From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id B63236B0038 for ; Mon, 17 Oct 2016 15:29:51 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id gg9so211720722pac.6 for ; Mon, 17 Oct 2016 12:29:51 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id a13si26719341pag.258.2016.10.17.12.29.50 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 17 Oct 2016 12:29:50 -0700 (PDT) Date: Mon, 17 Oct 2016 13:29:49 -0600 From: Ross Zwisler Subject: Re: [PATCH 10/20] mm: Move handling of COW faults into DAX code Message-ID: <20161017192949.GA21002@linux.intel.com> References: <1474992504-20133-1-git-send-email-jack@suse.cz> <1474992504-20133-11-git-send-email-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1474992504-20133-11-git-send-email-jack@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, Dan Williams , Ross Zwisler , "Kirill A. Shutemov" On Tue, Sep 27, 2016 at 06:08:14PM +0200, Jan Kara wrote: > Move final handling of COW faults from generic code into DAX fault > handler. That way generic code doesn't have to be aware of peculiarities > of DAX locking so remove that knowledge. > > Signed-off-by: Jan Kara > --- > fs/dax.c | 22 ++++++++++++++++------ > include/linux/dax.h | 7 ------- > include/linux/mm.h | 9 +-------- > mm/memory.c | 14 ++++---------- > 4 files changed, 21 insertions(+), 31 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 0dc251ca77b8..b1c503930d1d 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -876,10 +876,15 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > goto unlock_entry; > if (!radix_tree_exceptional_entry(entry)) { > vmf->page = entry; > - return VM_FAULT_LOCKED; > + if (unlikely(PageHWPoison(entry))) { > + put_locked_mapping_entry(mapping, vmf->pgoff, > + entry); > + return VM_FAULT_HWPOISON; > + } > } > - vmf->entry = entry; > - return VM_FAULT_DAX_LOCKED; > + error = finish_fault(vmf); > + put_locked_mapping_entry(mapping, vmf->pgoff, entry); > + return error ? error : VM_FAULT_DONE_COW; > } > > if (!buffer_mapped(&bh)) { > @@ -1430,10 +1435,15 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > goto unlock_entry; > if (!radix_tree_exceptional_entry(entry)) { > vmf->page = entry; In __do_fault() we explicitly clear vmf->page in the case where PageHWPoison() is set. I think we can get the same behavior here by moving the call that sets vmf->page after the PageHWPoison() check. > - return VM_FAULT_LOCKED; > + if (unlikely(PageHWPoison(entry))) { > + put_locked_mapping_entry(mapping, vmf->pgoff, > + entry); > + return VM_FAULT_HWPOISON; > + } > } > - vmf->entry = entry; > - return VM_FAULT_DAX_LOCKED; I think we're missing a call to __SetPageUptodate(new_page); before finish_fault()? This call currently lives in do_cow_fault(), and is part of the path that we don't skip as part of the VM_FAULT_DAX_LOCKED logic. Both of these comments apply equally to the iomap_dax_fault() code. -- 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