From: Ingo Molnar <mingo@kernel.org>
To: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Guan Xuetao <gxt@mprc.pku.edu.cn>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-s390@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net,
user-mode-linux-user@lists.sourceforge.net,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
cov@codeaurora.org, criu@openvz.org
Subject: Re: [PATCH v3 2/2] powerpc/mm: Tracking vDSO remap
Date: Wed, 25 Mar 2015 19:33:16 +0100 [thread overview]
Message-ID: <20150325183316.GA9090@gmail.com> (raw)
In-Reply-To: <b6ce07f8e1e0d654371aee70bd8eac310456d0df.1427289960.git.ldufour@linux.vnet.ibm.com>
* Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote:
> +static inline void arch_unmap(struct mm_struct *mm,
> + struct vm_area_struct *vma,
> + unsigned long start, unsigned long end)
> +{
> + if (start <= mm->context.vdso_base && mm->context.vdso_base < end)
> + mm->context.vdso_base = 0;
> +}
So AFAICS PowerPC can have multi-page vDSOs, right?
So what happens if I munmap() the middle or end of the vDSO? The above
condition only seems to cover unmaps that affect the first page. I
think 'affects any page' ought to be the right condition? (But I know
nothing about PowerPC so I might be wrong.)
> +#define __HAVE_ARCH_REMAP
> +static inline void arch_remap(struct mm_struct *mm,
> + unsigned long old_start, unsigned long old_end,
> + unsigned long new_start, unsigned long new_end)
> +{
> + /*
> + * mremap() doesn't allow moving multiple vmas so we can limit the
> + * check to old_start == vdso_base.
> + */
> + if (old_start == mm->context.vdso_base)
> + mm->context.vdso_base = new_start;
> +}
mremap() doesn't allow moving multiple vmas, but it allows the
movement of multi-page vmas and it also allows partial mremap()s,
where it will split up a vma.
In particular, what happens if an mremap() is done with
old_start == vdso_base, but a shorter end than the end of the vDSO?
(i.e. a partial mremap() with fewer pages than the vDSO size)
Thanks,
Ingo
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next prev parent reply other threads:[~2015-03-25 18:33 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-20 15:53 [PATCH 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-20 15:53 ` [PATCH 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-20 23:19 ` Richard Weinberger
2015-03-23 8:52 ` Ingo Molnar
2015-03-23 9:11 ` Laurent Dufour
2015-03-25 11:06 ` [PATCH v2 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-25 11:06 ` [PATCH v2 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-25 11:06 ` [PATCH v2 2/2] powerpc/mm: Tracking vDSO remap Laurent Dufour
2015-03-25 12:11 ` Ingo Molnar
2015-03-25 13:25 ` Laurent Dufour
2015-03-25 13:53 ` [PATCH v3 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-25 13:53 ` [PATCH v3 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-25 13:53 ` [PATCH v3 2/2] powerpc/mm: Tracking vDSO remap Laurent Dufour
2015-03-25 18:33 ` Ingo Molnar [this message]
2015-03-25 18:36 ` Ingo Molnar
2015-03-25 21:11 ` Benjamin Herrenschmidt
2015-03-26 9:43 ` Ingo Molnar
2015-03-26 10:37 ` Laurent Dufour
2015-03-26 14:17 ` Ingo Molnar
2015-03-26 14:32 ` Laurent Dufour
2015-03-26 17:37 ` [PATCH v4 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-26 17:37 ` [PATCH v4 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-26 17:37 ` [PATCH v4 2/2] powerpc/mm: Tracking vDSO remap Laurent Dufour
2015-03-26 18:55 ` Ingo Molnar
2015-03-27 11:02 ` Laurent Dufour
2015-03-26 23:23 ` [PATCH v3 " Benjamin Herrenschmidt
2015-03-25 21:09 ` Benjamin Herrenschmidt
2015-03-26 9:48 ` Ingo Molnar
2015-03-26 10:13 ` Laurent Dufour
2015-03-20 15:53 ` [PATCH " Laurent Dufour
2016-03-02 12:13 ` [PATCH 0/2] Tracking user space vDSO remaping Christopher Covington
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