From mboxrd@z Thu Jan 1 00:00:00 1970 In-reply-to: <1201078278.6341.47.camel@lappy> (message from Peter Zijlstra on Wed, 23 Jan 2008 09:51:18 +0100) Subject: Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in sys_msync() References: <12010440803930-git-send-email-salikhmetov@gmail.com> <1201044083504-git-send-email-salikhmetov@gmail.com> <1201078035.6341.45.camel@lappy> <1201078278.6341.47.camel@lappy> Message-Id: From: Miklos Szeredi Date: Wed, 23 Jan 2008 10:34:52 +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: a.p.zijlstra@chello.nl Cc: salikhmetov@gmail.com, linux-mm@kvack.org, jakob@unthought.net, linux-kernel@vger.kernel.org, valdis.kletnieks@vt.edu, riel@redhat.com, ksm@42.dk, staubach@redhat.com, jesper.juhl@gmail.com, torvalds@linux-foundation.org, akpm@linux-foundation.org, protasnb@gmail.com, miklos@szeredi.hu, r.e.wolff@bitwizard.nl, hidave.darkstar@gmail.com, hch@infradead.org List-ID: > On Wed, 2008-01-23 at 09:47 +0100, Peter Zijlstra wrote: > > On Wed, 2008-01-23 at 02:21 +0300, Anton Salikhmetov wrote: > > > > +static void vma_wrprotect(struct vm_area_struct *vma) > > > +{ > > > + unsigned long addr = vma->vm_start; > > > + pgd_t *pgd = pgd_offset(vma->vm_mm, addr); > > > + > > > + while (addr < vma->vm_end) { > > > + unsigned long next = pgd_addr_end(addr, vma->vm_end); > > > + > > > + if (!pgd_none_or_clear_bad(pgd)) > > > + vma_wrprotect_pgd_range(vma, pgd, addr, next); > > > + > > > + ++pgd; > > > + addr = next; > > > + } > > > +} > > > > I think you want to pass start, end here too, you might not need to > > sweep the whole vma. > > Also, it still doesn't make sense to me why we'd not need to walk the > rmap, it is all the same file after all. It's the same file, but not the same memory map. It basically depends on how you define msync: a) sync _file_ on region defined by this mmap/start/end-address b) sync _memory_region_ defined by start/end-address b) is a perfectly fine definition, and it's consistent with what this code does. The fact that POSIX probably implies a) (in a rather poorly defined way) doesn't make much difference, I think. Miklos -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org