From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f49.google.com (mail-pb0-f49.google.com [209.85.160.49]) by kanga.kvack.org (Postfix) with ESMTP id 738CA6B00A7 for ; Wed, 13 Nov 2013 04:12:07 -0500 (EST) Received: by mail-pb0-f49.google.com with SMTP id um1so132580pbc.36 for ; Wed, 13 Nov 2013 01:12:07 -0800 (PST) Received: from psmtp.com ([74.125.245.180]) by mx.google.com with SMTP id hk1si22779969pbb.281.2013.11.13.01.12.04 for ; Wed, 13 Nov 2013 01:12:05 -0800 (PST) Message-ID: <528342E5.2030300@asianux.com> Date: Wed, 13 Nov 2013 17:14:13 +0800 From: Chen Gang MIME-Version: 1.0 Subject: Re: [PATCH] arch: um: kernel: skas: mmu: remove pmd_free() and pud_free() for failure processing in init_stub_pte() References: <528308E8.8040203@asianux.com> <52834138.7050005@nod.at> In-Reply-To: <52834138.7050005@nod.at> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Richard Weinberger Cc: Jeff Dike , Hugh Dickins , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, uml-devel , uml-user On 11/13/2013 05:07 PM, Richard Weinberger wrote: > Am 13.11.2013 06:06, schrieb Chen Gang: >> Unfortunately, p?d_alloc() and p?d_free() are not pair!! If p?d_alloc() >> succeed, they may be used, so in the next failure, we have to skip them >> to let exit_mmap() or do_munmap() to process it. >> >> According to "Documentation/vm/locking", 'mm->page_table_lock' is for >> using vma list, so not need it when its related vmas are detached or >> unmapped from using vma list. >> >> The related work flow: >> >> exit_mmap() -> >> unmap_vmas(); /* so not need mm->page_table_lock */ >> free_pgtables(); >> >> do_munmap()-> >> detach_vmas_to_be_unmapped(); /* so not need mm->page_table_lock */ >> unmap_region() -> >> free_pgtables(); >> >> free_pgtables() -> >> free_pgd_range() -> >> free_pud_range() -> >> free_pmd_range() -> >> free_pte_range() -> >> pmd_clear(); >> pte_free_tlb(); >> pud_clear(); >> pmd_free_tlb(); >> pgd_clear(); >> pud_free_tlb(); >> >> >> Signed-off-by: Chen Gang > > Sounds reasonable to me. > *But* there are patches you from out there that tried to fix similar issues and got reverted later. > Now I'm a bit nervous and want a ACK from mm folks to have this verified. > It's not that I don't trust you, but I really don't trust you. ;-) > OK, thanks. > Thanks, > //richard > > -- Chen Gang -- 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