti wrote:
>> This series fixes the fallback of the top-down mmap: in case of
>> failure, a bottom-up scheme can be tried as a last resort between
>> the top-down mmap base and the stack, hoping for a large unused stack
>> limit.
>>
>> Lots of architectures and even mm code start this fallback
>> at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
>> already failed on the whole address space: instead, simply use
>> mmap_base.
>>
>> Along the way, it allows to get rid of of mmap_legacy_base and
>> mmap_compat_legacy_base from mm_struct.
>>
>> Note that arm and mips already implement this behaviour.
>>
>> Alexandre Ghiti (8):
>>    s390: Start fallback of top-down mmap at mm->mmap_base
>>    sh: Start fallback of top-down mmap at mm->mmap_base
>>    sparc: Start fallback of top-down mmap at mm->mmap_base
>>    x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
>>    mm: Start fallback top-down mmap at mm->mmap_base
>>    parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
>>      bottom-up mmap
>>    x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
>>      mmap
>>    mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
>>      mm_struct
>>
>>   arch/parisc/kernel/sys_parisc.c  |  8 +++-----
>>   arch/s390/mm/mmap.c              |  2 +-
>>   arch/sh/mm/mmap.c                |  2 +-
>>   arch/sparc/kernel/sys_sparc_64.c |  2 +-
>>   arch/sparc/mm/hugetlbpage.c      |  2 +-
>>   arch/x86/include/asm/elf.h       |  2 +-
>>   arch/x86/kernel/sys_x86_64.c     |  4 ++--
>>   arch/x86/mm/hugetlbpage.c        |  7 ++++---
>>   arch/x86/mm/mmap.c               | 20 +++++++++-----------
>>   include/linux/mm_types.h         |  2 --
>>   mm/debug.c                       |  4 ++--
>>   mm/mmap.c                        |  2 +-
>>   12 files changed, 26 insertions(+), 31 deletions(-)
>>
>
> Any thoughts about that series ? As said before, this is just a preparatory patchset in order to
> merge x86 mmap top down code with the generic version.

I just tested your patch series successfully on the parisc
architeture. You may add:

Tested-by: Helge Deller <deller@gmx.de> # parisc

Thanks!
Helge