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GET /api/patches/811784/?format=api
HTTP 200 OK
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{
    "id": 811784,
    "url": "http://patchwork.ozlabs.org/api/patches/811784/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/1504894024-2750-5-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": "<1504894024-2750-5-git-send-email-ldufour@linux.vnet.ibm.com>",
    "list_archive_url": "https://lore.kernel.org/linuxppc-dev/1504894024-2750-5-git-send-email-ldufour@linux.vnet.ibm.com/",
    "date": "2017-09-08T18:06:48",
    "name": "[v3,04/20] mm: VMA sequence count",
    "commit_ref": null,
    "pull_url": null,
    "state": "not-applicable",
    "archived": false,
    "hash": "fe34f49b0d85c1fbb1337f38dd122d02841d822a",
    "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/1504894024-2750-5-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/811784/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/811784/checks/",
    "tags": {},
    "related": [],
    "headers": {
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        ],
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        "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 04/20] mm: VMA sequence count",
        "Date": "Fri,  8 Sep 2017 20:06:48 +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>",
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        "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",
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    },
    "content": "From: Peter Zijlstra <peterz@infradead.org>\n\nWrap the VMA modifications (vma_adjust/unmap_page_range) with sequence\ncounts such that we can easily test if a VMA is changed.\n\nThe unmap_page_range() one allows us to make assumptions about\npage-tables; when we find the seqcount hasn't changed we can assume\npage-tables are still valid.\n\nThe flip side is that we cannot distinguish between a vma_adjust() and\nthe unmap_page_range() -- where with the former we could have\nre-checked the vma bounds against the address.\n\nSigned-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>\n\n[Port to 4.12 kernel]\n[Fix lock dependency between mapping->i_mmap_rwsem and vma->vm_sequence]\nSigned-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>\n---\n include/linux/mm_types.h |  1 +\n mm/memory.c              |  2 ++\n mm/mmap.c                | 21 ++++++++++++++++++---\n 3 files changed, 21 insertions(+), 3 deletions(-)",
    "diff": "diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h\nindex 46f4ecf5479a..df9a530c8ca1 100644\n--- a/include/linux/mm_types.h\n+++ b/include/linux/mm_types.h\n@@ -344,6 +344,7 @@ struct vm_area_struct {\n \tstruct mempolicy *vm_policy;\t/* NUMA policy for the VMA */\n #endif\n \tstruct vm_userfaultfd_ctx vm_userfaultfd_ctx;\n+\tseqcount_t vm_sequence;\n } __randomize_layout;\n \n struct core_thread {\ndiff --git a/mm/memory.c b/mm/memory.c\nindex 530d887ca885..f250e7c92948 100644\n--- a/mm/memory.c\n+++ b/mm/memory.c\n@@ -1499,6 +1499,7 @@ void unmap_page_range(struct mmu_gather *tlb,\n \tunsigned long next;\n \n \tBUG_ON(addr >= end);\n+\twrite_seqcount_begin(&vma->vm_sequence);\n \ttlb_start_vma(tlb, vma);\n \tpgd = pgd_offset(vma->vm_mm, addr);\n \tdo {\n@@ -1508,6 +1509,7 @@ void unmap_page_range(struct mmu_gather *tlb,\n \t\tnext = zap_p4d_range(tlb, vma, pgd, addr, next, details);\n \t} while (pgd++, addr = next, addr != end);\n \ttlb_end_vma(tlb, vma);\n+\twrite_seqcount_end(&vma->vm_sequence);\n }\n \n \ndiff --git a/mm/mmap.c b/mm/mmap.c\nindex 680506faceae..0a0012c7e50c 100644\n--- a/mm/mmap.c\n+++ b/mm/mmap.c\n@@ -558,6 +558,8 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,\n \telse\n \t\tmm->highest_vm_end = vm_end_gap(vma);\n \n+\tseqcount_init(&vma->vm_sequence);\n+\n \t/*\n \t * vma->vm_prev wasn't known when we followed the rbtree to find the\n \t * correct insertion point for that vma. As a result, we could not\n@@ -799,6 +801,11 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,\n \t\t}\n \t}\n \n+\twrite_seqcount_begin(&vma->vm_sequence);\n+\tif (next && next != vma)\n+\t\twrite_seqcount_begin_nested(&next->vm_sequence,\n+\t\t\t\t\t    SINGLE_DEPTH_NESTING);\n+\n \tanon_vma = vma->anon_vma;\n \tif (!anon_vma && adjust_next)\n \t\tanon_vma = next->anon_vma;\n@@ -903,6 +910,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,\n \t\tmm->map_count--;\n \t\tmpol_put(vma_policy(next));\n \t\tkmem_cache_free(vm_area_cachep, next);\n+\t\twrite_seqcount_end(&next->vm_sequence);\n \t\t/*\n \t\t * In mprotect's case 6 (see comments on vma_merge),\n \t\t * we must remove another next too. It would clutter\n@@ -932,11 +940,14 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,\n \t\tif (remove_next == 2) {\n \t\t\tremove_next = 1;\n \t\t\tend = next->vm_end;\n+\t\t\twrite_seqcount_end(&vma->vm_sequence);\n \t\t\tgoto again;\n-\t\t}\n-\t\telse if (next)\n+\t\t} else if (next) {\n+\t\t\tif (next != vma)\n+\t\t\t\twrite_seqcount_begin_nested(&next->vm_sequence,\n+\t\t\t\t\t\t\t    SINGLE_DEPTH_NESTING);\n \t\t\tvma_gap_update(next);\n-\t\telse {\n+\t\t} else {\n \t\t\t/*\n \t\t\t * If remove_next == 2 we obviously can't\n \t\t\t * reach this path.\n@@ -962,6 +973,10 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,\n \tif (insert && file)\n \t\tuprobe_mmap(insert);\n \n+\tif (next && next != vma)\n+\t\twrite_seqcount_end(&next->vm_sequence);\n+\twrite_seqcount_end(&vma->vm_sequence);\n+\n \tvalidate_mm(mm);\n \n \treturn 0;\n",
    "prefixes": [
        "v3",
        "04/20"
    ]
}