From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH v3 2/2] powerpc/mm: Tracking vDSO remap Date: Wed, 25 Mar 2015 19:36:47 +0100 Message-ID: <20150325183647.GA9331@gmail.com> References: <20150325121118.GA2542@gmail.com> <20150325183316.GA9090@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-wg0-f53.google.com ([74.125.82.53]:35296 "EHLO mail-wg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750819AbbCYSgw (ORCPT ); Wed, 25 Mar 2015 14:36:52 -0400 Content-Disposition: inline In-Reply-To: <20150325183316.GA9090@gmail.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Laurent Dufour Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Jeff Dike , Richard Weinberger , Guan Xuetao , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Arnd Bergmann , 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 * Ingo Molnar wrote: > > +#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. I.e. mremap() supports the shrinking (and growing) of vmas. In that case mremap() will unmap the end of the vma and will shrink the remaining vDSO vma. Doesn't that result in a non-working vDSO that should zero out vdso_base? Thanks, Ingo