From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id DA8CC21A134BB for ; Mon, 22 May 2017 07:41:00 -0700 (PDT) Date: Mon, 22 May 2017 16:40:57 +0200 From: Jan Kara Subject: Re: [PATCH 1/2] mm: avoid spurious 'bad pmd' warning messages Message-ID: <20170522144057.GD25118@quack2.suse.cz> References: <20170517171639.14501-1-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20170517171639.14501-1-ross.zwisler@linux.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Ross Zwisler Cc: Jan Kara , Eryu Guan , "Darrick J. Wong" , Matthew Wilcox , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Christoph Hellwig , linux-mm@kvack.org, Dave Hansen , Alexander Viro , linux-fsdevel@vger.kernel.org, Andrew Morton , "Kirill A . Shutemov" , linux-nvdimm@lists.01.org List-ID: On Wed 17-05-17 11:16:38, Ross Zwisler wrote: > When the pmd_devmap() checks were added by: > > commit 5c7fb56e5e3f ("mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd") > > to add better support for DAX huge pages, they were all added to the end of > if() statements after existing pmd_trans_huge() checks. So, things like: > > - if (pmd_trans_huge(*pmd)) > + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) > > When further checks were added after pmd_trans_unstable() checks by: > > commit 7267ec008b5c ("mm: postpone page table allocation until we have page > to map") > > they were also added at the end of the conditional: > > + if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd)) > > This ordering is fine for pmd_trans_huge(), but doesn't work for > pmd_trans_unstable(). This is because DAX huge pages trip the bad_pmd() > check inside of pmd_none_or_trans_huge_or_clear_bad() (called by > pmd_trans_unstable()), which prints out a warning and returns 1. So, we do > end up doing the right thing, but only after spamming dmesg with suspicious > looking messages: > > mm/pgtable-generic.c:39: bad pmd ffff8808daa49b88(84000001006000a5) > > Reorder these checks so that pmd_devmap() is checked first, avoiding the > error messages. > > Signed-off-by: Ross Zwisler > Fixes: commit 7267ec008b5c ("mm: postpone page table allocation until we have page to map") > Cc: stable@vger.kernel.org With the change requested by Dave this looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > mm/memory.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 6ff5d72..1ee269d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3061,7 +3061,7 @@ static int pte_alloc_one_map(struct vm_fault *vmf) > * through an atomic read in C, which is what pmd_trans_unstable() > * provides. > */ > - if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd)) > + if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd)) > return VM_FAULT_NOPAGE; > > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, > @@ -3690,7 +3690,7 @@ static int handle_pte_fault(struct vm_fault *vmf) > vmf->pte = NULL; > } else { > /* See comment in pte_alloc_one_map() */ > - if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd)) > + if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd)) > return 0; > /* > * A regular pmd is established and it can't morph into a huge > -- > 2.9.4 > -- Jan Kara SUSE Labs, CR _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934983AbdEVOlC (ORCPT ); Mon, 22 May 2017 10:41:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:41220 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934165AbdEVOlB (ORCPT ); Mon, 22 May 2017 10:41:01 -0400 Date: Mon, 22 May 2017 16:40:57 +0200 From: Jan Kara To: Ross Zwisler Cc: Andrew Morton , linux-kernel@vger.kernel.org, "Darrick J. Wong" , Alexander Viro , Christoph Hellwig , Dan Williams , Dave Hansen , Jan Kara , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@ml01.01.org, "Kirill A . Shutemov" , Pawel Lebioda , Dave Jiang , Xiong Zhou , Eryu Guan , stable@vger.kernel.org Subject: Re: [PATCH 1/2] mm: avoid spurious 'bad pmd' warning messages Message-ID: <20170522144057.GD25118@quack2.suse.cz> References: <20170517171639.14501-1-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170517171639.14501-1-ross.zwisler@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-05-17 11:16:38, Ross Zwisler wrote: > When the pmd_devmap() checks were added by: > > commit 5c7fb56e5e3f ("mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd") > > to add better support for DAX huge pages, they were all added to the end of > if() statements after existing pmd_trans_huge() checks. So, things like: > > - if (pmd_trans_huge(*pmd)) > + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) > > When further checks were added after pmd_trans_unstable() checks by: > > commit 7267ec008b5c ("mm: postpone page table allocation until we have page > to map") > > they were also added at the end of the conditional: > > + if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd)) > > This ordering is fine for pmd_trans_huge(), but doesn't work for > pmd_trans_unstable(). This is because DAX huge pages trip the bad_pmd() > check inside of pmd_none_or_trans_huge_or_clear_bad() (called by > pmd_trans_unstable()), which prints out a warning and returns 1. So, we do > end up doing the right thing, but only after spamming dmesg with suspicious > looking messages: > > mm/pgtable-generic.c:39: bad pmd ffff8808daa49b88(84000001006000a5) > > Reorder these checks so that pmd_devmap() is checked first, avoiding the > error messages. > > Signed-off-by: Ross Zwisler > Fixes: commit 7267ec008b5c ("mm: postpone page table allocation until we have page to map") > Cc: stable@vger.kernel.org With the change requested by Dave this looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > mm/memory.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 6ff5d72..1ee269d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3061,7 +3061,7 @@ static int pte_alloc_one_map(struct vm_fault *vmf) > * through an atomic read in C, which is what pmd_trans_unstable() > * provides. > */ > - if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd)) > + if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd)) > return VM_FAULT_NOPAGE; > > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, > @@ -3690,7 +3690,7 @@ static int handle_pte_fault(struct vm_fault *vmf) > vmf->pte = NULL; > } else { > /* See comment in pte_alloc_one_map() */ > - if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd)) > + if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd)) > return 0; > /* > * A regular pmd is established and it can't morph into a huge > -- > 2.9.4 > -- Jan Kara SUSE Labs, CR From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 22 May 2017 16:40:57 +0200 From: Jan Kara To: Ross Zwisler Cc: Andrew Morton , linux-kernel@vger.kernel.org, "Darrick J. Wong" , Alexander Viro , Christoph Hellwig , Dan Williams , Dave Hansen , Jan Kara , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, "Kirill A . Shutemov" , Pawel Lebioda , Dave Jiang , Xiong Zhou , Eryu Guan , stable@vger.kernel.org Subject: Re: [PATCH 1/2] mm: avoid spurious 'bad pmd' warning messages Message-ID: <20170522144057.GD25118@quack2.suse.cz> References: <20170517171639.14501-1-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170517171639.14501-1-ross.zwisler@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: On Wed 17-05-17 11:16:38, Ross Zwisler wrote: > When the pmd_devmap() checks were added by: > > commit 5c7fb56e5e3f ("mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd") > > to add better support for DAX huge pages, they were all added to the end of > if() statements after existing pmd_trans_huge() checks. So, things like: > > - if (pmd_trans_huge(*pmd)) > + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) > > When further checks were added after pmd_trans_unstable() checks by: > > commit 7267ec008b5c ("mm: postpone page table allocation until we have page > to map") > > they were also added at the end of the conditional: > > + if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd)) > > This ordering is fine for pmd_trans_huge(), but doesn't work for > pmd_trans_unstable(). This is because DAX huge pages trip the bad_pmd() > check inside of pmd_none_or_trans_huge_or_clear_bad() (called by > pmd_trans_unstable()), which prints out a warning and returns 1. So, we do > end up doing the right thing, but only after spamming dmesg with suspicious > looking messages: > > mm/pgtable-generic.c:39: bad pmd ffff8808daa49b88(84000001006000a5) > > Reorder these checks so that pmd_devmap() is checked first, avoiding the > error messages. > > Signed-off-by: Ross Zwisler > Fixes: commit 7267ec008b5c ("mm: postpone page table allocation until we have page to map") > Cc: stable@vger.kernel.org With the change requested by Dave this looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > mm/memory.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 6ff5d72..1ee269d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3061,7 +3061,7 @@ static int pte_alloc_one_map(struct vm_fault *vmf) > * through an atomic read in C, which is what pmd_trans_unstable() > * provides. > */ > - if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd)) > + if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd)) > return VM_FAULT_NOPAGE; > > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, > @@ -3690,7 +3690,7 @@ static int handle_pte_fault(struct vm_fault *vmf) > vmf->pte = NULL; > } else { > /* See comment in pte_alloc_one_map() */ > - if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd)) > + if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd)) > return 0; > /* > * A regular pmd is established and it can't morph into a huge > -- > 2.9.4 > -- Jan Kara SUSE Labs, CR -- 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