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[115.124.30.130]) by mx.google.com with ESMTPS id g18-v6si1604782plo.341.2018.07.26.11.10.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Jul 2018 11:10:40 -0700 (PDT) Received-SPF: pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.130 as permitted sender) client-ip=115.124.30.130; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07487;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0T5ObfW8_1532628628; Received: from e19h19392.et15sqa.tbsite.net(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0T5ObfW8_1532628628) by smtp.aliyun-inc.com(127.0.0.1); Fri, 27 Jul 2018 02:10:35 +0800 From: Yang Shi To: mhocko@kernel.org, willy@infradead.org, ldufour@linux.vnet.ibm.com, kirill@shutemov.name, akpm@linux-foundation.org Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC v6 PATCH 1/2] mm: refactor do_munmap() to extract the common part Date: Fri, 27 Jul 2018 02:10:13 +0800 Message-Id: <1532628614-111702-2-git-send-email-yang.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1532628614-111702-1-git-send-email-yang.shi@linux.alibaba.com> References: <1532628614-111702-1-git-send-email-yang.shi@linux.alibaba.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Introduces three new helper functions: * munmap_addr_sanity() * munmap_lookup_vma() * munmap_mlock_vma() They will be used by do_munmap() and the new do_munmap with zapping large mapping early in the later patch. There is no functional change, just code refactor. Reviewed-by: Laurent Dufour Signed-off-by: Yang Shi --- mm/mmap.c | 120 ++++++++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 82 insertions(+), 38 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index d1eb87e..2504094 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2686,34 +2686,44 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, return __split_vma(mm, vma, addr, new_below); } -/* Munmap is split into 2 main parts -- this part which finds - * what needs doing, and the areas themselves, which do the - * work. This now handles partial unmappings. - * Jeremy Fitzhardinge - */ -int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, - struct list_head *uf) +static inline bool munmap_addr_sanity(unsigned long start, size_t len) { - unsigned long end; - struct vm_area_struct *vma, *prev, *last; - if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) - return -EINVAL; + return false; - len = PAGE_ALIGN(len); - if (len == 0) - return -EINVAL; + if (PAGE_ALIGN(len) == 0) + return false; + + return true; +} + +/* + * munmap_lookup_vma: find the first overlap vma and split overlap vmas. + * @mm: mm_struct + * @vma: the first overlapping vma + * @prev: vma's prev + * @start: start address + * @end: end address + * + * returns 1 if successful, 0 or errno otherwise + */ +static int munmap_lookup_vma(struct mm_struct *mm, struct vm_area_struct **vma, + struct vm_area_struct **prev, unsigned long start, + unsigned long end) +{ + struct vm_area_struct *tmp, *last; /* Find the first overlapping VMA */ - vma = find_vma(mm, start); - if (!vma) + tmp = find_vma(mm, start); + if (!tmp) return 0; - prev = vma->vm_prev; - /* we have start < vma->vm_end */ + + *prev = tmp->vm_prev; + + /* we have start < vma->vm_end */ /* if it doesn't overlap, we have nothing.. */ - end = start + len; - if (vma->vm_start >= end) + if (tmp->vm_start >= end) return 0; /* @@ -2723,7 +2733,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * unmapped vm_area_struct will remain in use: so lower split_vma * places tmp vma above, and higher split_vma places tmp vma below. */ - if (start > vma->vm_start) { + if (start > tmp->vm_start) { int error; /* @@ -2731,13 +2741,14 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * not exceed its limit; but let map_count go just above * its limit temporarily, to help free resources as expected. */ - if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) + if (end < tmp->vm_end && + mm->map_count > sysctl_max_map_count) return -ENOMEM; - error = __split_vma(mm, vma, start, 0); + error = __split_vma(mm, tmp, start, 0); if (error) return error; - prev = vma; + *prev = tmp; } /* Does it split the last one? */ @@ -2747,7 +2758,48 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, if (error) return error; } - vma = prev ? prev->vm_next : mm->mmap; + + *vma = *prev ? (*prev)->vm_next : mm->mmap; + + return 1; +} + +static inline void munmap_mlock_vma(struct vm_area_struct *vma, + unsigned long end) +{ + struct vm_area_struct *tmp = vma; + + while (tmp && tmp->vm_start < end) { + if (tmp->vm_flags & VM_LOCKED) { + vma->vm_mm->locked_vm -= vma_pages(tmp); + munlock_vma_pages_all(tmp); + } + tmp = tmp->vm_next; + } +} + +/* Munmap is split into 2 main parts -- this part which finds + * what needs doing, and the areas themselves, which do the + * work. This now handles partial unmappings. + * Jeremy Fitzhardinge + */ +int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, + struct list_head *uf) +{ + unsigned long end; + struct vm_area_struct *vma = NULL, *prev; + int ret = 0; + + if (!munmap_addr_sanity(start, len)) + return -EINVAL; + + len = PAGE_ALIGN(len); + + end = start + len; + + ret = munmap_lookup_vma(mm, &vma, &prev, start, end); + if (ret != 1) + return ret; if (unlikely(uf)) { /* @@ -2759,24 +2811,16 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * split, despite we could. This is unlikely enough * failure that it's not worth optimizing it for. */ - int error = userfaultfd_unmap_prep(vma, start, end, uf); - if (error) - return error; + ret = userfaultfd_unmap_prep(vma, start, end, uf); + if (ret) + return ret; } /* * unlock any mlock()ed ranges before detaching vmas */ - if (mm->locked_vm) { - struct vm_area_struct *tmp = vma; - while (tmp && tmp->vm_start < end) { - if (tmp->vm_flags & VM_LOCKED) { - mm->locked_vm -= vma_pages(tmp); - munlock_vma_pages_all(tmp); - } - tmp = tmp->vm_next; - } - } + if (mm->locked_vm) + munmap_mlock_vma(vma, end); /* * Remove the vma's, and unmap the actual pages