Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752703AbaFEWrt (ORCPT ); Thu, 5 Jun 2014 18:47:49 -0400 Received: from g2t1383g.austin.hp.com ([15.217.136.92]:48820 "EHLO g2t1383g.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751651AbaFEWrr (ORCPT ); Thu, 5 Jun 2014 18:47:47 -0400 Message-ID: <1402007914.7963.8.camel@misato.fc.hp.com> Subject: Re: [PATCH v7 07/22] Replace the XIP page fault handler with the DAX page fault handler From: Toshi Kani To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, willy@linux.intel.com Date: Thu, 05 Jun 2014 16:38:34 -0600 In-Reply-To: <1400704507.18128.23.camel@misato.fc.hp.com> References: <1400704507.18128.23.camel@misato.fc.hp.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5 (3.8.5-2.fc19) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-05-21 at 14:35 -0600, Toshi Kani wrote: > On Sun, 2014-03-23 at 15:08 -0400, Matthew Wilcox wrote: > : > > +static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > > + get_block_t get_block) > > +{ > : > > + error = dax_get_pfn(inode, &bh, &pfn); > > + if (error > 0) > > + error = vm_insert_mixed(vma, vaddr, pfn); > > + mutex_unlock(&mapping->i_mmap_mutex); > > + > > + if (page) { > > + delete_from_page_cache(page); > > + unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, > > + PAGE_CACHE_SIZE, 0); > > + unlock_page(page); > > + page_cache_release(page); > > Hi Matthew, > > I am seeing a problem in this code path, where it deletes a page cache > page mapped to a hole. Sometimes, page->_mapcount is 0, not -1, which > leads __delete_from_page_cache(), called from delete_from_page_cache(), > to hit the following BUG_ON. > > BUG_ON(page_mapped(page)) > > I suppose such page has a shared mapping. Does this code need to take > care of replacing shared mappings in such case? Hi Matthew, The following change works in my environment. What do you think? Thanks, -Toshi --- fs/dax.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/dax.c b/fs/dax.c index 2d6b4bc..046c6d6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -26,6 +26,7 @@ #include #include #include +#include int dax_clear_blocks(struct inode *inode, sector_t block, long size) { @@ -385,6 +386,8 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, mutex_unlock(&mapping->i_mmap_mutex); if (page) { + if (page_mapped(page)) + try_to_unmap(page, TTU_UNMAP|TTU_IGNORE_ACCESS); delete_from_page_cache(page); unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, PAGE_CACHE_SIZE, 0); -- 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/