Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754502AbbHXNMK (ORCPT ); Mon, 24 Aug 2015 09:12:10 -0400 Received: from mail-ob0-f181.google.com ([209.85.214.181]:35766 "EHLO mail-ob0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754458AbbHXNMI (ORCPT ); Mon, 24 Aug 2015 09:12:08 -0400 MIME-Version: 1.0 In-Reply-To: <1440292628-22461-1-git-send-email-xerofoify@gmail.com> References: <1440292628-22461-1-git-send-email-xerofoify@gmail.com> Date: Mon, 24 Aug 2015 09:12:07 -0400 Message-ID: Subject: Re: [PATCH] nfs:Fix deadlock occurrence issue on error path in the function nfs_vm_page_mkwrite From: Trond Myklebust To: Nicholas Krause Cc: Anna Schumaker , Linux NFS Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1962 Lines: 51 On Sat, Aug 22, 2015 at 9:17 PM, Nicholas Krause wrote: > > This fixes a possible deadlock occurrence issue on the error path > in the function nfs_vm_page_mkwrite for checking if the calls to > the functions nfs_flus_incompatible and nfs_updatepage have failed > by incorrectly not jumping to the correct goto label out_unlock > for unlocking the locked structure page pointer thus causing a > deadlock due to not correctly unlocking the internal structure > page pointer used by the function nfs_vm_page_mkwrite that had > been previously locked with the function lock_page. Further more > we also remove the goto label out as no error paths in this function > now use this label and this label should be removed to avoid build > warnings related to having a undefined label. > > Signed-off-by: Nicholas Krause > --- > fs/nfs/file.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/nfs/file.c b/fs/nfs/file.c > index cc4fa1e..fe68ecc 100644 > --- a/fs/nfs/file.c > +++ b/fs/nfs/file.c > @@ -629,12 +629,11 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) > ret = VM_FAULT_LOCKED; > if (nfs_flush_incompatible(filp, page) == 0 && > nfs_updatepage(filp, page, 0, pagelen) == 0) > - goto out; > + goto out_unlock; > > ret = VM_FAULT_SIGBUS; > out_unlock: > unlock_page(page); > -out: > return ret; > } > > That's the success path that you are modifying, not the error path. Furthermore, the return value is still VM_FAULT_LOCKED, which means the caller expects the page to be returned in the locked state. So NACK.... Trond -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/