From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF9ECC43381 for ; Wed, 13 Mar 2019 04:47:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C01E521841 for ; Wed, 13 Mar 2019 04:47:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725859AbfCMEr3 (ORCPT ); Wed, 13 Mar 2019 00:47:29 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:50414 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725773AbfCMEr3 (ORCPT ); Wed, 13 Mar 2019 00:47:29 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2D4dSaN068542 for ; Wed, 13 Mar 2019 00:47:27 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0b-001b2d01.pphosted.com with ESMTP id 2r6t901xrs-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 13 Mar 2019 00:47:27 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 13 Mar 2019 04:47:22 -0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2D4lL8C28180590 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 13 Mar 2019 04:47:21 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 89197A4054; Wed, 13 Mar 2019 04:47:21 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 31817A405C; Wed, 13 Mar 2019 04:47:19 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.199.49.154]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 13 Mar 2019 04:47:18 +0000 (GMT) X-Mailer: emacs 26.1 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: dan.j.williams@intel.com, Ross Zwisler , Jan Kara , akpm@linux-foundation.org Cc: linux-nvdimm@lists.01.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, Alexander Viro Subject: Re: [PATCH v2] fs/dax: deposit pagetable even when installing zero page In-Reply-To: <20190309120721.21416-1-aneesh.kumar@linux.ibm.com> References: <20190309120721.21416-1-aneesh.kumar@linux.ibm.com> Date: Wed, 13 Mar 2019 10:17:17 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19031304-0028-0000-0000-0000035356B6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19031304-0029-0000-0000-00002411DD07 Message-Id: <8736nrnzxm.fsf@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-13_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903130033 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi Dan/Andrew/Jan, "Aneesh Kumar K.V" writes: > Architectures like ppc64 use the deposited page table to store hardware > page table slot information. Make sure we deposit a page table when > using zero page at the pmd level for hash. > > Without this we hit > > Unable to handle kernel paging request for data at address 0x00000000 > Faulting instruction address: 0xc000000000082a74 > Oops: Kernel access of bad area, sig: 11 [#1] > .... > > NIP [c000000000082a74] __hash_page_thp+0x224/0x5b0 > LR [c0000000000829a4] __hash_page_thp+0x154/0x5b0 > Call Trace: > hash_page_mm+0x43c/0x740 > do_hash_page+0x2c/0x3c > copy_from_iter_flushcache+0xa4/0x4a0 > pmem_copy_from_iter+0x2c/0x50 [nd_pmem] > dax_copy_from_iter+0x40/0x70 > dax_iomap_actor+0x134/0x360 > iomap_apply+0xfc/0x1b0 > dax_iomap_rw+0xac/0x130 > ext4_file_write_iter+0x254/0x460 [ext4] > __vfs_write+0x120/0x1e0 > vfs_write+0xd8/0x220 > SyS_write+0x6c/0x110 > system_call+0x3c/0x130 > > Fixes: b5beae5e224f ("powerpc/pseries: Add driver for PAPR SCM regions") > Reviewed-by: Jan Kara > Signed-off-by: Aneesh Kumar K.V Any suggestion on which tree this patch should got to? Also since this fix a kernel crash, we may want to get this to 5.1? > --- > Changes from v1: > * Add reviewed-by: > * Add Fixes: > > fs/dax.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/fs/dax.c b/fs/dax.c > index 6959837cc465..01bfb2ac34f9 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -33,6 +33,7 @@ > #include > #include > #include > +#include > #include "internal.h" > > #define CREATE_TRACE_POINTS > @@ -1410,7 +1411,9 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > { > struct address_space *mapping = vmf->vma->vm_file->f_mapping; > unsigned long pmd_addr = vmf->address & PMD_MASK; > + struct vm_area_struct *vma = vmf->vma; > struct inode *inode = mapping->host; > + pgtable_t pgtable = NULL; > struct page *zero_page; > spinlock_t *ptl; > pmd_t pmd_entry; > @@ -1425,12 +1428,22 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, > DAX_PMD | DAX_ZERO_PAGE, false); > > + if (arch_needs_pgtable_deposit()) { > + pgtable = pte_alloc_one(vma->vm_mm); > + if (!pgtable) > + return VM_FAULT_OOM; > + } > + > ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); > if (!pmd_none(*(vmf->pmd))) { > spin_unlock(ptl); > goto fallback; > } > > + if (pgtable) { > + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); > + mm_inc_nr_ptes(vma->vm_mm); > + } > pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); > pmd_entry = pmd_mkhuge(pmd_entry); > set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); > @@ -1439,6 +1452,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > return VM_FAULT_NOPAGE; > > fallback: > + if (pgtable) > + pte_free(vma->vm_mm, pgtable); > trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry); > return VM_FAULT_FALLBACK; > } > -- > 2.20.1 -aneesh