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GET /api/patches/811799/?format=api
{ "id": 811799, "url": "http://patchwork.ozlabs.org/api/patches/811799/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/1504894024-2750-14-git-send-email-ldufour@linux.vnet.ibm.com/", "project": { "id": 2, "url": "http://patchwork.ozlabs.org/api/projects/2/?format=api", "name": "Linux PPC development", "link_name": "linuxppc-dev", "list_id": "linuxppc-dev.lists.ozlabs.org", "list_email": "linuxppc-dev@lists.ozlabs.org", "web_url": "https://github.com/linuxppc/wiki/wiki", "scm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git", "webscm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/", "list_archive_url_format": "https://lore.kernel.org/linuxppc-dev/{}/", "commit_url_format": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}" }, "msgid": "<1504894024-2750-14-git-send-email-ldufour@linux.vnet.ibm.com>", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/1504894024-2750-14-git-send-email-ldufour@linux.vnet.ibm.com/", "date": "2017-09-08T18:06:57", "name": "[v3,13/20] mm: Introduce __page_add_new_anon_rmap()", "commit_ref": null, "pull_url": null, "state": "not-applicable", "archived": false, "hash": "54d3585ae0b588c2b72e6b317306c75a2b40fe35", "submitter": { "id": 40248, "url": "http://patchwork.ozlabs.org/api/people/40248/?format=api", "name": "Laurent Dufour", "email": "ldufour@linux.vnet.ibm.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/1504894024-2750-14-git-send-email-ldufour@linux.vnet.ibm.com/mbox/", "series": [ { "id": 2269, "url": "http://patchwork.ozlabs.org/api/series/2269/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=2269", "date": "2017-09-08T18:06:44", "name": "Speculative page faults", "version": 3, "mbox": "http://patchwork.ozlabs.org/series/2269/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/811799/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/811799/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org>", "X-Original-To": [ "patchwork-incoming@ozlabs.org", "linuxppc-dev@lists.ozlabs.org" ], "Delivered-To": [ "patchwork-incoming@ozlabs.org", "linuxppc-dev@lists.ozlabs.org" ], "Received": [ "from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\t(using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xpmXG4xSFz9sBd\n\tfor <patchwork-incoming@ozlabs.org>;\n\tSat, 9 Sep 2017 04:47:26 +1000 (AEST)", "from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\tby lists.ozlabs.org (Postfix) with ESMTP id 3xpmXG3vkZzDrXS\n\tfor <patchwork-incoming@ozlabs.org>;\n\tSat, 9 Sep 2017 04:47:26 +1000 (AEST)", "from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com\n\t[148.163.156.1])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256\n\tbits)) (No client certificate requested)\n\tby lists.ozlabs.org (Postfix) with ESMTPS id 3xplfn2ZHWzDrYm\n\tfor <linuxppc-dev@lists.ozlabs.org>;\n\tSat, 9 Sep 2017 04:08:01 +1000 (AEST)", "from pps.filterd (m0098393.ppops.net [127.0.0.1])\n\tby mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id\n\tv88I5Jvp105168\n\tfor <linuxppc-dev@lists.ozlabs.org>; Fri, 8 Sep 2017 14:07:59 -0400", "from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110])\n\tby mx0a-001b2d01.pphosted.com with ESMTP id 2cuvgwkkwf-1\n\t(version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT)\n\tfor <linuxppc-dev@lists.ozlabs.org>; Fri, 08 Sep 2017 14:07:59 -0400", "from localhost\n\tby e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use\n\tOnly! Violators will be prosecuted\n\tfor <linuxppc-dev@lists.ozlabs.org> from <ldufour@linux.vnet.ibm.com>;\n\tFri, 8 Sep 2017 19:07:56 +0100", "from b06cxnps3075.portsmouth.uk.ibm.com (9.149.109.195)\n\tby e06smtp14.uk.ibm.com (192.168.101.144) with IBM ESMTP SMTP\n\tGateway: Authorized Use Only! Violators will be prosecuted; \n\tFri, 8 Sep 2017 19:07:50 +0100", "from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com\n\t[9.149.105.60])\n\tby b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with\n\tESMTP id v88I7nGP31260914; Fri, 8 Sep 2017 18:07:49 GMT", "from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1])\n\tby IMSVA (Postfix) with ESMTP id B592B42042;\n\tFri, 8 Sep 2017 19:04:16 +0100 (BST)", "from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1])\n\tby IMSVA (Postfix) with ESMTP id 9A0244203F;\n\tFri, 8 Sep 2017 19:04:13 +0100 (BST)", "from nimbus.lab.toulouse-stg.fr.ibm.com (unknown [9.145.31.125])\n\tby d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP;\n\tFri, 8 Sep 2017 19:04:13 +0100 (BST)" ], "Authentication-Results": "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com\n\t(client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com;\n\tenvelope-from=ldufour@linux.vnet.ibm.com; receiver=<UNKNOWN>)", "From": "Laurent Dufour <ldufour@linux.vnet.ibm.com>", "To": "paulmck@linux.vnet.ibm.com, peterz@infradead.org,\n\takpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, \n\tmhocko@kernel.org, dave@stgolabs.net, jack@suse.cz,\n\tMatthew Wilcox <willy@infradead.org>, benh@kernel.crashing.org,\n\tmpe@ellerman.id.au, paulus@samba.org,\n\tThomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, \n\thpa@zytor.com, Will Deacon <will.deacon@arm.com>,\n\tSergey Senozhatsky <sergey.senozhatsky@gmail.com>", "Subject": "[PATCH v3 13/20] mm: Introduce __page_add_new_anon_rmap()", "Date": "Fri, 8 Sep 2017 20:06:57 +0200", "X-Mailer": "git-send-email 2.7.4", "In-Reply-To": "<1504894024-2750-1-git-send-email-ldufour@linux.vnet.ibm.com>", "References": "<1504894024-2750-1-git-send-email-ldufour@linux.vnet.ibm.com>", "X-TM-AS-GCONF": "00", "x-cbid": "17090818-0016-0000-0000-000004EB9F57", "X-IBM-AV-DETECTION": "SAVI=unused REMOTE=unused XFE=unused", "x-cbparentid": "17090818-0017-0000-0000-00002825A70C", "Message-Id": "<1504894024-2750-14-git-send-email-ldufour@linux.vnet.ibm.com>", "X-Proofpoint-Virus-Version": "vendor=fsecure engine=2.50.10432:, ,\n\tdefinitions=2017-09-08_12:, , signatures=0", "X-Proofpoint-Spam-Details": "rule=outbound_notspam policy=outbound score=0\n\tspamscore=0 suspectscore=0\n\tmalwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam\n\tadjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000\n\tdefinitions=main-1709080270", "X-BeenThere": "linuxppc-dev@lists.ozlabs.org", "X-Mailman-Version": "2.1.23", "Precedence": "list", "List-Id": "Linux on PowerPC Developers Mail List\n\t<linuxppc-dev.lists.ozlabs.org>", "List-Unsubscribe": "<https://lists.ozlabs.org/options/linuxppc-dev>,\n\t<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>", "List-Archive": "<http://lists.ozlabs.org/pipermail/linuxppc-dev/>", "List-Post": "<mailto:linuxppc-dev@lists.ozlabs.org>", "List-Help": "<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>", "List-Subscribe": "<https://lists.ozlabs.org/listinfo/linuxppc-dev>,\n\t<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>", "Cc": "linuxppc-dev@lists.ozlabs.org, x86@kernel.org,\n\tlinux-kernel@vger.kernel.org, npiggin@gmail.com, linux-mm@kvack.org,\n\tTim Chen <tim.c.chen@linux.intel.com>, \n\tharen@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com", "Errors-To": "linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org", "Sender": "\"Linuxppc-dev\"\n\t<linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org>" }, "content": "When dealing with speculative page fault handler, we may race with VMA\nbeing split or merged. In this case the vma->vm_start and vm->vm_end\nfields may not match the address the page fault is occurring.\n\nThis can only happens when the VMA is split but in that case, the\nanon_vma pointer of the new VMA will be the same as the original one,\nbecause in __split_vma the new->anon_vma is set to src->anon_vma when\n*new = *vma.\n\nSo even if the VMA boundaries are not correct, the anon_vma pointer is\nstill valid.\n\nIf the VMA has been merged, then the VMA in which it has been merged\nmust have the same anon_vma pointer otherwise the merge can't be done.\n\nSo in all the case we know that the anon_vma is valid, since we have\nchecked before starting the speculative page fault that the anon_vma\npointer is valid for this VMA and since there is an anon_vma this\nmeans that at one time a page has been backed and that before the VMA\nis cleaned, the page table lock would have to be grab to clean the\nPTE, and the anon_vma field is checked once the PTE is locked.\n\nThis patch introduce a new __page_add_new_anon_rmap() service which\ndoesn't check for the VMA boundaries, and create a new inline one\nwhich do the check.\n\nWhen called from a page fault handler, if this is not a speculative one,\nthere is a guarantee that vm_start and vm_end match the faulting address,\nso this check is useless. In the context of the speculative page fault\nhandler, this check may be wrong but anon_vma is still valid as explained\nabove.\n\nSigned-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>\n---\n include/linux/rmap.h | 12 ++++++++++--\n mm/memory.c | 8 ++++----\n mm/rmap.c | 5 ++---\n 3 files changed, 16 insertions(+), 9 deletions(-)", "diff": "diff --git a/include/linux/rmap.h b/include/linux/rmap.h\nindex 733d3d8181e2..d91be69c1c60 100644\n--- a/include/linux/rmap.h\n+++ b/include/linux/rmap.h\n@@ -173,8 +173,16 @@ void page_add_anon_rmap(struct page *, struct vm_area_struct *,\n \t\tunsigned long, bool);\n void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,\n \t\t\t unsigned long, int);\n-void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,\n-\t\tunsigned long, bool);\n+void __page_add_new_anon_rmap(struct page *, struct vm_area_struct *,\n+\t\t\t unsigned long, bool);\n+static inline void page_add_new_anon_rmap(struct page *page,\n+\t\t\t\t\t struct vm_area_struct *vma,\n+\t\t\t\t\t unsigned long address, bool compound)\n+{\n+\tVM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);\n+\t__page_add_new_anon_rmap(page, vma, address, compound);\n+}\n+\n void page_add_file_rmap(struct page *, bool);\n void page_remove_rmap(struct page *, bool);\n \ndiff --git a/mm/memory.c b/mm/memory.c\nindex a5b5fe833ed3..479b47a8ed7c 100644\n--- a/mm/memory.c\n+++ b/mm/memory.c\n@@ -2508,7 +2508,7 @@ static int wp_page_copy(struct vm_fault *vmf)\n \t\t * thread doing COW.\n \t\t */\n \t\tptep_clear_flush_notify(vma, vmf->address, vmf->pte);\n-\t\tpage_add_new_anon_rmap(new_page, vma, vmf->address, false);\n+\t\t__page_add_new_anon_rmap(new_page, vma, vmf->address, false);\n \t\tmem_cgroup_commit_charge(new_page, memcg, false, false);\n \t\t__lru_cache_add_active_or_unevictable(new_page, vmf->vma_flags);\n \t\t/*\n@@ -2998,7 +2998,7 @@ int do_swap_page(struct vm_fault *vmf)\n \t\tmem_cgroup_commit_charge(page, memcg, true, false);\n \t\tactivate_page(page);\n \t} else { /* ksm created a completely new copy */\n-\t\tpage_add_new_anon_rmap(page, vma, vmf->address, false);\n+\t\t__page_add_new_anon_rmap(page, vma, vmf->address, false);\n \t\tmem_cgroup_commit_charge(page, memcg, false, false);\n \t\t__lru_cache_add_active_or_unevictable(page, vmf->vma_flags);\n \t}\n@@ -3144,7 +3144,7 @@ static int do_anonymous_page(struct vm_fault *vmf)\n \t}\n \n \tinc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);\n-\tpage_add_new_anon_rmap(page, vma, vmf->address, false);\n+\t__page_add_new_anon_rmap(page, vma, vmf->address, false);\n \tmem_cgroup_commit_charge(page, memcg, false, false);\n \t__lru_cache_add_active_or_unevictable(page, vmf->vma_flags);\n setpte:\n@@ -3396,7 +3396,7 @@ int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,\n \t/* copy-on-write page */\n \tif (write && !(vmf->vma_flags & VM_SHARED)) {\n \t\tinc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);\n-\t\tpage_add_new_anon_rmap(page, vma, vmf->address, false);\n+\t\t__page_add_new_anon_rmap(page, vma, vmf->address, false);\n \t\tmem_cgroup_commit_charge(page, memcg, false, false);\n \t\t__lru_cache_add_active_or_unevictable(page, vmf->vma_flags);\n \t} else {\ndiff --git a/mm/rmap.c b/mm/rmap.c\nindex b874c4761e84..5d657329191e 100644\n--- a/mm/rmap.c\n+++ b/mm/rmap.c\n@@ -1133,7 +1133,7 @@ void do_page_add_anon_rmap(struct page *page,\n }\n \n /**\n- * page_add_new_anon_rmap - add pte mapping to a new anonymous page\n+ * __page_add_new_anon_rmap - add pte mapping to a new anonymous page\n * @page:\tthe page to add the mapping to\n * @vma:\tthe vm area in which the mapping is added\n * @address:\tthe user virtual address mapped\n@@ -1143,12 +1143,11 @@ void do_page_add_anon_rmap(struct page *page,\n * This means the inc-and-test can be bypassed.\n * Page does not have to be locked.\n */\n-void page_add_new_anon_rmap(struct page *page,\n+void __page_add_new_anon_rmap(struct page *page,\n \tstruct vm_area_struct *vma, unsigned long address, bool compound)\n {\n \tint nr = compound ? hpage_nr_pages(page) : 1;\n \n-\tVM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);\n \t__SetPageSwapBacked(page);\n \tif (compound) {\n \t\tVM_BUG_ON_PAGE(!PageTransHuge(page), page);\n", "prefixes": [ "v3", "13/20" ] }